* GB785043 (A)

Description: GB785043 (A) ? 1957-10-23

Improvements in or relating to the sweetening of petroleum products

Description of GB785043 (A)

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BE533041 (A) DE965795 (C) FR1101183 (A) NL87496 (C) US2886521 (A) BE533041 (A) DE965795 (C) FR1101183 (A) NL87496 (C) US2886521 (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 785,043 Date of Application and filing Complete Specification: Nov 26, 1954. No 34400/54. Application made in France on Dec 19, 1953. Complete Specification Published: Oct 23, 1957; Index at Acceptance:-Class 91, 02 c. International Classification:-Cl Og. COMPLETE SPECIFICATION Improvements in or relating to the Sweetening of Petroleum Products. We, COMPAGNIE FRANCAISE DE RAFFINAGE, a body corporate organized under the Laws of France, of 11, rue du Docteur Lancereaux, Paris, France, 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: - The present invention relates to a process for sweetening petroleum fractions, and to compositions for effecting said process. In our British Patent Specification No. 701,443 and in our co-pending British Patent Applications Nos 16038/53 and 2803/54 (Serial Nos 767587 and 782052) there are described processes for sweetening petroleum products, and various preferred embodiments of these processes In general, these processes comprise effecting the desired sweeteningthat is, oxidation of mercaptan compounds which are usually present in petroleum fractions-in the presence of catalysts consisting of chelate organo-metallic compounds, such asthose obtained by the action of certain Schiff's bases on a metal salt, and in particular chelate compounds of cobalt with Schiff's bases resulting from the condensation of salicylaldehyde with a diamine In these processes the diamine might be aliphatic, cyclic, aromatic or hydroaromatic The chelate compound might be prepared and then added to the petroleum product, or might be formed in situ, and might be used in the presence of a solvent, such as an alcohol, ketone, phenol, or fatty acid, or in the form of an aqueous or aqueousalcoholic dispersion The process might be worked continuously, for instance by contacting the petroleum fractions with an excess of chelate compound in the form of such a dispersion, the dispersion being then separated and recycled In another alternative embodiment, the minimum sufficient quantity of a solution of the chelate compound was added to the petroleum fractions which then becomes sweet during storage Usually sufficient dislPrice 3 s 6 d l solved oxygen is present in the petroleum fractions to effect the -desired oxidation without additional air being blown in. It has now been found that the above described processes and their various embodi 50 ments can be improved, in respect of the ease of effecting a complete sweetening and of economy in the chelate compound used, by the use of a lead salt in admixture with said chelate compounds 55 Accordingly the present invention provides a process for the sweetening of petroleum fractions consisting in oxidizing mercaptans present in said petroleum fractions in the presence of a chelate organo-metallic com 60 pound and of' a lead salt The lead salts referred to in this specification are to be understood to include lead salts and alkali metal plumbites. Various preferred embodiments of the 65 process of the present invention differ from each other principally in respect of the conditions under which the lead salt is added to the petroleum fractions or to the chelate compound, and in respect of the mode of 70 preparation of the chelate compound, and may be characterised by particular combinations of these two factors Preferred embodiments of

the invention may comprise the features listed below, although it will be understood 75 that the invention is not limited to the application of these features. The lead salt used may be one which is soluble in hydrocarbons, such as a salt of an organic acid, a phenolate, or a mercaptide 80 The lead salt may be added together with the chelate compound, if desired with a solvent for the latter, to the petroleum fractions to be treated. Alternatively, there may be added to the 85 petroleum fractions, at the same time as the lead salt, a Schilf's base and a cobalt salt which will produce in situ the necessary chelate compound In this case, an aqueous alkaline solution may be present in order to 90 neutralise the acid generated by the formation of the chelate compound The alkali-for instance, caustic soda-may be present in stoichiometric quantity necessary to achieve neutralisation, or may, particularly in the case of continuous processes, be present in excess in relation to the quantity of acid generated at any particular time. Alternatively, the petroleum fraction together with the chelate compound already added or formed in situ, and, if desired, a solvent therefor, may be contacted with an alkaline solution containing a lead salt-that is, an alkaline solution of a plumbite. As a further alternative, the petroleum fraction containing a lead salt may be treated with an aqueous or aqueous-alcoholic dispersion of a chelate compound, for instance, prepared in situ in the aqueous or aqueousalcoholic medium by addition of a Schiff's base and a cobalt salt to the dispersion medium. The invention is further illustrated in a number of embodiments without limitative effect in the following examples, the first five of which are in the form of comparative experiments with the results tabulated to demonstrate the advantages achieved by the invention In the following examples, except Example VI, oxidation is effected by the oxygen dissolved in the petroleum fractions themselves. EXAMPLE I Eight parallel experiments were conducted on a mixture of straight-run and cracked petroleum spirit having a boiling range of 40 to 200 C and of S G 0 730, and containing 0.024 % by weight of sulphur in the form of mercaptans (herein abbreviated as SRSH) In the respective experiments there were added, to portions of the petroleum spirit mixture, the following additives, the amounts given being per litre of the portion of petroleum spirit in question: (a) 0 30 gms of cresol containing 10 % 45 of lead metal in the form of lead cresolate obtained by dissolving litharge in cresol. (b) 0 30 gms of cresol containing 10 %' of the chelate compound of cobalt with disalicylal-1, 2 propylene diimine 50 (c) 0 50 gms of cresol containing 10 , of the chelate compound used in (b) above.

