* GB785353 (A)

Description: GB785353 (A) ? 1957-10-30

Substituted pteridine derivatives

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The EPO does not accept any responsibility for the accuracy of data and information originating from other authorities than the EPO; in particular, the EPO does not guarantee that they are complete, up-to-date or fit for specific purposes.

PATENT SPECIFICATION 7 Date of Application and filing Complete Specification: Jan 29, 1954. No 18454/56. Application made in United States of America on Jan 30, 1953. (Divided out of No 785,351). 85353 p g Complete Specification Published: Oct 30, 1957. Index at acceptance:-Class 2 ( 3), C 2 B 3 (A 4: B: GI: G 4: G 5: G 8), C 2 B 37 (A 3: B 3: I: L). International Classification:-CO 7 d. COMPLETE SPECIFICATION Substituted Pteridine Derivatives We, MERCK & CO, INC, a corporation duly organised and existing under the laws of the State 'of New Jersey, United States of America, of Rahway, New Jersey, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, ito be particularly described in and by the following statement: - This invention relates to substituted pteridine derivatives In brief, this invention provides novel 2-amino-and 2-acylamino pteridines with substituents in the 4 and 6-positions and having ene of the general formulae V, VI and VII below The novel compounds may be obtained from the 2-halo-3,3 di(alkoxy or aralkoxy)-propionaldehydes which ate

claimed and may be prepared by the process described land claimed in the specification of our copendling Application No. 2842/54 (Serial No 785,351). In accordance with the present invention, the said substituted propionaldehyde (Formula II below) is condensed with a 2,4,5-triamino6-(hydroxy, alkoxy, aryloxy, or arallkoxy)pyrimidine (Formula III) to produce a 2amino-5,6-dihydropteridine of the Formula IV below, which is oxidized to remove the and 6-hydrogen atoms and produce a compound of Formula V below This compound can be acylated to produce a compound of general formula VI, which may then be hydrolysed to a 2-acylamino-4-hydroxy-6formyl pteridine (VII). The reactions referred to above and the formulae of the various compounds are shown in the following reaction scheme, in which X is a halogen, R is an alkoxy or aralkox Y radical, R' is a hydrox Y, alkoxy, aryloxy, or aralkoxy radical, and R 1 is an acyl radical (RJ 2 CHC HCHO + X H 26 (II) H 2 t R () 2 R' H 'Y'H CH(R)2 RX HN N (M) a' N H 2 k N N 2 (Ml) R/ N NO H \CH(R)2 N N<() OH N No/ CHO RIHN H N (En) The novel compounds of formula VII are useful as starting materials for the process described and claimed in the specification of our copending Application No 18455/56 (Serial No 785,354) for producing N-j p-l( 2acylamino-4 hydroxy-6 ptenidylmethylene) iminol benzoyl k glutamic acids, which can be readily converted in good yields to pteroylglutamic acid, otherwise called vitamin B(, by certain of the processes described and dlaimed in the specification of our copending Application No. 18456/56 (Serial No 785,355) The novel compounds of formula VI and VII are also readily converted to pteroylglutamic acid by certain of the processes described and claimed in the specification of our copending Application No 18456/56 (Serial No 785,355). The pteridine moiety, which is an osseni 4 m T Ptice 3 s 6 d l tial structural unit of pteroylglutamic acid, is produced by condensing a 2-halo-3,3-(dialkoxy or diaralkoxy)-propionaldehyde with a 2,4,5-triamino pyrimidine having in the 6 position a hydroxy, alkoxy, aryloxy, or aralkoxy radical to produce the corresponding 2amino-6-(dialkoxymeth'yl or diaralkoxymethyl)5,6-dihydropteridine Fortunately, the resulting pteridine moiety is practically all the 6methyl position isomer needed in the synthesis of biologically active compounds such as pteroylglutamic acid The condensation is preferably effected by intimately contacting the reactants in the presence of a solvent and a condensing agent The solvent can be water or an inert organic solvent or mixture of such solvents Illustrative of solvents which can be used are hydroxylated solvents such as alcohols and glycoes, particularly ethyl alcohol and ethylene glycol, and solvents such as acetone, benzene, land formamide Examples of condensing agents

which can be used are sodium acetate, disodium phosphate, silver carbonate, and sodium formate The reaction will, proceed at ordinary temperatures but the rate 'of reaction may be increased by using elevated temperatures such as 6 0165 ' C. The condensation resulting in formation of the pteridine nucleus proceeds satisfactorily regardless of the substituent in the 6 position of the 2,4,5-triamino pyrimidine used as reactant Thus, equally good results are obtained when the 6-substituent is hydroxy, an alkwxy radical such as ethoxy, propoxy or butoxy, an aryloxy radical such as phenoxy, or an aralkoxy radical such as benzyloxy However, the condensation is most easily accomplished when a 2-(bromo or chloro) 3,3-<dia 11 koxy or diaraikoxy)-propionaldehyde is used In specific embodiments of this condensation 2-amino4-benzyloxy 6 dietlhoxymethyl-5 6-dihydropteridine and 2-amino-4-hydroxy-6-diethoxymethyl-5,6-dihydrepteridine can be produced by condensing respectively 24,5-triamino-6benzyloxy pyrimidine and 2,4,5 triamino-6hydroxy pyrimidine with 2-bromo-3,3-diehoxy propionaldehyde in the presence of aqueous ethanol and sodium acetate After completion of the condensation the desired product can be recovered from the reaction mixture by conventional procedures or the reaction mixture can bh used directly in the preparation of the fully aromatic pteridine moiety. The fully aromatic 2-amino pteridinres having a hydroxy, alkoxy, aryloxy, ior aralkoxy radical in the 4 position and a dia Lkoxymethyi or diaralkoxyfnethyl radical tin the 6 position can be prepared by dehydrogenation of the correspondingly substituted 5,6-dihydropteridines. The dellydrogenation is readily accomplished by Intimately contacting the 5,6-dihydropteridine with a mild oxidizing agent Specific examples of suitable oxidizing agents are air, oxygen, iodine, and hydrogen peroxide with a ferrous salt In general, it is preferable to maintain a p H of about 8 to 9 to obtain best results In addition, the reaction is conveniently accomplished 'in a suitable inert solvent such as alcohols, glycols, acetone benzene, formamide, dioxane and water 70 The resulting pteridines can be isolated from the reaction mixture by conventional methods. According to specific applications of this dehydrogenation reaction, 2-amine-4-benzyloxy6-diethoxymnethyl pteridine and 2-amine-4 75 hydroxy-6-diethoxymethyl pteridine are produced by oxidizing respectively 2-amino-4benzyloxy-6-dietlio xymethyl 5,6-dihydropteridine and 2-amino-4-hydroxy-6-diethoxymethyl-5,6-dihydropteridine with hydrogen 80 peroxide and ferrous sulphate in a suitable solvent Examples of other representative pteridines wh Ich can be prepared in this manner

are 2-amino-4-butoxy-6-dibenzyl}xymethyl pteridine, 2-amino-4-ethoxy-6-dimeth 85 oxymethyl pteridine, and 2-amino-4-methoxy6-dipropoxymethyl pteridine. In the next step of the process 2-amino pteridines containing a hydroxy, alkoxy, aryloxy, or aralkoxy substituent in tlhe 4 pos:'non 90 and a dialkoxymetlhyl or diarylkcxymethyl substituent in the 6 position are ccnverted to the corresponding novel 2-acqlamino pteridines The acylation can be effected by intimately contacting the substituted 2-amino 95 pteridines with a suitable acylating agent such as an acyl halide or carbaxylic acid anhydride. Acetyl chloride, propionyl chloride, butyryl chloride, benzoyl bromide, acetic anhydride, propionic anhydride, butyric anhydride, and 100 benzoic anhydride are examples of suitable acylating agents The acylation is conducted an a liquid reaction medium which car be an inert organic solvent 'or an excess of the acylating agent In general, an added solvent is 105 not required since the acylating agents are usually liquids at normal or slghtly elevated temperatures Although the reaction proceeds at ordinary temperatures it is usually effected at higher temperatures such as the reflux 110 temperature to enhance the rate of reaction. The desired 2-acylamino pteridine can be isolated from the reaction mixture by conventional methods such as cooling and filtering to separate the crystalline product Accord 115 ing to this acylation procedure, 2-acylamino pteridines having the described substituents in the 4 and 6 positions can be readily prepared in which the acyl substituent is an alkyl, aryl, or aralkyl carbonyl radical Thus, some speci 120 fic 2-acylamino pteridines which can be produced according to this process are 2-propion:2 mido-4 benzyloxy 6 dimethoxyme-hyl preridine, 2-butyramido-4 hydroxy-6 dipropoxymethyl ptridine, 2-acetamido 4 125 phenoxy-6-diethoxymethyl pteridine, 2-acetamido-4-hydroxy-6-diethoxymethyl pteridine, 2-benzamido-4-hydroxy 6 diethoxymethyl pteridine, and 2-phenylacetarnido-4-hydroxy-6diethoxymethyl pteridine 130 785,353 cesses of the present invention. EXAMPLE 1. Production of 2-amino-4-benzylloxy-6-diethoxymethyl-5,6 dihydropiteridine and 2amino-4 benzyloxy 6 diethoxymethyl 70 pteridine. To a solution of 5 gin of 2-bromo-3,3-diethoxy-propionaldehyde in 70 nlt of ethanol was added a solution of 2,4,5-triamnino-6. benzyloxy-pyrimidine in 70 ml of ethanol 75 containing 2 gm of sodium acetate The solution was stirred at room temperature for 15 minutes and subsequently heated at 60-65 C for 90 minutes The reaction mixture was cooled to room temperature and added to 700 80 ml of water with

stirring to prepare for purification of the product. To the resulting slurry 2 5 N hydrochloric acid was added until the mixture became acidic Insoluble matter that formed was re 85 moved by filtration After cooling, the filtrate was added to an excess of 6 N ammonium hydroxide at a temperature of 5-10 C The amorphous precipitate was removed by filtration and dried The yield of 2-amino-4-benzyl 90 oxy-6-diethoxymlethyl 5,6-dihydropreridine was 3 5 gin. A sampie was purified further by dissolving it in ethyl acetate and adding n-liexane until the product precipitated 95 To an ethanolic solution of 2-amino-4benzyloxy-6-diethoxymethyl 5,6 dihydropteridine was added 50 mg of ferrous sulphate in 1 ml of water and then 2 3 gm of 30 % hydrogen peroxide in 10 ml of water was 100 added over a 30 minute period The mixture was concentrated under reduced pressure to a small volume and 2 5 N hydrochloric acid added to dissolve most of the oil The solution was separated from insoluble material by 105 decantation and added to an excess of cold 6 N ammonium hydroxide A precipitate restilted which was isolated and dried The yield of 2-amino-4-benzyloxy-6 diethoxymethyl pteridine was 4 gm and its ultraviolet 110 absorption spectrum in 0 1 N Na OH had maxima at 2560 A (E%= 369) and 3610 A (E% = 210); in 0 1 N H Cl it had a maximum at 3350 A (EB%= 364). By a paper-strip chromatography of the 115 acid obtained by permanganate oxidation of 2-amino-4-hydroxy-6-formyl ptedidine which was produced by acetal hydrolysis of 2-amino4-benzyloxy-6-diethoxymethyl pteridine, it was found that the product was all the de 120 sired 6-isomer. The solution of 2-amino-4-benzyloxy-6dietho-xymethyl-5,6-dihydropteiidine used in this example was prepared by reacting 4 6 gm of 2,4,5-trianino-6-b'enzyloxy pyrimidine 125 and 1 8 gm of sodium acetate in 63 mnl of ethanol with 45 gm lof 2-bromo-3,3-diethoxypropionaldehyde in 63 ml of ethanol. The acylated pteridines possess unique and valuable properties which distinguish them from the non-acylated pteridines For example, the non-acylated pteridines reported in the art are amorphous compounds which are nearly insoluble in ordinary solvents Therefore it was indeed surprising to discover that acylated pteridines, and derivatives of acylated pteridines could be readily produced in crystalline form Furthermore, the acylated pteridines were found to have van unexpectedly high solubility in water and many organic solvents The ability to produce crystalline compounds with high solubility by the introduction of an acyl group on the 2-amino was entirely unexpected since pteridines having such desirable properties were heretofore unkown This ceinbination of desirable properties

greatly enhances the usefulness of the 2-acylamino pteridines Thus, the production of crystalline pteridines is a great,aid in the purification of such coinpounds Because of their greater solubillity, the 2-acylamino pteridines can be used in reactions with smaller volumes of solvents than the non-acylated compounds, thereby allowing 25;a saving in material and permitting greater manipulative freedom. In the next step of the process, 2-acylanino pteridines substituted in the 4 position with a hydroxy, alkoxy, aryloxy, or aralkoxy radical and in the 6 position with a diailkoxymethyl or diaralkoxymethyl radical are hydrolysed with acid to the corresponding 2-acylamino-4hydroxy-6-formyl pteridine According to this 3 hydrolysis reaction the acetal radical in the 6 position is converted to a formny radical. Simultaneously pteridines which contain an alkoxy, aryloxy, or aralkoxy radical in the 4 position are hydrolysed to the corresponding 4-hydnoxy pteridines Either mineral or organic acids can be used for the hydrolysis. Examples of some suitable acids are hydrochloric acid, sulphuric acid, phosphoric acid, acetic acid, and formic acid The reaction is readily conducted in a solvent medium which can be an excess of the acid used or an added solvent such as water, or an inert organic solvent Normal or somewhat elevated temperatures may be used to promote the reaction. After the hydrolysis has been completed crystalline 2 acylamino-4-hydroxy-6-formyl ptetfdine is isolated by conventional methods. In specific applications of this reaction 2-acetamido-4-hydroxy-6-diethoxymethyl pteridine and 2-propionamido-4-bienzyloxy-6-methoxymethyl pteridine are hydrolysed with formic acid to 2-acetamidio-4-hydroxy-6-formyl pteridine and 2-propionamido-4-hydroxy-6-formyl pteridine Other similar compounds which can be prepared in this manner are 2-benzamido-4-hydroxy-6-formyl pteridine, 2-butyramido-4-hydroxy-6-forinyl pteridine land 2phenylac-etamido-4-hydroxy-6 formyl pteridine. The following examples illustrate the pro' 785,353 EXAMPLE 2. Production of 2-amino-4-hydroxy diethoxymethyl-5,6-dihydropteridme and 2-amino4-hydroxy-6-diethoxymethyl pteridine. g 5 0 gm of 2,4,5-c Lriamino-6-hydroxy pyrimidine sulphate was dissolved in 140 nil. of water containing 5 gin of barium chloride. The solution was heated to 60 ' C in a nitrogen atmosphere for 1 hour with stirring and subsequently filtered hot to remove the insoluble precipitate. To the resulting solution of 2,4,5-triamino6-hydroxy pyrimidine was

added 140 ml of ethanol and then 5 14 gm of 2-bromo-3,3diethoxy-propionaldehyde The reaction mixture was stirred under nitrogen at room temperature for 56 hours to yield a solution of 2-amino-4-hydroxy-6 diethoxymethyl 5,6dihydropteridine The solution was then adjusted to p H 8-9 and 50 mg of ferrous chloride and 2 6 gm of 30 G% hydrogen peroxide added at room temperature The solution was stirred for 5 hours, filtered, and the precipitate washed with water, alcohol, and ether to yield purified 2-amino-4-hydroxy-6diethoxymnethyl pteridine. A sample was purified by conversion to the sodium salt and reprecipitation of the original free base It had an ultraviolet absorption curve which exhibited, maxima in 0 1 N HIC at 3180 A (E%= 340) and in 0 1 N Na OH at 2550 A (E%= 941), 3620 A (E%'= 288). In a similar manner, 2-amino-4-hydroxy-6diethoxymethylpteridine was prepared by reacting 2-chiloro-3,3 diethoxy propionaldehyde with 2,4,5-triamino-6-hydroxy pyrimidine in ethanol and tin the presence of sodium acetate to produce 2-amino-4-hydroxy6 diethoxymethyl 5,6 dihydropteridine which was oxidized with hydrogen peroxide and ferrous sulphate to 2-amino-4-hydroxy-6diethoxymethyl pteridine. EXAMPLE 3. Production of 2-amino-4 hydroxy 6 dibenzyloxymethyl-5,6-dihydropteridine and 2 amino-4-hydroxy-6 dibenzyloxymethyl pteridine. After passing nitrogen through ia stirred solution of 8 2 gm of sodium acetate in a mixture of 200 ml of ethanol for 30 minutes, 4.7 gm of 2,4,5-triamino-6-hydroxy pyrimidine dihydrochloride and 7 0 gm of 2brono-3,3-dibenzyloxy-propionaldehyde were added to the solution The reaction mixture was stirred overnight at room temperature, forming 2-amino-4-hydroxy-6 dibenzyloxymethyl 5,6 dihydropteridine in solution. About 0 1 gin of ferrous sulphate was dissolved in 3 ml of waster and added to the reaction mixture together with 30 gin of 10 % hydrogen peroxide added dropwise The reaction mixture was filtered after standing overnight to give 2-amino-4-hydoxy-6-dibenzyloxymethyl pteridline which is readily purified by preparation of its sodium salt and reprecipitation of the free base. EXAMPLE 4. Production of 2-acetamido-4-hydroxy-6diethoxyinethyl pteridune. To a 3-necked flask equipped with stirrer and reflux condenser lwas acicted 4 2 gm of 2amino-4-hydroxy-6-dietlloxymethyl pteridine and 80 ml of acetic anhydride The mixture was refluxed with stirring for 1 5 hours To the solution was added 2 gm of activated carbon and refluxing was continued for 10 minutes The hot solution was filtered and cooled in the ice-box overnight The crystalline precipitate which formed was

filtered and washed with 10 ml of cold acetic anhydride and then with ether The precipitate was dried at 50 C under reduced pressure to yield white crystalline 2-acetamido-4-hydroxy-6diethoxymethyl pteridine A 1 gm sample of the product was recrystallized from 2 ml. of dioxane and melted at 198-200 ' C. The ultraviolet absorption curve exhibited maxima in 0 1 N HCI at 2330 as (E%,= 448), 2820 A (E'% = 380), and 3300 A (E% = 332), and in 0 1 N Na OH at 2560 As (E 1 %= 782) and 3500 A (E%,/= 227). EXAMPLE 5. Production of 2-propionamido-4-hydroxy-6diethoxymethyl pteridine. A slurry of 3 5 gm of 2-amino-4-hydroxy6-diethoxymethyl pter Idine in 70 gm of propionic anhydride was heated at 140 C for five hours during which time solution was effected To the reaction mixture was added 1.5 gin of charcoal and the mixture filtered. The filtrate was evaporated to about one-half volume and allowed to stand overnight in the cold The solid was collected by filtration, washed twice with ethyl ether and twice with petroleum ether After drying in air the lighttan crystals of 2-propionamido-4-hvdroxy-6diethoxymethyl pteridine weighed 2 95 gm. EXAMPLE 6. Production of 2-acetamido-4-hydroxy-6formyl pteridine. To a flask equipped with a stirrer was added 860 ml of 98 % formic acid and 58 gm of 2-acetamido-4 hydroxy-6 diethoxymethyl pteridine Complete solution was achieved in minutes Upon standing fcr 15 minutes at room temperature a precipitate appeared. The solution was allowed to stand under nitrogen in an ice-box overnight It was filtered and the precipitate was washed with cold formic acid and then anhydrous ether giving 2-acetamido-4-hydroxy-6-formyl pteridine. The ultraviolet absorption curve exhibited maxima in 0 1 N HCI at 2325 A (E;% = 488), shoulder 2900-3000 A (EO%= 443), and 3250 A (E% = 502) and in 0 1 N Na OH at 2550 (E%= 594), 2760 A (E%= 434) and 3650 A (E /0 = 394).