(d) 0 20 grms of cresol containing 10 % of the chelate compound used in (b) above. (e) 0 30 gins of cresol containing 6 6 % of 55 lead metal in the form of lead cresolate and 6.6 % of the chelate compound used in (b) above. (f) 0 30 gms of cresol containing 10 % lead metal in the form of lead cresolate and 6 6 % 60 of the chelate compound used in (b) above. (g) 0 30 gmins cresol which acts as an oxidation inhibitor with respect to the gasoline. (h) nil (control). The respective portions were put in storage 65 and those containing the chelate compound and lead salt showed a progressive reduction of their mercaptan content concurrent with the formation of a precipitate of oxides of cobalt and/or lead which was readily separated 70 by filtration, leaving a petroleum spirit substantially free of metal compounds. Table I shows comparatively the results obtained in the various experiments in respect of the mercaptan-sulphur content remaining 75 after 24 hours, and of the stability as measured by the induction period calculated in accordance with the standard, A S T M No D 52549. TABLE I Additive reagents in gms/l Content of SRSH Wt in gms of -: of spirit (% by wt) sulphur oxidised Stability Tests by 1 gm of Induction Chelate Lead After chelate Period Cmpnd Cresol Metal Initial 24 hrs compound (a) 0 0 30 0 03 0 024 0 022 132 (b) 0 03 0 30 0 0 024 0 003 5 142 (c) 0 05 0 50 0 0 024 0 000 4 (d) 0 02 0 20 O 0 025 0 010 5 4 (e) 0 02 0 30 0 02 0 024 0 000 8 6 150 (f) 0 02 0 30 0 03 0 025 0 000 9 (g) 0 0 30 0 0 024 0 024 132 (h) O 0 0 0 024 0 024 58 It may be noted that the lead salt alone as an additive is practically without effect; that the chelate compound alone effects complete sweetening only if a sufficient amount, of the order of 0 05 gms/I in the above tests is used; and that the mixture of chelate compound and lead salt effects sweetening with a consumption of 0 02 gms of chelate compound per litre of spirit-that is, a saving of 60 as compared with the treatment without lead It will also be noted that the process in accord 105 ance with the present invention-for instance, test (e), improves the stability of the petroleum spirit. EXAMPLE II An Iraq kerosene having a boiling range of 110 785,043 and -without 10 % of lead metal in the form of lead cresolate. The results, shown comparatively in Table II, show the enhancement of the sweetening effect of the chelate compound which is effected by the presence of the lead salt. 196 to 257 C and S G 0 795, and an Iraq gas oil having a boiling range of 1920 to 371 C and S G 0 838 were treated in the same manner as in

Example I with 0 30 gins/1 of petroleum fraction of cresol containing 10 % bis-(disalicylal-ethylene diimine) dicobalt, with TABLE I Additive Reagents (gms/l of products) Chelate Cmpnd Lead Metal SRSE 5 (% by weight) Initial After 24 hrs. Wt in gins of Sulphur oxidised by I gmin of chelate compound 0.03 0 0 030 0 012 4 7 0.03 O 03 0 030 '0 000 8 0 0.03 0 0 030 O 015 4 3 0.03 O 03 0 030 0 000 8 6 After sweetening the products are decolourised with 1 part per thousand of adsorbing earth, or by washing with 20 % sulphuric acid The products are substantially free'of metal compounds. EXAMPLE Ill (a) To a straight-run Iraq petroleum spirit with a boiling range of 40 to 160 C and S.G 0 720, are added 3 cc/1 of methanol containing 10 gins/1 of salicylalpropylene diimino cobalt. (b) To a sample of the same spirit is added 1/40th of its volume of the same spirit washed by an alkaline solution of lithage thus obtaining a sample of petroleum spirit having approximately 1/40th of its mercaptan content combined as lead mercaptide To this' 40 sample is added 3 0 cc/1 l of methanol containing 10 gmins/l of the same cobalt chelate compound as in (a). (c) To a sample of the same petroleum spirit is added 0 014 gm/ 1 of lead metal in the form 45 of lead naphthenate, and then 3 cc/l of methanol containing 10 gms/l of the same cobalt chelate compound as in (a). The products are left in storage for 24 hours, and then filtered over sand It is 50 found, as will be seen from Table III, that complete sweetening is obtained only when the petroleum spirit has been treated with the cobalt chelate compound in the presence of a lead salt 55 TABLE III Additive Reagent SRSH Chelate Lead After Methanol Cmpnd Metal Initial 24 Lead Salt Present cc/1 gms/1 gms/l hours (a) 3 0 0 03 0 0 025 0 003 (b) 3 0 0 03 0 023 0 025 0 000 Lead in the form of mercaptide (c) 3 0 0 03 0 014 0 025 0 000 Lead in the form of naphthenate EXAMPLE IV This example will illustrate embodiments in which a cobalt chelate compound is formed in situ. Three parallel experiments were conducted with a straight-run petroleum spirit of Middle East origin, having a boiling range of 40 to C and S G 0 728, and containing no free sulphur In the respective experiments there is added, per litre of spirit:(a) 0 015 gins 1, 2 dislicylal-propylene diimine and 0 0032 gins of cobalt in the form of cobalt naphthenate. ( 5) 0 015 gins 1, 2 disalicylal-propylene diimine 0 0032 gms of cobalt in the form of 80 cobalt naphthenate, and 0 047 gms of lead metal in the form of lead mercaptide. (c) 0 015 gins disalicylal-1, 2 propylene diimine O 0032 gins of cobalt in the form of cobalt naphthenate, and 0 028 gins of lead 85