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* GB785354 (A)

Description: GB785354 (A) ? 1957-10-30

Substituted pteridine derivatives

Description of GB785354 (A) Translate this text into Tooltip

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The EPO does not accept any responsibility for the accuracy of data and information originating from other authorities than the EPO; in particular, the EPO does not guarantee that they are complete, up-to-date or fit for specific purposes.

PATENT SPECIFICATION 785,354 Date of Application and filing Complete Specification: Jan 29, 1954. No 18455/56. Application made in United States of America on Jan 30, 1953. (Divided out of No 785,351). Complete Specification Published: Oct 30, 1957. Index at acceptance: -Class 2 ( 3), C 2 B 37 (A 3: B 3: Cl: J: K: L: N). International Classification:-CO 7 d. COMPLETE SPECIFICATION Substituted Pteridine Derivatives We, MERCK & CO, I Nc, a corporation duly organised and existing under the laws of the State of New Jersey, United States of America, of Rahway, New Jersey, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - This invention relates to substituted pteridine derivatives which are useful in a novel and improved synthesis of pteroylglutamic acid (Vitamin B 0). In brief, this invention provides N p-l( 2acylamino-4-hydroxy 6 pteridylmethylene)iminolbenzoyl glutamic acids, which are -novel compounds having the general formula coon CH 0 h 2 in which R 1 ' is an acyl radical.

The invention also provides a method of obtaining the new compounds from the novel 2-acylamino-4-hydroxy 6 formyl-pteridines, which form part of the invention claimed in the specification of our copending application No 18454/56 (Serial No 785,353), and methods for converting the new compounds to 2-acylamino-pteroylglutamic acid, and hence to pteroyl-glutamic acid itself. In addition to being convertible to pteroylglutainic acid by way of 2-acylamino pteroylglutamic acid, the novel compounds are useful as starting materials for the process described and claimed in the specification of our copending Application No 18456/56 (Serial No 785,355) for preparing 2-acylamino-10-formylpteroylglutamic acid, which is itself readi 13 convertible to pteroylglutamic acid by processe: described and claimed in that specification. In accordance with the invention, the o H Schiff's base N p-l( 2-acylamino-4-hydroxy6-pteridylmethylene) iminol benzoyl glutamic acid is produced by bringing a 2-acylamino-4hydroxy-6-formyl pteridine into contact with L()-N-(p-amino-benzoyl) glutamic acid in the presence of a solvent In general, inert organic solvents can be used for the reaction medium Some examples of suitable solvents are the alcohols such as methanol, ethanol, propanol and dioxane The reaction can be carried out at room temperature or higher temperatures, e g, the reflux temperature of the solvent By cooling the mixture after the reaction has been completed the desired Schiff's base crystallizes from solution and is recovered by conventional methods According to this procedure N-t p l( 2-acylamino-4hydroxy-6 pteridylmethylene)iminolbenzoyl k glutamic acids can be prepared in which the acyl group is an alkyl carbonyl, aryl carbonyl or aralkyl carbonyl radical by selecting the corresponding 2-acylamino-4-hydroxy-6-fornyl pteridines for the reaction Representative of the broad class of Schiff's bases which can be prepared by this process are N-t p l( 2acetamido-4-hydroxy 6 pteridylmethylene) ininmolbenzoyl glutamic acid, N U p l( 2benzamido-4-hydroxy 6 pteridylmethylene) iminoibenzoyl tglutamic acid and N-t p-l 2butyrarnido-4-hydroxy 6 pteridylmethylene) iminolbenzoyl glutamic acid. In accordance with another embodiment of this invention a 2-acylamino pteroylglutamic acid can be produced by catalytic hydrogenation of the corresponding Schiff's base, N< p l( 2-acylamino 4 hydroxy-6-pteridylmethylene)iminolbenzoyl glutamic acid This reaction involves hydrogenation of the double bond in the imino group to form an amino group The usual hydrogenation catalysts may be used to effect the reaction although it is preferred to use Raney nickel The

hydrogenation is conducted in a suitable reaction medium such as water, dioxane, glacial acetic acid, quinoline, or a lower alcohol Superatmospheric pressures are generally used to aid the reaction. According to one embodiment of this process lPrice 3 s 6 d l : 2 ni 1 2-acetamido pteroylglutamic acid is produced by hydrogenating N-t p l( 2-acetamido-4hydroxy 6-pteridylmethylene)iminolbenzoyl t glutamic acid with Raney nickel in water. Other Schiff's bases such as N p-l( 2-phenylacetamido-4-hydroxy 6 pteridylmethylene)iminolbenzoyl glutamic acid, N p-l( 2-benzamido-4-hydroxy-6 -pteridylmethylene)iminol benzoyl kglutamic acid and N-t p-l( 2butyramido-4-hydroxy 6 pteridylmethylene)iminolbenzoyl kglutamic acid can also be hydrogenated by this procedure The resulting 2-acylamino pteroylglutamic acid may be readily hydrolysed by an inorganic or organic acid or base to pteroylglutamic acid. The invention is illustrated by the following examples: - EXAMPLE 1. Production of N p-l( 2-acetamido-4-hydroxy6 pteridylmethylene)iminolbenzoyl glutamic acid. To 660 ml of ethanol, contained in a litre flask equipped with stirrer and reflux condenser, was added 6 6 gin of L(-)N-(paminobenzoyl) glutamic acid The mixture was refluxed in a nitrogen atmosphere until a solution was complete ( 20 minutes) At this point 5 3 gin of 2-acetamido-4-hydroxy-6formyl pteridine was added Refluxing and stirring were continued for 1 hour during which the aldehyde dissolved The solution was filtered while hot and allowed to stand overnight at room temperature A yellow crystalline precipitate formed which was filtered and dried under reduced pressure at 1000 C to remove adsorbed solvent to produce N-< p l( 2-acetamido 4 hydroxy-6-pteridylmethylene)iminolbenzoyl glutamic acid. The ultraviolet absorption curve exhibited maxima in 0 1 N HCQ at a plateau 22302300 A (E 1 % = 411), 3350 A (E% = 186), and in 0 1 N Na OH at 2850 A (E% = 535), inflection 2700 A (E% = 466), and 3500 A (E% = 136). EXAMPLE 2. Production of 2-acetamido pteroylglutamic acid by catalytic reduction of N up l( 2acetamido-4-hydroxy-6-pteridylmethylene)iminolbenzoyl -glutamic acid. To 40 ml of water was added 0 96 gin of N. q p l( 2-acetamido 4 hydroxy-6-pteridylmethylene)iminolbenzoyl glutamic acid, 1 0 gm of sodium bicarbonate, and 1 0 gm of Raney nickel The mixture was hydrogenated at room temperature under 40 pounds per square inch pressure After one molar equivalent of hydrogen had been absorbed the catalyst was removed by filtration The filtrate

was acidified with 6 ml of glacial acetic acid. The mixture was allowed to stand in the cold overnight It was centrifuged and the solid 2-acetamido pteroylglutamic acid was washed with water, ethanol and ether.

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* GB785355 (A)

Description: GB785355 (A) ? 1957-10-30

Substituted pteridine derivatives

Description of GB785355 (A) Translate this text into Tooltip

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The EPO does not accept any responsibility for the accuracy of data and information originating from other authorities than the EPO; in particular, the EPO does not guarantee that they are complete, up-to-date or fit for specific purposes.

PATENT SPECIFICATION 78 5355 Date of Application and filing Complete Specification: Jan 29, 1954. No 18456156. Application made in United States of America on Jan 30, 1953. (Divided out of No 785,351). Complete Specification Published: Oct 30, 1957. Index at acceptance:-Class 2 ( 3), C 2 B 37 (A 2: A 3: Bl B 3: Cl: J: K: L). International Classification:-CO 7 d.

COMPLETE SPECIFICATION Substituted F Pteridine Derivatives We, MERCK & CO, INC, a corporation duly organised and existing under the laws of the State of New Jersey, United States of America, of Rahway, New Jersey, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - This invention relates to pteroylglutamic acid, commonly known as folic acid. Pteroylglutamic acid, or vitamin B, occurs naturally in yeast, liver, grasses and mushrooms This substance has been found to be therapeutically effective in the treatment of macrocytic anaemias, sprue, and other conditions of the circulatory system Although pteroylglutamic acid can be isolated from natural sources, it has been found that chemical synthesis of the vitamin is a more desirable method of production However, the syntheses of pteroylglutamic acid reported heretofore have not been entirely satisfactory due to low yields and inherent difficulties caused by the very low solubility of the intermediates used. The present invention provides 2-acylamino10-formyl-pteroylglutamic acids, which are novel compounds, and methods for preparing these compounds and converting them to pteroylglutamic acid. According to a first embodiment of the present invention, a 2-acylamino-10-formylpteroylglutamic acid (Formula X below) is obtained by adding formaldehyde to an N-t pl( 2-acylamino-4-hydroxy 6 pteridylmethylene)iminol benzoyl kglutamic acid (Formula IX below), one molecule of formaldehyde being added across the double bond Compounds of Formula IX are claimed and may be prepared by the method described and claimed in the specification of our copending Application No. 18455/56 (Serial No 785,354) According to a second embodiment of the invention, the 2acylamino-10-formyl-pteroylglutamic acid is then hydrolysed to pteroylglutamic acid (Formula XI below) This sequence of reactions is illustrated in the following scheme: lPrice 3 s 6 d l OH N coopi Rll H 1 \ 1 a C Ml/ = N I ON H-C" 2 H 7 CH 2 H a\ y H -O CH 2 R 8 NN N () coos O ON COOH OH CN 2-QCNN N () COON OH / N -COON N \ CH 2 NN-e CONH-CH H 2 N N N C AI COON PTEROYLGLUTAMIC ACID The 2-acylamino-10-formyl pteroylglutamic acid, in which the acyl substituent is an alkyl carbonyl, aryl carbonyl or aralkyl carbonyl radical is produced by bringing the Schiff's base N p-l( 2 acylamino 4 hydroxy-6pteridylmethylene) iminol benzoyl t glutamic acid into contact with formic acid The reaction is conveniently conducted in the presence of a solvent Examples of suitable solvents are the

hydroxylated solvents such as the lower alcohols, dioxane, ether, and the inert chlorinated hydrocarbons Alternatively, an excess of formic acid may be used for the reaction medium A small amount of acetic anhydride is ordinarily added in effecting the reaction since it serves to promote high yields of the desired 2-acylamino-10-formyl-pteroylglutamic acids Although the reaction proceeds at ordinary temperatures the rate of reaction is increased at elevated temperatures, e g at the reflux temperature of the solvent After the reaction has been completed the desired product can be isolated by cooling the reaction mixture and adding ether to precipitate the product In one embodiment of this method 2-acetamido-10-formyl pteroylglutamic acid is produced by reacting N-ip-l( 2-acetamido hydroxy 6 -pteridylmethylene)iminol benzo: glutamic acid in dioxane with formic ac Representative of other compounds which e be prepared according to this reaction by us: the appropriate Schiff's base are 2-benzamic 10-formyl pteroylglutamic acid, 2-butyramic 10-formyl pteroylglutamic acid, 2-propic amido-10-formyl pteroylglutamic acid and 0 phenylacetamido 10-formyl pteroylglutan acid. According to the next and last step, ptero: glutamic acid is produced by hydrolysing acylamino 10 formyl pteroylglutamic a( with an inorganic or organic acid base It preferred, however, to use the common i organic acids and bases such as sodh hydroxide, potassium hydroxide, hydrochlo. acid, sulphuric acid, and phosphoric acid T reaction is run by bringing the reactants it intimate contact in a suitable solvent such water or an inert organic solvent Elevat temperatures can be used, if desired, to pr mote the reaction After the hydrolysis h been completed the pteroylglutamic acid isolated from the reaction mixture by co ventional methods. Alternatively the 2-acylamino-10 form pteroylglutamic acid (X) can be produced I treating N ip l( 2-acylamlino 4 hydrox 6 pteridylmethylene)iminol benzoyl X-glutarn acid (IX) with a tri (lower alkyl) ammoniu formate, preferably triethyl ammoniu OH + " CHO m T c d R" V 11 OH 1 MO t y CH 1 HN 1 1 -4 formate (The term " lower alkyl " is used yl herein to refer to alkyl groups containing up to d be pcarbon atoms) The reaction is effected by -an bringing the reactants into intimate contact 2 ng at an elevated temperature, preferably at about lo 1500 G Although a solvent may be added it lo is generally preferred to use an excess of trin al 15 ylammonium formate as the reaction 2 medium After the reaction has gone to comnic pletion the product is recovered by conventional methods such as adding water to preyl cipitate the 2-acylamino-10-formyl pteroyl2 glutamic acid and filtering By following this -id procedure a large number of

2-acylamino-10is formyl pteroylglutamic acids can be prepared in in which the acyl group is an alkyl, aryl, or im aralkyl carbonyl radical Examples of cornric pounds which can be prepared in this fashion he by using the appropriate Schiff's base are 2Lto acetamido-10-formyl pteroylglutamic acid, 2as benzamido-10-formyl pteroylglutamic acid, 2ed butyramido-10-formyl pteroylglutamic acid, o and 2 phenylacetamido 10 formyl pteroylas glutamic acid. is Pursuant to an additional embodiment of n the invention it has been found that 2-acylamino-10-formyl pteroylglutamic acid (X) can yl be produced by bringing a 2-acylamino-4by hydroxy-6-formyl pteridine (VII) into intimate y contact with L(-)N (p aminobenzoyl) lic glutamic acid (VIII) in the presence of formic m acid This reaction can be illustrated as m follows: COH I Z 2 COOH I VIII p OOH COMM where R is an alkyl carbonyl, aryl carbonyl, or aralkyl carbonyl radical The reaction is effected in a suitable reaction medium which can be furnished by an added inert organic solvent or use of an excess of formic acid. Examples of solvents which can be used are dioxane, the lower alcohols such as ethanol and propanol, ether, and the inert chlorinated hydrocarbons An elevated temperature, such as the reflux temperature, is preferably used to aid dissolution of the reactants and complete the reaction in a short period of time A small amount of acetic anhydride may be present if desired In a specific embodiment of this process 2-acetamido-10-formyl pteroylglutamic acid is produced by condensing 2-acetamido-4hydroxy-6-formyl pteridine, L()N-(p-aminobenzoyl) glutamic acid and formic acid in dioxane In another specific application of this process, 2 acetamido 10 formyl pteroyl785,355 hols, water, ether, the inert chlorinated hydroh carbons, and formic acid, and a small amount a of acetic anhydride may be present if desired. In general, formic acid of approximately 98;% s purity has given the best results Elevated temperatures of 60-100 'C have been found c satisfactory for carrying out this process, c although higher and lower temperatures may 1 be used in special circumstances In a specific embodiment of this reaction 2-acetamido-10s formyl pteroylglutamic acid is prepared by condensing 2-acetamido 4 -hydroxy-6-formyl pteridine with L()N-(p-formamidobenzoyl) e glutamic acid in 98 % formic acid at about 1) 70 'C The L(-)N-(p-formamido benzoyl) glutamic acid may be readily prepared by heating L(-)N (p-aminobenzoyl) glutamic s acid with concentrated formic acid at a temyl perature of about 60-100 GC. i It has further been found that a 2-acylamiino-10 O-fcrnrmyl pteiaylglutamic acid (X) call be prepared by reacting a 2-acylamino pterie dine having in the 4 position a hydroxy, is allkoxy, aryloxy or

arallkoxy radical and in the o 6 position a dialloxymethyl or diaralkoxyd methyl radical (VI) with L()N-(p-aminobenzoyl) glutamic acid (VIII) and formic acid. This reaction may be illustrated as follows: co CK CH Ci 2 COCEI glutamic acid is formed by reacting 2-acet amido-4-hydroxy 6 formyl pteridine witl L(-)N-(p-aminobenzoyl) glutamic acid in ai excess of formic acid Illustrative of other 2 acylamino 10 formyl pteroylglutamic acid which can be produced in this way are 2 propionamido 10 formyl pteroylglutami, acid, 2-benzamido 10 -formyl pteroylglutami, acid, and 2-phenylacetamido 10 formy pteroylglutamic acid. According to a further embodiment of thi invention 2-acylamino 10 formyl pteroyl glutamic acid (X) is produced by reacting 2 acylamino 4 hydroxy-6-formyl pteridin (VII) with L()N-(p formamidobenzoyl glutamic acid, instead of L()N-(p-amino benzoyl) glutamic acid Examples of substi tuted pteridines which can be used in thi reaction are 2-acetamido 4 -hydroxy-6-form 3 pteridine, 2-phenylacetamido 4 hydroxy-6 formyl pteridine, 2-benzamido-4-hydroxy-6 formyl pteridine, and 2 butyramido 4 hydroxy-6-formyl pteridine Formation of th 2-acylamino-10-formyl pteroylglutamic acid i accomplished by bringing the reactants int intimate contact preferably in a suitable liqui reaction medium, e g, at the reflux tempera ture Some suitable solvents in which to con duct the reaction are dioxane, the lower alcc Ru / (R)2 RIC VI I L 1 Mtr CR O COC EN^<Avan can= 11 f o O % where R represents an alkoxy or aralkoxy radical, R' represents a hydroxy, alkoxy, aryloxy, or aralkoxy radical, and R is an acyl radical The reaction is achieved by bringing the reactants into intimate contact, preferably in a suitable solvent A small amount of acetic anhydride may be present if desired The solvent can be an excess of formic acid or an added inert organic solvent, examples of which are dioxane, the lower alcohols, ether, the inert chlorinated hydrocarbons, methyl Cellosolve and the saturated hydrocarbons such as hexane. (" Cellosolve " is a registered trade mark). Elevated temperatures, e g, the reflux temperature of the solvent, promote the reaction, the range 70-100 'C having been found quite satisfactory Such temperatures are however not essential After the reaction is completed, the product is isolated by ordinary procedures. In a specific application of this method 2acetamido-10-formyl pteroylglutamic acid is formed by reacting 2-acetamido-4-hydroxy-6diethoxymethyl pteridine with L( -)N-(paminobenzoyl) glutamic acid in 98 % formic acid at about 700 C Examples of other starting materials which can be reacted with L(-)N(p-aminobenzoyl) glutamic acid to produce the corresponding 2-acylamino-10-formyl pteroyl785,355 glutamic acid are