metal in the form of lead naphthenate. After standing for 24 hours, the respective samples are filtered and the mercaptan contents determined The results, as shown in Table IV, clearly illustrate the enhanced 90 activity, due to the presence of the lead salt, of the chelate compound formed in situ by the action of the' Schiff's base on the cobalt salt. Product treated Iraq Kerosene Iraq Gas Oil 785,043 785,043 TABLE IV Additive Reagents SRSH (% by wt) (grnsll of Spirit) Wt in gms of sulphur oxidised Lead Salicylal Cobalt After by 1 gin of chelate Metal diimine Naphthenate Initial 24 hrs compound. (a) O 0 015 0 0032 0 025 0 015 4 0 (b) 0 047 0 015 0 0032 0 025 0 003 8 8 (c) 0 028 0 015 0 0032 0 025 0 004 8 4 EXAMPLE V Example IV, but in the presence of 25 cc/1 of In this example also, the cobalt chelate spirit of 10 % caustic soda The results compound is formed in situ obtained for the respective quantities of The same petroleum spirit as in Example IV additive reagents used are summarised in is treated with the same additive reagents as in Table V: TABLE V Additive Reagents (ginsl/1 of spirit) Sn SH (% by wt) Wt in gms of Lead Salicylal Cobalt 10 % After sulphur oxidised Metal diimine (Naphthenate) Na OH Initial 24 by 1 gin chelate (gins) (gms) (gins) (cc) hrs compound 0 0 0075 0 0016 25 0 025 0 010 12 0.047 0 0075 0 0016 25 0 025 0 003 17 5 0.028 0 0075 0 0016 25 0 023 0 002 16 5 0.028 0 0150 0 0032 25 0 025 0 0005 10 0 0 015 0 0032 25 0 025 0 004 8 4 These data show that in the absence of a lead salt, the mercaptan content is only moderately reduced On the other hand, the mixture of the lead salt with the cobalt chelate compound effects the reduction of the mercaptan content to a copper number of 4 without additional consumption of chelate compound, and even effects substantially complete sweetening The favourable action of the caustic soda in this case when a cobalt chelate compound is formed in situ will be noted by a comparison of these results with those in Example IV. EXAMPLE VI In a continuous process, there were injected into a petroleum spirit of boiling range of 40 to 2005 C and S G 0 730, successively per cubic m thereof, 7 5 gins of disalicylal-1, 2 propylene diimine and 1 6 gins of cobalt in the form of cobalt acetylacetonate to form a cobalt chelate compound. The resulting mixture was contacted in a mixer with simultaneous injection of air with 1/10th of its volume of 10 % caustic soda in which were dissolved 3 5 gins/1 of litharge. The aqueous phase is separated in a decanting vessel and recycled to the mixer. In this manner were treated 70 litres of a petroleum spirit containing 0 025 %c by weight of sulphur in the form of mercaptans, and having

had added thereto 100 cc of Na OHplumbite solution. The petroleum spirit product obtained had a copper number of 3. EXAMPLE VII An aqueous dispersion of the cobalt chelate compound of disalicylal-1, 2 propylene diimine is prepared by adding stoichiometric 70 quantities of soda, disalicylal-1, 2 propylene diimine and cobalt nitrate, to a mixture of %, by volume of water and 10 % by volume of a commercial solution of the wetting agent marketed under the Registered Trade Mark 75 "Teepol " In this manner, a stable aqueous dispersion containing 1 % of the chelate compound was obtained. One litre of straight-run Iraq petroleum spirit having a final boiling point of 200 C 80 and S G 0 720, and containing 0 025 % by weight of sulphur in the form of mercaptan, is agitated for 3 minutes with 3 cc of the above-described 1 %, dispersion of chelate compound, and is then allowed to settle After 85 standing for 24 hours, the mercaptan content had dropped to 0 012 % O SRSH. A parallel experiment was conducted with the same quantities of reagents but in which previously 0 02 gm/l of lead metal in the form 90 of lead cresolate had been added to the petroleum spirit After 24 hours, the petroleum contained only 0 002 % S Rs H. EXAMPLE VIII An aqueous-alcoholic solution of the chelate 95 compound of cobalt with disalicylal-1, 2 propylene diimnine containing 6 gins/1 of the chelate compound and 100 cc of methanol per litre, is prepared. (a) 250 cc of this solution is used to treat 100 in hydrocarbons. 4 A process as claimed in claims 1 or 3, characterised in that the chelate compound is introduced into the petroleum fraction in solution in a solvent miscible with the said 70 petroleum fraction, such as an alcoholy, a ketone, a phenol, or a fatty acid, said solution also containing the lead salt soluble in hydrocarbons, such as the salt of an organic acid, a phenolate or a mercaptide 75 A process as claimed in any one of claims 1 to 3, characterised in that the petroleum fraction to which a cobalt salt, a Schif F's base and the lead salt have previously been added, is brought into contact with an aqueous 80 alkaline solution. 6 A process as claimed in any one of claims 1 to 3, characterised in that the petroleum fraction to which a cobalt salt and a Schiff's base have been previously added, is 85 brought into contact with an alkaline solution containing a mineral salt of lead. 7 A process as claimed in claims 1 or 3, characterised in that the petroleum fraction to which a lead salt has previously been added is 90 treated with an aqueous dispersion of a chelate compound of cobalt. 8 A process as claimed in claim 7, characterised in that the said dispersion is prepared by adding a cobalt salt and a Schiff's 95 base

to an aqueous solution of a surface active agent. 9 A process as claimed in claims 1 or 3 characterised in that the petroleum fraction, to which a lead salt has previously been 100 added, is treated with an aqueous-alcoholic dispersion of a chelate compound of cobalt. A composition to be added to a petroleum fraction, for the purpose of sweetening the same, consisting of a mixed 105 solution of a chelate organo-metallic compound and a lead salt.

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* GB785044 (A)

Description: GB785044 (A) ? 1957-10-23

Electro-plating apparatus of the rotary-barrel type

Description of GB785044 (A)

PATENT SPECIFICATION Inventor:-ALFRED JAMES LESTER NASH. Date of filing Complete Specification: Nov 23, 1955. Application Date: Dec 15, 1954 No 36268154. Complete Specification Pitliilied: Oct 23, 1957. Index at Acceptance:-Class 41, A 1 A. International Classiiication:-C 23 b. COMPLETE SPECIFICATION. Electro-Plating Apparatus of the Rotary-Barrel Type. We, R CRUICKSHA Nic LIMITED, of Camden Street, in the City of Birmingham 1, a British Company, 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 has for its object to provide in an improved form an electroplating apparatus of the rotary-barrel type. An apparatus in accordance with the invention comprises a frame adapted to be supported on a tank and movable vertically into and cut of the tank, a pair of barreldriving rings adapted to be secured to the ends of the barrel, rollers on which the said rings are suspended, driving mechanism for the rollers comprising a source of motion mounted on the tank and gearing mounted on the frame and detachably engageable with the said source of motion, and steady pieces supported by the frame for engagement with the ends of the barrel. In the accompanying drawings:Figure 1 is a sectional front elevation of an apparatus embodying the invention; and Figure 2 is an end elevation; Figure 3 is an end elevation of the lower portion of one of the depending side members of the frame; Figure 4 is an end view of one of the barrel-driving rings; Figure 5 is a front elevation of an alternative arrangement of the barrel-driving mechanism. Referring to Figures 1-4 of the draw; ings, the frame consists of a horizontal upper member a, and a pair of depending side members b The upper member is adapted to extend across and to be supported on the upper edges of a tank c, by a pair of laterally extending cylindrical pegs d lPrice 3 s 4 g 785,044 secured at a distance apart on each end of this member and arranged to be supported by forked sockets e secured to the ends of the tank At the underside of and parallel with the upper member of the frame is supported a shaft f, this being carried by bearings g attached to the said member On this shaft is secured a pinion h which engages another pinion i on a shorter shaft j which is also carried by the said member, and which extends beyond one end of the tank On the outer end of the second shaft j is secured another pinion k which engages a pinion m driven by an electric motor n through a belt o and pulleys p, and reduction gearing q, the motor and reduction gearing being supported on a bracket r secured to the outer side of one of the end walls of the tank The arrangement is such that when the frame is in its operative position, the end pinion k on the shaft j engages the motor-driven pinion and so transmits motion to the shaft f But when the frame is raised the said pinion on the shaft j is raised out of engagement with its associated driving pinion Raising and lowering of the frame is effected in any convenient manner such as by an overhead lifting tackle attached to a hook on the upper member of the frame. On each end of the shaft f is secured a roller S and on these rollers are suspended a pair of coaxial rings t which are secured to the ends of the barrel u by diametrical straps v and screws as shown in Figures 1 and 4 The rollers and rings may cooperate frictionally, but if desired each roller may be a toothed pinion, in which case each ring