2-acetamido-4-benzyloxy-6dipropoxymethyl pteridine, 2-benzamido-4phenoxy-6-dibenzyloxymethyl pteridine, and 2-phenylacetamido 4 propoxy-6-dimethoxymethyl pteridine. Another embodiment of the invention provides a process analogous to the conversion of Formula (VI) to Formula (X) by using Formula (VIII) In this process, 10-formyl pteroylglutamic acid is produced by reacting a non-acylated 2-amino-pteridine having in the 4 position a hydroxy, alkoxy, aryloxy, or aralkoxy radical and in the 6 position a dialkoxymethyl or diara Lkoxymethyl radical 1 S (herein termed "Compound VW) with L( -)N(p-aminobenzoyl) glutamic acid (Compound VIII) in an excess of formic acid Some specific examples of the substituted 2-amino pteridines which can be used as starting materials are 2-amino-4-methoxy-6-diethoxymethyl pteridine, 2-amino 4 -phenoxy-6-dipropoxyinethyl pteridine, 2 amino-4-benzyloxy-6-dibenzoyloxy pteridine and 2-amino-4ethoxy-6-dimethoxymetlhyl pteridine The reaction is conducted in an excess of substantially pure formic acid at an elevated temperature to promote the reaction, a satisfactory temperature being about 70-800 C It is preferred to employ 98 % formic acid containing a small amount of acetic anhydride to obtain the highest yields In a specific application of this process 10-formyl pteroylglutamic acid is formed by reacting 2-amino-4-hydroxy6-diethoxymethyl pteridine with L(-)N-(paminobenzoyl) glutamic acid in an excess of formic acid at about 70 'C. In still another embodiment of the invention 2-acylamino-l O-formyl pteroylglutamic acid (X) can be prepared by reacting a 2acylamino 4 hydroxy 6-formyl-pteridine (VII) with L()N-(p-aminobenzoyl) glutamic acid (VIII) in the presence of a tri(lower alkyl) ammonium formate as defined above e g triethyl ammonium formate, at an elevated temperature This reaction can also be applied to the preparation of 10-formyl-pteroylglutamic acid by using a 2-amino-4-hydroxy-6-formylpteridine instead of Compound VII Examples of suitable starting materials for the first of these processes are 2-propionamido-4-hydroxy6-formyl pteridine, 2-benzamido-4-hydroxy-6formyl pteridine, 2-butyramido-4-hydroxy-6formyl pteridine, and 2-phenylacetamido-4hydroxy-6-formyl pteridine The desired 10formyl pteroylglu-tamic acid or its 2-acylamino derivatives are formed by bringing the reactants into intimate contact at an elevated temperature, for example about 150 C or above Temperatures substantially below 1500 C are not suitable to effect the reaction Atmospheric pressure or super-atmospheric pressures can be used The reaction may be carried out in solution in an excess of the trialkylammonium formate After the reaction is completed the reaction

mixture can be worked up according to conventional methods to obtain the product In a specific application of this reaction 10-formyl-pteroylglutamic acid is formed by reacting 2-acetamido-4hydroxy-6-formyl pteridine with L(-)N-(paminobenzoyl) glutamic acid in triethylammonium foimate at 150 C. Compounds VI and VII are claimed and may be prepared by the method described and claimed in the specification of our copending Application No 18454/56 (Serial No. 785,353) and Compound V is formed as intermediate in the preparation of Compound VI by that method. The following examples are presented to illustrate the processes in accordance with the invention. EXAMPLE 1 Production of 2-acetamido-10-formyl pteroylglutamic acid 85 A mixture of 100 ml of 98,% formic acid and 11 2 gm of acetic anhydride was prepared and allowed to stand overnight To 1 gm of N p l( 2-acetamido-4-hydroxy-6pteridylmethylene)iminolbenzoyl glutamic 90 acid was added 18 ml of the mixture of formic acid and acetic anhydride The resulting yellow solution was heated at 67 C for 1 hour during which time the solution became reddish The solution was cooled to room tem 95 perature and combined with 200 ml of anhydrous ether A reddish precipitate formed which was filtered and washed well with ether without exposing it to the atmosphere The resulting 2 acetamido-10-formyl-pteroylglu 100 tamic acid was dried under reduced pressure. EXAMPLE 2 Production of 2-acetamido-10-formyl pteroylglutamic acid by addition of formaldehyde to N p-l( 2-acetamido 4 hydroxy-6 105 pteridylmethylene)iminolbenzoyl > glutamic acid with triethylammonium formate A mixture of 0 96 gm of N p-l( 2-acetamido 4 hydroxy-6-pteridylmethylene)iminolbenzoyl tglutamic acid in 7 0 gm of 110 triethylammonium formate was heated at 1500 C for two hours After standing overnight at room temperature, the reaction mixture was diluted with 100 ml of water and cooled in the refrigerator for several hours The 2 115 acetamido-10-formyl pteroylglutamic acid was recovered by filtration and washed with water, acetone, and ether The product was assayed with L casei and found to possess folic acid activity 120 EXAMPLE 3 Production of 2-acetamido-10-formyl pteroylglutamic acid by condensing 2-acetamido-4hydroxy-6-formyl pteridine with L(-)-(paminobenzoyl) glutamic acid in dioxane in 125 the presence of formic acid To a boiling solution of 60 ml of dioxane was added 600 mg of L(-)N-(p-aminobenzoyl) glutamic acid and 400 mg of 2-acet785,355 2-acetamido-10-formyl pteroylglutamic acid was recovered by filtration

and washed with acetone and ether and dried It was found to have folic acid activity when assayed with L. casei. amido-4-hydroxy-6-formyl pteridine and the mixture refluxed until solution was complete. To the mixture was added a solution of 18 ml of formic acid and 3 ml of acetic anhydride The reaction mixture was refluxed for one hour, cooled, and 300 ml of ether added to precipitate the 2-acetamido-10formyl pteroylglutamic acid It was filtered, washed with ether and dried The product assayed 59 % folic acid against L casei. EXAMPLE 4 Production of 2-acetamido-10-formyl pteroylglutamic acid by condensing 2-acetamido-4hydroxy-6-formyl pteridine with L(-)N-(pformamido-benzoyl) glutamic acid To a solution of 400 mg of 2-acetamido10-formyl pteroylglutamic acid in 18 ml of 98 % formic acid containing a small amount of acetic anhydride was added 600 mg of L(-)N-(p-formamidobenzoyl) glutamic acid. The mixture was heated at 65-70 C for one hour and then cooled To this solution was added 200 ml of ether to precipitate 2acetamido 10 formyl pteroylglutamic acid. The solid was filtered, washed with ether and dried The product possessed activity to L. casei. The L(-)N-(p-formamidobenzoyl) glutamic acid used in this reaction was produced by heating 10 gm of L(-)N-(p-aminobenzoyl) glutamic acid in 25 ml of 85 % formic acid for one hour On cooling a white precipitate of L(-)N-(p-formamidobenzoyl) glutamic acid separated which was filtered, washed with ether and dried It melted at 190 C. EXAMPLE 5 Production of 2-acetamido-10-formyl-pteroylglutamic acid from 2-acetamido-4-hydroxy6-diethoxymethyl pteridine To 36 ml of 98 % formic acid at room temperature was added 1 gm of 2-acetamido4-hydroxy 6 diethoxymethyl pteridine and 1.80 gm of L(-)N-(p-aminobenzoyl) glutamic acid The mixture was heated to 700 C and solution effected After heating at 70-75 C. for 1 hour the reaction mixture was cooled and poured into 500 ml of ether The 2-acetamido-10-formyl-pteroylglutamic acid precipitated from solution and was filtered and washed with ether The product was dried under reduced pressure. EXAMPLE 6 Production of 2-acetamido-10-formyl pteroylglutamic acid by reacting 2-acetamido-4hydroxy-6-formyl pteridine with L(-)N-(paminobenzoyl) glutamic acid in triethylammonium formate. To a solution of 466 mg of 2-acetamido-4hydroxy-6-forinyl pteridine in

13 ml of triethyl ammonium formate was added 600 mg. of L(-)N-(p-aminobenzoyl) glutamic acid The mixture was heated to 1500 C for one hour and then concentrated under reduced pressure About 100 ml of acetone was added to the concentrate and a precipitate formed The EXAMPLE 7 Production of 10-formyl pteroylglutamic acid To 35 ml of formic acid was added 1 86 gm of 2 amino-4-benzyloxy-6-diethoxymethyl pteridine and 1 4 gm of L(-)N-(p 75 aminobenzoyl) glutamic acid The reactants dissolved readily to give a dark red solution which was heated at 670 C for one hour. The reaction mixture was cooled to 200 C. and poured into 400 ml of ether with stirring 80 The resulting precipitate was washed with formic acid, ether, water, and ether The product obtained contained 10-formyl pteroylglutamic acid and had an activity of 23 % when assayed with S faecalis 85 EXAMPLE 8 Production of 10-formyl pteroylglutamic acid by reacting 2 amino-4-hydroxy-6-formyl pteridine with L(-)N (p-aminobenzoyl) glutamic acid in triethyl ammonium form 90 ate A mixture of 1 0 gm of 2 amino-4hydroxy-6-formyl pteridine, 1 4 gm of L(-)N(p-aminobenzoyl) glutamic acid, and 15 gm. of triethyl ammonium formate was heated at 95 1500 C for one hour The reaction mixture was concentrated under reduced pressure below 1000 C and diluted with 100 ml of water The 10-formyl pteroylglutamic acid precipitated from the reaction mixture and 100 was recovered by filtration It was washed with water, acetone, and ether and dried in air The product has folic acid activity when assayed with L casei and S faecalis.

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* GB785356 (A)

Description: GB785356 (A) ? 1957-10-30

Improvements in or relating to flying spot scanning systems

Description of GB785356 (A)

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FR1092124 (A) US2903597 (A) FR1092124 (A) US2903597 (A) less Translate this text into Tooltip

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The EPO does not accept any responsibility for the accuracy of data and information originating from other authorities than the EPO; in particular, the EPO does not guarantee that they are complete, up-to-date or fit for specific purposes.

PATENT SPECIFICATION Iitventors: HUGH ALEXANDER DELL and MICHAEL ANTONY SNELLING Date of filing Complete Specification Dec IS, 1953. Application Date Jan 30, 1953. Complete Specification Published Oct 30, 1957. 785,356 No 2754/53. Index at Acceptance:-Class 40 ( 3), A 5 F( 1: 6), F( 2 E 1: 5 G). International Classification: -GO 8 c H 04 n. COMPLETE SPECIFICATION Improvements in or relating to 'Flying Spot Scanning Systems We, THE MULLARD RAD Io VALVE GOM The object of the present invention is to PANY LIMITED, of Spencer House, South provide an optical system producing the Place, Finsbury, London, E C 2, a British required multiple scanning light beams for Company, do hereby declare the invention, for scanning an object, for example a dust par 50 which we pray that a patent may be granted tide sample, having relatively few and to us, and the method by which it is to be simple optical elements of high optical performed, to be particularly described in and efficiency. by the following statement: According to the invention a flying spot The invention relates to flying spot scan scanning system of the kind first above 55 ning systems of the kind in which the object referred to comprises a flying spot light to be examined is scanned by at least two source tracing out a rectilinear raster, a first scanning beams scanning adjacent lines and lens or lens system for producing at a

first has particular reference to optical means for image plane a first focussed image of the flyderiving such scanning beams from a single ing spot light source, optical means for dis 60 flying spot light source placing the light entering a portion of such Such multiple spot scanning systems have lens or system so as to produce at said first already been proposed in particle counting image plane a second focussed image of said apparatus such as described in our copending flying spot having a separation from the first Applications No 15311/51 and No 17206/52 focussed image less than the excursion of the 65 (Serial Nos 741,471 and 747,718) which des images in the plane, and a second lens or lens cribe a "guard beam" technique for determin system of such a character and so disposed, ing when a particle is first (or last) seen by a in relation to said first lens or lens system that main scanning beam to avoid multiple count discrete illuminated areas corresponding to ing of a large particle overlapping two or the said portions of the first lens or lens sys 70 more scanning lines tem are produced at a second image plane. Various methods of deriving two scanning An object to be scanned, for example a dust beams from a single flying spot light source particle sample in the form of a transparency have also been described in these applications, may be positioned at the first image plane so for example when a flying spot scanner of the as to be scanned by both scanning beams and 75 cathode ray tube type is employed the elec a pick-up device for example a photo-electric tron beam may be " spot-wobbled " to pro cell may be associated with each discrete area vide effectively two scanning beams having the of illumination at or adjacent the second image desired scanning line separation In another plane so that each device provides an electrical example two scanning light beams having the signal which represents in amplitude and time 80 desired separation and having distinguishably the presence and distribution of the particles different optical properties, for example being traversed by the associated scanning beam. of different polarisation or of different colour, Such signals may be employed for counting have been proposed and/or sizing as described in our copending Both systems have certain disadvantages In Applications to which reference has been 85 the " spot-wobble " method difficulty may be made above. experienced in maintaining, to the desired In order that the invention may be more degree of accuracy, the separation of the two clearly understood it will now be described beams over the whole raster and in the case with reference to the drawings accompanying of polarised or coloured scanning beams the the Provisional Specification in which: 90 optical elements involved result in consider Figure 1 is a simplified diagram of an able loss of light optical system.

lPrice 3 s 6 d l Figure 2 is a diagram of an optical refracting system and Figure 3 is a schematic diagram of a flying spot scanning system according to the invent tion. Referring now to Figure 1 a light source S tracing out a scanning raster is represented as a flying spot scanner 1 of the cathode ray tube type but any other type of flying spot scanner may be employed A first lens or lens system L 1 projects a focussed image S, of the scanning spot at the image plane I Pl and a second lens or lens system L 2 which has an aperture sufficiently large to accept the most divergent rays from the image plane IP, produces an illuminated area A, A at the image plant IP 2 which is in fact an image of the Lens or lens system L,. Consideration of the paths of the light rays forming the image S shows that the illuminated area A,0 is formed by all the rays which have passed through the lower half of the lens L, whilst the area A O is formed by all the rays which have passed through the upper half of lens L,. Referring now to Figure 2 a refracting element R which may be an optical component such as a prism or a sheet of transparent material, for example, glass or synthetic material having the desired refractive index and shape, is positioned adjacent the lens or lens system L 1 in such a position as to refract the light rays from the source S which enter the lower half of the lens A duplicate image 52 of the image 51 is thereby formed at the image plane I Pl as indicated in the diagram and its distance from the image 51 will depend upon the character and disposition of the refracting element R It is to be noted that this element mernely shifts the light rays incident on the lower half of the lens L 1 as a whole so that the image 52 is in the position which would be occupied by an image cast by the lens L 1 without the refracting element R and with the source S shifted to the position S, Thus the duplicate image 52 is formed by all the rays which pass through the lower half of lens L 1 and the image 51 by all the rays which pass through the upper half of the lens L,. Figure 3 shows this refracting system included in the system shown in Figure 1 By arranging other suitable optical elements such as mirrors M 1 and M, at or near the image plane I Pi, the light rays forming the image S, can be directed into a pick-up device such as photo-cell PE 1 and all the rays forming the image 52 into a similar device PE 2. When such an optical system is used, for example in a particle counting apparatus for scanning a dust particle sample in the form of a microscope slide it may be desirable to employ a cathode ray tube of the projection type to provide the flying spot S and to employ such a lens system L 1 and refracting element R that the separation of the two scanning images S, and S is less than the excursion of each image

in the image plane IP, and the raster formed by the images is of the desired size to scan the sample or a desired portion 70 of it In an actual example this projected raster may be of square format with a side having a length of 100 microns The slide will of course be positioned accurately at the image plane I Pl so that it is scanned by the 75 sharply focussed images S, and 52 of the flying spot S The signals generated by the pickup devices may be used to obtain a count of the particles, to ensure that a large particle overlapping two or more lines of scan is only 80 counted once and, if desired, to determine the size distribution of the particles as described for example in our copending Applications Nos 15311/51 and 17206/52 (Serial Nos. 741,471 and 747,718) 85 The invention is not limited to the embodiment above described since changes may be made to suit particular circumstances as they arise in practice, for example in order to obtain optical symmetry two refracting ele 90 ments may be employed in the embodiment described each associated with one half of the lens system L, Further the arrangement may be extended to the production, in a like manner, of three or more scanning spots, from 95 a single flying spot source and by suitable construction of a refracting element it may be arranged to provide a scanning spot which is in focus in a different plane to that in which the other spot or spots is or are in focus so 100 enabling a sample to be additionally examined in depth.

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* GB785357 (A)

Description: GB785357 (A) ? 1957-10-30

An electronic regenerative repeater for telegraph signals in a start-stopcode

Description of GB785357 (A)

A high quality text as facsimile in your desired language may be available amongst the following family members:

BE518475 (A) CH310084 (A) DE980079 (C) FR1090395 (A) NL85212 (C) US2850567 (A) BE518475 (A) CH310084 (A) DE980079 (C) FR1090395 (A) NL85212 (C) US2850567 (A) less Translate this text into Tooltip

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PATENT SPECIFICATION 785,357 Date of Application and filing Complete Specification March 19, 1953. No 7685/53. Application made in Netherlands on March 24, 1952. Complete Specification Published Oct 30, 1957. The inventor of this invention in the sense of being the actual deviser thereof within the meaning of Section 16 of the Patents Actd 1949, is Antonie Snijders, a subject of the Queen of the Netherlands of 137, Driebergenstraat, The Hague, Holland. Index at acceptance:-Class 40 ( 3), H 16 (A 2: E 8). International Classification: -H 041. COMPLETE SPECIFICATION An Electronic Regenerative Repeater for Telegraph Signals in a Start-Stop Code We, STAATSBEDRIJF DER POSTERIJEN, TELEGRAFIE EN TELEFONIE, a Public Deparment of the Netherlands, of 12, Kortenaerkade, The Hague, the Netherlands do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed to the particularly described in and by the following statement: - The invention relates to an electronic regenerative repeater for telegraph signals in a startstop code. Regenerative repeaters of the type wherein a generator begins to operate in response to the start elemnt of an incoming signal some time after said start element is arnilied to the input of said

regenerative repeater, and wherein said generator is stopped by means of the restoration of a timing circuit into its normal condition said timing circuit being us in oneration by the generator, generator-impulses moreover fixing the moments at which the polarities of the incoming signal elements are apnlied consecutively to the output of said regenerative repeater by means of first sampling means are already kno-wn Such a regenerative repeater is described in British Patent Application Ne 29273/52 (Serial No. 765,953) However the regenerative repeater described therein includes an electronic distributor comprising a number of electrode systems at least equal to the number of elements to be distributed Further, the comnonent parts required are as follows; nine circuits allowing of two conditions, a generator with start-stop circuit and a seven-fold distributor. With the regenerative re Peater according to the uresent invention the number of compoent parts in the case of telegraph sirnals in the 5-unit code has been reduced to three circuits allowing of two conditions, a generator w X ith_ start-stop circuit and a timing circuit which, under the influence of an external interruption reverts to the initial stable condition after haying pased through unstable ones The latter lPrice 3 s 6 d l circuit can be obtained in a simple manner from the circuit allowing of two conditoins as used in the described embodiment of the invention Therefore there is no seven-unit distributor and the simpler construction is an advantage during manufacture. In accordance with the present invention, an electronic regenerative repeater for fele graph signals in a startstop code, wherein a generator begins to operate in response to the start element of an incoming signal some time after said start element is applied to the input of said regenerative repeater, and wherein said generator is stopped by means of the restoration of a timing circuit into its normal condition, said timing circuit being put in operation by the generator generator-impulses moreover fixing the moments at which the polarities o& the incoming signal elements are applied consecutively to the output of said regenerative repeater by means of first sampling means is characterized in that the output of said timing circuit is applied to second sampling means, also controlled bv generator pulses whereby a negative polarity appearing at said output in the restored condition of the timing circuit, after being sampled at the first operation of the generator, serves to set said timing circiut into the working condition, so that now a positive polarity at its output is applied to said second sampling means, said positive porality, being sampled at each subsequent impulse of the generator, and serving to set said timing circuit agnin into the normal condition.