is internally toothed. To prevent lateral swinging of the barrel relatively to the rollers, when the barrel is being rotated, there is formed in the centre of (G 5 753 so 785,044 each end of the barrel ends a hole into which enters one end of a steady piece W shaped as shown in Figures 1 and 3 The said end of the steady pieces is of cylindrical form A 5 and is made of rather smaller diameter than the hole Tihe other end of the steady piece is of rectangular form and enters into the adjacent side member b of the frame, the said member being constructed from a pair of parts which form between them a guide for the said end of the steady piece as shown in Figure 3 The arrangement is such that the steady pieces serve only to prevent swinging of the discs and barrel when in motion, and sufficient clearance is provided between them and the holes to permit at all times effective driving contact between the above described rollers and rings, irrespective of normal wear or the 2 ' accumulation of deposits on the rollers or disc flanges. The cathodes consist of electrically insulated flexible conductors x which are inserted into the barrel through central holes -5 in the steady pieces The free ends of the conductors lie in contact with the lower part of the barrel, and their outer ends are secured to terminals on the upper member of the frame The anodes (not shown) con3, sist of a series of metal plates, either flat or bent to a semi-circular form suspended by means of metal hooks from suitably placed anode rods. In an alternative form of that part of the 3.5 barrel-driving mechanism which is mounted on the frame, the arrangemnent shown in Figure 5 may be used In this case the shaft j which receives motion from the motor through the pinion k, is extended and is provided with two pinions i which engage pinions hz, the latter being secured to a pair of short shafts f which carry the rollers s. By this invention the mechanism required for rotating the barrel in the tank is provided in a very simple and robust form which is unaffected by normal wear or by the accretion thereon of metallic or other deposits derived from the tank.

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* GB785045 (A)

Description: GB785045 (A) ? 1957-10-23

Purification of terephthalic acid

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COMPLETE SPECIFICATION Purification of Terephthalic Acid We, IMPERIAL CHEMICAL INDUSTRIES LIMITED, of Imperial Chemical House, Millbank, London, S.W.1, England, a British Company, 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 the purification of terephthalic acid. In the preparation of terephthalic acid by the oxidation of para-substituted aromatic compounds such as para-xylene, the crude terephthalic acid contains small quantities of coloured impurities. When using terephthalic acid in the manufacture of fibre and film-forming polyesters it is essential that the terephthalic acid used be free of coloured impurities, as far as is practically possible, in order to obtain polyesters having good colour. According to the present invention, we provide an improved process for purifying crude terephthalic acid, which comprises heating terephthalic acid under pressure with water containing an oxidising agent having no oxidising effect on the terephthalic acid itself, preferably a manganese or chromium compound, continuing the heating until solution occurs, cooling the resultant solution and allowing terephthalic acid to crystallise out.

In the preferred process of our invention, we heat the crude terephthalic acid in water containing the oxidising agent to a temperature above 200 C., as the solubility of terephthalic acid in water above 200 C. increases rapidly. We have found that permanganic acid derivatives, especially potassium and sodium permanganates, chromic acid and derivatives of chromic acid, or manganese dioxide or mixtures of these compounds are very suitable oXidsing agents as they are readily available and have no effect on the terephthalic acid but only on the impurities. If desired, a first purification may be made using a simple recrystallisation of the crude acid from water under pressure before subjecting the terephthalic acid to a further purification by the process of our present invention. We have also found that if the crude terephthalic acid is first treated in aqueous solution under pressure with a reducing agent, which does not reduce the terephthalic acid itself, the impurities in the terephthalic acid are more readily oxidised by the subsequent oxidation treatment As examples of reducing agents, we have found such substances as sodium hyposulphite, titanous sulphate, sulphur dioxide, hydrogen sulphide, nascent hydrogen and phosphorous acid are very suitable. A sample of crude terephthalic acid was twice crystallised from a 4% solution in water at 2400 C. The optical density of the product in 4% ammonia solution was 0.36. The optical density is an arbitrary figure based on 0.00 for 4% ammonia alone and measured at a wavelength of 380 x 10-r centimetres. The following examples, in which all percentages are by weight illustrate the superior results obtained by, but do not limit, our invention:- EXAMPLE 1 A further sample of the same crude terephthalic acid referred to hereinbefore was twice crystallised from a 4% solution in water at 240 C. but on the second occasion 0.1% potassium permanganate was added to the water and the solution made slightly acid by the addition of 1% sulphuric acid. The optical density of the product was 0.26. EXAMPLE 2 The process of Example 1 was repeated using 0.1% manganese dioxide instead of potassium permanganate. The optical density of the derived terephthalic acid was 0.30. EXAMPLE 3 The process of Example 1 was repeated using 0.1% sodium permanganate. The optical density of the product was 027. EXAMPLE 4 The process of Example 1 was repeated using a solution containing 0.1%