The construction according to the invention is obtained by the polarities of the elements of the incoming signal controlling consecutively by means of the first sampling means the input of a trigger circuit serving as output circuit, the impulses required being supplied by the generator namely the two first being superd a': a moment half the theoretical duration of an element after the start, the operation of the generator being defined, by its impulses also 785,357 serving to put into operation a second sampling means which first scans a negative polarity, which results in a negative impulse being supplied to the control grid of that tube of a 2-tube timing circuit which is conductive in the rest condition, in which circuit this control grid is connected, via a capacity coupling tc the anode of the tube that is non-conductive in the rest condition and moreover across resistors to the positive pole of the voltage source owing to which impulse the timing circuit changes from the rest-condition into the working condition, in consequence of which the second sampling means scans positive polarity so that now positive impulses are supplied to the same above-mentioned control grid in behalf of the synchronization of the duration of the worlking condition of the circuit, which in its turn defines the duration of the operation of the generator It is remarked that it is a known idea to have the duration of the cyclus of a regenerative repeater defined bv a 2-tube circuit in which the control grid of the tube which is conductive in the rest condition is connected via a condenser to the anode of the tube which is non-conductive in the rest condition. As a matter of fact this idea has been applied in the British Patent No 709,901 The regenerative generator described in it is, however, an electro-mechanical one; therefore the said circuit contains relays. By using these relays a false start element can be ignored, in which case, however, the regenerative repeater does not revert immediately to the rest condition, which causes difficulties if a false or a good start element does occur again immediately The regenerative repeater according to the invention does revert to the rest condition immediately after receipt of a false start element. This regenerative repeater consists of the following parts: an input circuit (IS) which serves to provide the received signal with rectangular sides and to give the amplitude a specified value; a start-stop circuit (SSS) to start and stop the generator; 3 a 50 c/s generator circuit (G), which on its two outputs supplies impulses for the sampling of the received signal condition and of synchronization impulses; a timing circuit (DS) which serves as an auxiliary circuit for the starting and storning; 50 an impulse amplifier (IV) serving as an auxiliary circuit for the DS circuit; an output circuit (U) transmitting the regenerated signal.

The invention will be further described by means of the Figs 1 to 7 inclusive. Fig 1 shows a signal in the 5-unit startstop code. Fig 2 shows a so-called standard circuit (special flip-flop) which is usedl for the parts G 5 IS, DS, IV and U. Fig 3 represents grid current and voltages at various points of the standard circuit as a function of the input voltage. Fig 4 shows the start-stop circuit and the generator circuit 70 Fag 5 represents voltages at various points of the generator circuits as a function of time. Fig 6 represents the diagram of the regenerative repeater, in which the circuits that have already been given before are represented by 75 rectangles. Fig 7 consists of time diagrams for voltages at various points of the regenerative repeater. The figures have been designed for the case that signals in the 5-unit start-stop code are 80 used From the given description, however, circuits for signals in a start-stop code having another number of intelligence elements, can easily be derived The signals used for trpffic between teleprinters each consist of 7 ele 85 ments each element having a duration of 20 msec (Fig 1). The first element of the signal, the so-called start element, is always a marking element (W); this start element is followed by 5 so 90 called intellingence elements Each intelligence element can be either a marking (W) or a spacing element (R) After this follows the stop element which is alwavs a spacing element (R) 95 The distorted signal received by the regenerative repearter is retransmitted as an undistorted signal. It is started bv the start element of the incoming signal In connection with interfer 100 ences on the line the start element must have a duration of more than 10 msec to entail the starting of the regenerative repeater If the regnerative repeater has received a false start element (less than 10 msec) it must immedi 105 ately be able to ignore a new false start or to react correctly to a good start element 10 msec after the beginning of a good start element a brief "sampling" of the incoming signal condition takes place After that the 110 consecutive intelling ence elements are sampled every 20 msec and finally the stop element. At the same moment that an element is being sampled its re-transmission is commenced by the ounut circuit (U), the duration of which 115 elemnt re-transmission is 20 msec A description of the Darts indicated in Fin% 7 by rectangles now follows previous to the actual construction of the regenerative repeater For the parts IS IV and U the so-called standard 120 circuit (special two-state circiut forming

rart of the British Patent Apnlicat-on No 17359/ 52 (Serial No 780,001) is used For DS the standard circuit has been extended with some elements Therefore the operation of DS will 125 be discussed separately. This standard circuit (Fir 2) consists of a double triode (B,, B, a number of resistors and two neon indicator tubes (L,, L,) The tubes B, and B,, have a common cathode 130 785,357 resistor R 1,,, which is connected to the negative pole of battery V The anode resistors are formed by the parallel resistors R, and R, and R 4 and R 5 respectively, which are connected to the positive pole of battery V. To each anode is connected a potentiometer Rj RI, and, RJ/R 1, respectively whose other sides are connected to the negative pole of battery V The tappings 9 and 4 are the output terminals The resistors R, and R,8 are connected in series between the output terminals; the connecting point between these resistors is point 6 Furthermore there have been provided two high-ohmic potentiometers Rj/R,, and Rj/R,,, which are connected in parallel to the potentiometers RG/R,, and R/R,,, respectively The tapping point of potentiometer R/R 1 j is connected to the control oaid of tube Bib, and also via restistor R,7 to point 6. The tapping 5 to potentiometer R 7/R 14 is connected to point 6 via resistor R,, The control grid of tube Ba is connected to point 8 and via R,, to point 7 The anode of tube Bl, is connected to point 10, and the anode of tube Bib to point 3 To these points are moreover connected the indicator tubes L, and LX The indicator tubes are fed from the positive pole of battery V via resistor R, If the control grid of tube Ba is strongly negative with respect to the cathode, this tube does not carry current; via potentiometer Rj/RI, a positive voltage is applied to the control grid of tube B,b In this case tube Bib is conductive, the anode voltage of this tube is lower than that of tube Bl,, the neon tube L, glows, tube L, is extinguished The output terminal 9 has a higher voltage than the output terminal 4. The output terminal 6 has a voltage intermediate between the voltages of the output terminals 9 and 4 ( condition) If now the potential of the control grid of tube B,, increases, this tube will become conductive at a specified value as a result of which tube Bib becomes non-conductive The neon tube L, begins to glow and L extinguishes, the output terminals 9 and 4 change voltages (+ condition). The circuit is so dimensioned that with a small change of the input potential of point 7 the transition from the one condition into the other takes place substantially instantaneously. In either condition of the circuit point 6 has always the same voltage, because resistors R,2 and R,, are equal to each other If input terminal 7 has a voltage that is nearly equal to the voltage of

point 6 the condition of the circuit changes If the resistance value of the resistors R,, R,, R,, R,, Rf, R., R,,, R,, Rls and R,,, is 39 k Q, of the resistors R,, R,, R,3, R 14 and R,,= 1 Mid, if further R,= 820 ktl, R,,= 470 kfl, R,,= k Q, and R,7 = 270 k 52, the battery V having a voltage of 220 V with the -pole connected to earth, the output terminals 9 and 4 have a voltage of 80 V and 60 V respectively, with an input voltage which is lower than 70 V; terminal 6 has a voltage of 70 V If the input voltage is increased, the output voltages change to 60 V and 80 V respectively, with an input voltage of about 70 5 V If the input voltage is further increased the voltages occurring at the output terminals remain practically the same If the input voltage is decreased the circuit will revert to the original condition with an input voltage of about 69 5 V In Fig 3 the grid current of tube Ba and voltages at various points of the circuit are drawn as functions of the input voltage If the output terminals 9 and 4 are loaded, their voltages will change and the voltage at point 6 changes also As a result of the coupling of the control grid of tube Bib via resistor R,, to point 6 there will be in the case of loaded output terminals, change of the input voltage whereby the circuit changes its condition, for this input voltage is always nearly the average of the voltages at the output terminals 9 and 4. If several circuits must co-operate, the points 6 are connected, so that the voltage levels become equal as much as possible. The output terminal 5, which is of a highohmic nature, may be connected to the input terminal 7, so that the condition of the circuit remains unchanged, after the controlling input voltage has been removed The standard circuit has now become a trigger circuit arranged to have two stable states so as to be able to retain a condition in which it is set. THE GENERATOR AND THE START-STOP CIRCUIT 100 The generator circuit is a normal multivibrator circuit working at a frequency of c/s. The start-stop circuit forming part of the British Patent Application No 29273/52 105 (Serial No 765,953) is used to start the generator at the beginning of a signal and to stop it at the end of a signal Fig 4 shows the start-stop circuit and the generator circuit. Each circuit comprises a double triode The 110 values of the resistors are in Fig 4: R,"R 2,= 1 2 M 9, R,,= 820 k Q and R 2 = 27 kn, and in Fig 5: RL,=R,2,=R,,=R,,= 10 kn, R,= 680 k Q, R 7 =R,= 1 M&}, R,=R,,= 56 ki, R,,=%R,= 270 ki, R,,=R,4 = 39 k Q 115 R,,,=R,= 560 kn, and R,,= 47 k 12 C, and C, (Fig 5) are of about 20000 p F The voltage at the cathode of the double triode of the start-stop circuit is about 70 V If the control grid of tube BW, has a voltage lower than 120 V, this tube does not carry current; as a result of this tube B b does carry current In the anode lead of this latter tube has been inserted

resistor R, of the generator circuit. In consequence the control grid of the tube 125 B,;, of the generator is given the same negative potential with respect to the cathode as it also has if the tube B,, is non-conductive during the operation of the multivibrator. The control grid of the tube B,,, of the generator is connected to a positive voltage via resistors R 3, and R 29 This tube is conductive; the neon tube Lf glows The condensers Cl and C are so charged as to have equal voltages If the voltage at the control grid of tube Bo, of the start-stop circuit is increased, this tube will become conductive and tube Bb non-conductive wit habout 70 V grid voltage on B Wa Condenser C, will now begin to discharge itself across resistor Ro,; the control grid voltage of tube B-, will increase After msec tube B,, of the generator circuit will become conductive; the voltage dro D in the anode lead is transferred to the control grid of tube Bb via the condenser C, as a result of which tube Bb becomes non-conductive Condenser C, is now quickly recharged to the original high value, across the anode resistors R,, and R,, Owing to the discharge of condenser C 2 across resistor Roa the control arid of tube Bl,, will now reach again the potential of the cathode after 10 msec, which causes this tube to become conductive again and tube B b to become non-conductive, etc To stop the generator, tube B, of the start-stop circuit must be put again in the non-conductive condition by reducing the control grid voltage of this tube to below 70 V It is to be noted that, if tube B 2 _ of the start-stop circuit becomes conductive for a shorter time than msec, the generator tubes do not change their conductivity conditions If desired however, this period may be shortened or lengthened in two ways, viz:17 by choosing the various elements of the circuit in such a manner that if tube B,, carries current the control grid of tube B, will have either a higher or a lower potential than this grid has when tube BW, is in the non-conductive condition during the operation of the multivibrator, or 2 by choosing the values of Cl and C, unequal (but so that the multivibrator continues to work at a frequency of 50 c/s). Fig 5 shows in its upper part the potentials of points 3 and 8 of the circuit according to Fig 4, in its lower part the potentials of points 10 and 5 of the same circuit, all four as a function of the time and for the duration of a complete signal The difference between the potentials of points 3 and 8 represents the voltage in condenser CQ, that between points and 5 the voltage in condenser Cl, that 10 and 5 the voltage in condenser CQ The cathode potential of the generator is indicated by a dash-dotted line Moreover the dash-lines in Fig 5 show what happens in case of a false start. The frequency of the generator can be adjusted by means of resistor

R,,. The neon indicator tubes L, and L, always indicate which tube is conductive. THE REGENERATIVE REPEATER. In the diagram shown in Fig 6 the parts described in the preceding sections are, for the sake of simplicity, represented as rectangles; the numbers in these rectangles correspond with those used in the preceding figures In the irst place it must be observed that the 70 points 6 of the circuits are connected to earth. As a result of this the input level whereby the circuits change their condition is nearly equal to earth potential and the output voltages now have a value of + 10 V and -10 V 75 with respect to earth The positive pole of the 220 V battery is connected to all points marked with a + sign, and the negative pole to the terminals marked with the sign. The + terminals now have a voltage of + 150 80 V with respect to earth, and the terminals have a voltage of -70 V with respect to earth The circuits IS, IV and U are standard circuits according to Fig. 2 The circuit SSS is according to stage 85 B,, Bb in Fig 4 The circuit G is according to stage B 3;, B-, in Fig 4 The timing circuit DS is a standard circuit according to Fig. 2, the control grid of the left tube which in the rest condition is conductive being con 90 nected, however, via a condenser C to the anode of the tube which in the rest condition is non-conductive, this control grid being connected to the positive pole of the battery via resistor R_ and potentiometer R,; Owing to 95 this Fig 3 does not apply to this circuit Its function will be further explained in what follows The signal to be regenerated arrives at the input terminal 1 Point a, which is connected via rectifying cells G, and G 100 respectively, to the output terminal 9 of IS and to point r (at the output terminal 4 of DS), assumes the most negative voltage of the two points and so is negative in the idle condition (Here and in what follows use is made 105 of the operation of a relay cell according to the British Patent Application No 17359/52) (Serial No 780,001) By a relay cell is meant a common point (e g point a) connected to which is a group of rectifying cells (e g G,, 110 G-, G) conductive in the same direction. Terminal 8 of the SSS circuit, which is connected via rectifying cells G, and G, to point a and to terminal 9 of circuit DS respectively, assumes the most positive voltage of the two 115 points and therefore is also negative (In the idle condition the left-hand tube of DS is ductive, for its control grid is positive via the resistors R, and R,) So tube B_, of the start-stop circuit SSS is non-conductive and 120 generator G does not operate.

If now a signal arrives, the input terminal 1 becomes negative as a result of the start element; point a becomes Positive and consequently also terminal 8 of SSS After 10 msec 125 the generator changes its conductivity condition and it gives a positive impulse via condenser C, and a negative via C; These impulses are led to 2 sampling devices, each consisting of 6 rectifying cells, viz G,, to G 2, 130 785,357 785,357 inclusive, and G, to G 1, inclusive The operation of these sampling devices is the same as in the British Patent Application No 29273/ 52 (Serial No 765,953) and can be explained as follows for e g G 1, to G,, inclusive. The Potentiometers R 45/R 46 and R 48/ R 47 are chosen in such a manner that point c has a voltage of 10 V negative with respect to earth, and point d a voltage of 10 V positive with respect to earth The voltage of point e is equal to the most negative voltage of points c and g Irrespective of the voltage of point , point e therefore therefore has a negative voltage, so long as c remains negative Point f has a voltage equal to the most positive voltage of points d and g, and because d is positive, point f has a positive voltage with respect to earth This voltage, too, is independent of the voltage of point i, so long as d remains positive The rectifying cells G,, and G 1, are non-conductive; the connecting point h can assume any potential between + 10 V and -10 V In the idle condition condition this will be a positive potential, as DS and IV are then in the + condition 10 msec after the beginning of the start element, however, point c receives a positive and point d a negative impulse Point i was negative (for output terminal 9 of DS is negative) and so point e remains negative, point f becomes negative. So via the rectifying cell GIG the impulse amplifier IV is now put in the condition. At its output terminal 3 and via condenser C, this amplifier will immediately give a negative impulse of a higher energy than the one it received itself, to condenser CQ This results in the left-hand tube of DS becoming less conductive and the right-hand one becoming conductive, this resulting again in the control grid of the left-hand tube becoming more negative and the left-hand tube non-conductive The negative charge on C, will flow away via R 4, and R 4,, after which the tubes are restored to the old conductive or nonductive condition The value of R,4, is so chosen that the time required for the flowing away is about 120 msec During this time DS is in the condition and consequently, as the output terminal 5 of DS is connected with the input terminal 7 of IV, so is IV Output terminal 9 of DS has + polarity during this time, so via rectifying cell G 4 the input terminal 7 of the SSS circuit is also kept at + polarity: generator G goes on operating, independent of the polarity at the input terminal "

in " 20 msec after the beginning of the start element G gives a negative impulse via C 4, a positive one via C,, which makes point c even more negative and point d even more positive than in the rest condition, so this has no effect 30 msec after the beginning of the start element comes another positive impulse via C,, a negative one via C, As DS is now in the condition, point i has obtained, after some delay, dependent on the value of resistor R,, and of condenser C,, a positive polarity, and consequently so has point g At the moment the impulses occur point e becomes positive, point f remains positive and via G,, IV assumes for a moment the 70 + condition and via C, gives a positive impulse to Ca This impulse, however, is not large enough to make DS assume the + condition In Fig 7 is indicated for various points in the regenerative repeater, the magni 75 tude of the voltage as a function of the time, the voltage trend at point b can also be found here In contrast to the regenerative repeater of the British Patent No 709,901, where the circuit equivalent to DS had to remain 130 80 msec in the condition because there the tubes in the generator change their conductivity condition immediately at the beginning of the start element, and where consequently the impulse used as synchronization impulse 85 automatically has the correct polarity, in the present case special care must be taken that the impulse, 120 ursec after the first, has a polarity opposite to that of that first one in order to be suitable for synchronization As 90 appears from the above it is indeed attained by means of the indicated circuit, that after msec a positive impulse brings DS again in the + condition In the meantime the first sampling device (G, to G,, inclusive) has also 95 worked every alternative 20 msec, for the first time 10 msec after the beginning of the start element, and here the consecutive polarities of output terminal 4 of IS, which are also the polarities of elements of the incoming signal, 100 have been assumed by input terminal 7 of the output circuit U As the connecting of the terminals 5 and 7 has made U a trigger circuit, output terminal 4 of U assumes, each time during 20 msec, the polarity of the con 105 secutive signal elements; the signal is re-transmitted undistorted (Fig 7 bottom line) As we have seen already, DS re-assumes the + condition after 120 msec, and consequently so does IV Input terminal 7 of SSS now 110 becomes negative, independent of the polarity of the input terminal 1 For terminal 9 of DS becomes immediately negative and point r remains negative for a short time yet, thanks to condenser C 7 and resistor R,4,, thus causing 115 point a, too, to remain negative a bit longer, independent of the polarity of the input terminal 1 So the generator stops After an adjustable time (of magnitude determined by condenser CJ) point a is controlled again by 120 input terminal 1; if this terminal receives a negative voltage, the generator will start again,

but it does not operate so long as the input terminal is positive C 7 can be so adjusted that e g 135 msec after the beginning of the 125 start it is possible again to receive a fresh signal, which might be necessary in case signals are received from too fast a transmitter So in this case a stop element of too short a duration is transmitted In all other 130 785,357 cases it can be so adjusted that 140 msec after the beginning of the start a fresh signal can be received again and all elements are transmitted with a duration of 20 msec, except that when signals are received from a transmitter working at too low a speed, the duration of the stop element is lengthened by an amount equal to the difference in duration of a signal transmitted at too low a speed and the one transmitted at normal speed. This stopping and bringing again under the control of the input terminal is effected according to the same principle as the one mentioned in the British Patent Application No 29273/ 52 (Serial No 765,953) To effect that in the rest condition U cannot reach the condition, which cause polarity on the outgoing line, which e g might happen if markin, elements had been received continually, as may occur e g in the case of clearing signals, a so-called locking device has been provided wihich contains the rectifying cells GQ to G, inclusive. The operation of this locking device can be elucidated as follows:In the idle condition the rectifying cells G,,G, and G 7 of a relay cell with positive polarity are connected to points having positive polarity, for in that case IS is in the + condition, so even if the element received iast had a negative polarity, G, and G,, after a delay time (determined by R 5, and G), cannot but be at +, G, being connected with terminal 4 of DS, which terminal immediately becomes positive when the repeater stops So point j cannot but become positive and U is brought into the + condition via the rectifying cell G 8 During the start and during the further duration of the cyclus it is no longer true that G 5, G 6 and G 7 are all connected with points of positive polarity, and so the locking has ceased. It is also possible to effect the coming in of the signal into a polarized relay O in the usual manner, which polarized relay controls the armature o (see the left-hand bottom corner of Fig 7) The magnitude of the resistances can be chosen in such a manner that in the drawn position of the armature (idle condition) point q is positive and point p is negative; after the armature has moved over this is 50 reversed. The described circuit can be substituted for the input circuit IS (points p and q instead of points k and 1) to be connected to points m and n At the output the usual connection 55 with the line can be obtained by connecting to the output terminal 4 of U in Fig 6 a polarized relay Z w vhich controls the armature z at the beginning of

the outgoing line.

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