of sodium dichromate instead of the permanganate. The optical density of the derived terephthalic acid was 0.30. EXAMPLE 5 The process of Example 4 was repeated using 0.1% potassium dichromate. The optical density of the derived terephthalic acid was 0.29. EXAMPLE 6 The process of Example 4 was repeated using 0. 1% chromium trioxide in place of sodium dichromate. The optical density of the derived terephthalic acid was 0.31. EXAMPLE 7 Another sample of the crude terephthalic acid used in Example 1 was first crystallised from water in a 4% solution, the solution also containing 0.1% titanous sulphate. The optical density measured as before gave a value of 1.5. When the product was crystallised a second time from 0.1% potassium permanganate solution, the resultant optical density was 0.04. EXAMPLE 8 The process of Example 7 was repeated using nascent hydrogen as the reducing agent which was generated from zinc and sulphuric acid. The optical density of the derived terephthalic acid was 0.09. EXAMPLE 9 The process of Example 7 was repeated using 0.1% sodium hyposulphite in place of titanous sulphate followed by oxidation using 0.1% potassium dichromate in place of potassium permanganate. The optical density of the derived terephthalic acid was 0.07. EXAMPLE 10 The process of Example 9 was repeated using 0.1% of stannous chloride in 1% hydrochloric acid as the reducing agent. The optical density of the derived terephthalic acid was 0.15. EXAMPLE 11 The process of Example 9 was repeated, the terephthalic acid being initially crystallised from water containing 0.1% of sulphur dioxide. The optical density of the derived terephthalic acid was 0.28. EXAMPLE 12 The process of Example 9 was repeated, the terephthalic acid being initially crystallised from 1% phosphorus acid. The subsequent oxidation was with potassium permanganate. The optical density of the derived terephthalic acid was 0.03. Although the reducing agent when combined with the oxidising agent, gives such a useful improvement we have found that no appreciable improvement is obtained using a reducing agent on its own. The improvement obtained in the colour of the terephthalic acid is clearly reflected in the improved colour of polyesters made from the terephthalic acid.

What we claim is: - 1. A process for purifying terephthalic acid which comprises heating terephthalic acid under pressure with water containing an oxidising agent having no oxidising effect on the terephthalic acid itself, continuing the heating until solution occurs, cooling the resultant solution and allowing terephthalic acid to crystallise out.

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* GB785046 (A)

Description: GB785046 (A) ? 1957-10-23

Acetone soluble copolymers

Description of GB785046 (A)

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

DE1063805 (B) FR1138947 (A) US2855389 (A) DE1063805 (B) FR1138947 (A) US2855389 (A) less Translate this text into Tooltip

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0,, Cs & 'l V

PATENT SPECIFICATION Inventor: ANTHONY SPARKS Date of filing Complete Specification: Nov 23, 1955. Application Date: Dec24, 1954 No 37388/54 7 Complete Specification Published: Oct 23, 1957. Index at acceptance:-Class 2 ( 6), P 8 D( 3 A: 8), P 8 (F 1: K 10), P 8 P 1 E( 1: 3), P 8 P 2 (AS: X), P 1 OD( 1 A: 2 A; 8), P 10 F 1, PI O K( 8; 10), PI O P 1 E( 1:3), P 10 P 2 (A 5: X). International Classification:-C 08 f. COMPLETE SPECIFICATION Acetone Soluble Copolymers We, THE DISTILLERS COMPANY LIMITED, a British Company, of 12, Torphichen Street, Edinburgh 3, Scotland, 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: - The present invention relates to, improvements in or relating to the production of vinylidene chloride/acrylonitrile copolymers. In particular it relates to the production of such copolymers which are readily dissolved in acetone which May, if necessary, be heated to aid the solution of the polymer. lit has been stated that when vinylidene chloride and acrylonitrile are copolymerised in a system in which the monomers are present in aqueous emulsion or suspension, the initial ratio of water to total monomers being between 5:1 and 10:1 by weight and the initial molar ratio of vinylidene chloride to acrylonlitrile being between 3: 1 and 1: 3, acetone-soluble polymers of good quality can be obtained without the necessity of adding the acylonitrile in stages or progressively removing unreacted vinylidene chloride From such mixtures the resultant acetone-soluble copolymers have contained proportions of combined vinylidene chloride ranging from less than 50 % to over 80 % by weight. It has further been stated that acetonesoluble copolymers are obtained by replacing a part of the vinylidene chloride with vinyl chloride in the copolymerisation of vinylidene chloride and acrylonitle Copolymers containing from 10 to 60 % by weight of combined vinyl chloride and 50 to 20 % by weight of combined acrylonitrile, the remainder being vinylidene chloride are said to be acetonesoluble. It has now been found that in the preparlation of vinylidene chleride/acrylonitrile copolymers which are acetone-soluble emulsion polymteri ation techniques although giving lPrice Ad g Q good products, suffer from the practical disadvantage that the recovery of the product is comparatively difficult owing to the emulsified form in which lit is produced In particular the emulsion has to be broken before the product can be recovered by normal methods and moreover it

is difficult to ensure removal of the emulsifying agent. The usual suspension polymerisation procedures, in which the polymnerisation takes place in the dispersed monomer-phase, give rise to polymers in the form of beads which are therefore easily recoverable in a pure state However, they suffer from the disadvantage that ithey 'are not completely homogeneous They contain small portions of material which are not easily dissolved in acetone and, in some cases, are insoluble in acetone. An object of the present invention is to provide an improved process for the production of acetone-soluble copolymers from vinylidene chloride and acrylonitrile A further object is to provide a process in which the relarive proportions of the two monomers entering the copolymer may be readily controlled. Accordingly the present invention provides a process for the production of copolymers in the form of beads which comprises suspending a monomeric mixture comprising vinylidene chloride and acrylonitrile in such proportions that the resultant copolymer is soluble in acetone, throughout an aqueous phase containing an inorganic suspension stabilisers and sufficient quantities of a dissolved salt to reduce subseantally the solubility of acrylonitrile therein, and polymerising the suspended monomeric mixture at an elevated temperature with the aid of a monomer-soluble polymerisation catalyst. The vinylidene chloride and acrylonitrile May be present in any proportions which are knoiwn to give acetone-soluble products, for instance, the proportion of combined vinyl785046 v I q G ' 785,046 idene chloride in the copolymer may range from less than 50 % to over 80 % by weight If desired, some of the vinylidene chloride may be replaced with vinyl chloride or some other suitable copolymerisable monomer to give ternary copolymers which are soluble in acetone When the third component is vinyl chloride acetone soluble copolymers contain, for instance, 10 to 60 % by weight vinyl chloride units and 50 to 20 % by weight acrylonitrile units, the remainder being vinylidene chloride units The solubility of a copolymer of vinylidene chloride and acrylonitrile in acetone depends, inter alia, upon its constitution It is also well established that the constitution of a copolymer depends not only on the proportion of the monomers present in the monomer mixture from which it is formed, and their relative reactivities, but also on the degree to which the copolymerisation is allowed to proceed It is thus possible to vary the acetone solubility of a copolymer produced by the process of the present invention from a given monomer mixture by varying the degree of polymerisation which occurs. From the wide ranges of acetone-soluble copolymers which can be

produced by the process of the present invention particularly valuable copolymers for the production of films and fibres are those consisting essentially of vinylidene chloride and acrylonitrile units in which the latter are present in a proportion by weight of (about 40 % to 50 %. If the proportion of acrylonitrile units is increased above about 50 %, the acetone solubility of the product is reduced, while if it is reduced below 40 % those advantageous properties of the copolymer which make it valuable in the manufacture of films 'and fibres are diminished Particularly valuable copolymers contain about 480 % by weight of acrylonitrile units. The process of the present invention is particularly useful for the preparation of copolymers having acrylonitrile contents between 40 and 50 % by weight and it is found that there is no need to adopt special techniques such as adding the components at different rates to the polymerising suspension in order to obtain good yields of the desired products They are formed most economically by the process of the present invention with the minimum wastage of unpolymerised monaers by starting with 100 parts by weight of a monomer mixture containing from 50 to 60 parts by weight of vinylidene chloride and from 50 to 40 parts by weight of acrylonitrile A preferred monomer mixture contains about 55 parts by weight of vinylidene chloride and about 45 parts by weight of acrylonitrile. The volume of the aqueous phase in relation to the monomer mixture can be varied as is well known in connection with aqueous suspension polymerisation systems Most conveniently the polymerisation system should contain from 1 to 3 volumes of aqueous phase per volume of monomer mixture. Any of the known inorganic suspension stabilisers which have hitherto been suggested for 70 use in the polymerisation of vinyl monomers may be used in the process of the present invention provided that it does not react with, or become inactivated by, the dissolved salt present in the aqueous phase Particularly good 75 results are obtained when finely divided magnesium hydroxide is used as suspension stabiliser The quantity of stabiliser used may be varied considerably as is well known in the art of suspension polymerisation Generally it 80 is preferred to use as small a quantity of stabiliser as possible having regard for the stability of the suspension and, for instance, when magnesium hydroxide is employed, the preferred weight of stabiliser is about 0 5 % 85 by weight on the water in the aqueous phase which is present in about 1 to 3 volumes per one volume of monomer mixture. It is known that the addition of soluble salts such as sodium chloride to water re 90 duces the amount of acrylonitrile which can be dissolved therein at any given temperature.

In the process of the present invention sufficient quantities of such a salt are added to the aqueous phase of the suspension polymnerisa 95 tion system to reduce substantially the solubility of the acrylonitrile therein It is preferred that the amount of the salt added shall be such that the solubility of the acrylonitrile in the aqueous phase at the temperature of the 100 polymerisation is at least halved The precise amount of salt employed will depend on the nature of the product it is desired to produce and polymerisation conditions employed; by varying the amount of salt employed consider 105 able control of the copolymerisation reaction and product can be achieved. Often it is convenient to use a nearly saturated salt solution but care has to be taken to ensure that no difficulties arise due to crystal 110 lisation of the salt from the aqueous phase either during the polymerisation or subsequently during the processing of the resultant bead suspension should the temperature thereof be reduced Particularly good results 115 are obtained by using sodium chloride as the salt dissolved in the aqueous phase. The copolymerisation of the monomeric mixture containing the vinylidene chloride and the acrylonitrile is brought about in the usual 120 manner by the addition thereto of a monomer-soluble polymerisation catalyst after which the mixture is heated By ia monomersoluble catalyst is meant a catalyst which is considerably more soluble in the monomer 125 than in the water phase The preferred catalysts are substantially insoluble in the aqueous phase and, as examples, may be mentioned the substantially water-inseluble organic peroxides such as benzoyl peroxide, ortho-chlorbenzoyl 130 cess of the present invention. EXAMPLES 1-8. In each of these examples 275 grams of vinylidene chloride were mixed with 225 grams of acrylonitrile and 1 0 % of benzoyl peroxide was added This oil phase was dispersed in 1250 millilitres of water containing varying quantities of dissolved sodium chloride (see tables below) and 0 5 % by weight on the water present of magnesium hydroxide which had been formed in situ by the addition of sodium hydroxide to magnesium chloride in solution The suspension Was maintained by the action of a stirrer rotating at 400 r.p m and polymerisation was brought about by heating the suspension to an elevated temperature and for the periods indicated in the table below In all the examples nitrogen was used to displace oxygen from the polymerisation vessel and in some cases the polymerisation was carried out under super atmospheric pressures. At the end of the polymerisation period the suspension was discharged from the reaction vessel and well washed with water The beads were then washed with dilute hydrochloric acid solution and stirred for 30

minutes to remove any residual magnesium hydroxide The beads were finally washed with water until free from chloride ions and then dried in a vacuum oven at 50 to 60 C The results obtained are shown in the following table: peroxide and aluryl peroxide. The temperature at which the copolymerisation is carried out may be varied considerably depending ion the rate of polymerisation required, the amount of polymerisation catalyst employed and the physical properties it is desired that the final product should possess. If temperatures above the boiling points of any of the components of the system are used, super atmospheric pressures have to be employed in order to maintain the liquid phases. Most suitably tthe polymerisation is carried out at a temperature it the range 40 to 90 ' C. As is customary in polymerisation reactions it is preferred to carry out the polymerisation in the absence of molecular oxygen and this is most suitably achieved by displacing the air in the polymerisation vessel with an inert gas such as nitrogen Preferably the inert gas is employed at a super atmospheric pressure. The copolymer beads produced by the process of the present invention are recovered and washed by any of the usual techniques. The products are particularly useful for the production of acetone solutions from which films and fibres of the vinylicdene chloride/ acrylonitrile copolymers can be prepared by any of the known wet casting or spinning techniques. The following examples illustrate the proWt of Na Cl Nitrogen Polymerisation % by weight in aqueous pressure of acryloExample phase in in lbs / Temp Time Yield nitrile units grams sq in C Hrs % in copolymer 1 475 Atmos 70 4 74 6 43 9 pheric 2 425 Atmos 70 4 84 3 44 4 pheric 3 425 Atmos 65 4 85 44 0 pheric 4 400 Atmos 70 4 82 1 45 6 pheric 400 20 70 5 81 7 44 6 6 400 40 70 2 5 78 9 44 3 7 400 60 70 5 82 9 44 9 8 400 Atmos 65 5 80 1 44 5 pheric In all the above examplest the product was in the form of yellowish-white beads which readily dissolved in acetone to give solutions from which films and fibres were produced by known procedure The yield is indicated in a percentage of the theoretical yield. When the same relative quantities of monomers were copolymerised under similar con785,046 ditions using a suspension process in which an inorganic stabiliser was employed in the absence of a dissolved salt in the aqueous phase or in which an organic stabiliser was employed inferior products were obtained which were not so completely soluble in acetone and which had slightly lower acrylonitrile unit contents Such products were also inferior with regard to their spinning properties.

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* GB785047 (A)

Description: GB785047 (A) ? 1957-10-23

Anhydrotetracycline compounds

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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.

COMPLETE SPECIFICATION Anhydrotetraeycime Compound We, CHAS. PFIZER & CO., INC., a corporation organized and existing under the laws of the State of Delaware, United States of America, located at 11 Bartlett Street, Brooklyn 6, State of New York, 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 is concerned with a method of converting certain antimicrobially active agents to the corresponding anhydro compounds. This invention is also concerned with the products obtained by this reaction. The prcduct orrnea by thel loss of one molecule of watsc from the structural unit of certain pclycyclic oxygenated compounds

from the class generally referred to as tetracyclines. It has now been found that not only does oxytetracycline undergo this unique dehydration reaction, but in exactly the same manner Anhydrodesdimethylaminooxytetra cycline Anhydrodiacetyloxytetracycline Anhydrodesdimethylaminodesoxyoxy- tetracycline Anhydrodesdimethylaminochlortetra cycline Anhydrodesdimethylaminotetracycline Anhydromethomycin Anhydroisodesdimethylaminooxytetra- cycline The dehydration reaction of the present invention may be brought about by dehydrating agents, particularly acidic compounds. For some unknown reasons this results in the formation of the new compounds which have appreciably different types of activity against microorganisms from that of the parent compounds. This result is not a mere certain other compounds may be dehydrated to yield new products which are microbiologically active. Most unusual is the fact that there is often appreciable change in the antimicrobial spectrum of the product formed as compared to the starting materials. This change in the nature of the spectrum may be due to a characteristic change in the structural configuration of the product as compared to the starting materials. In the following table is given the names of the anhydro compounds (referred to herein as"anhydrotetracycline compounds") together with the apparent structure of some of these compounds which are made by the process of the present invention : <img class="EMIRef" id="026415687-00010001" /> R1 R2 R3 R4 H OH H OH CH3)2 OAc H OAc H OH H H H Cl OH H OH H CH,, H H Cl OH H H H OH H OH H CH3 H OH H OH (trans) quantitative change, but a change in which the product is active against organisms which are but slightly affected or not affecte at all by the parent compound. Furthermore, the dehydrated compounds have somewhat different chemical properties from the parent products. This is particularly true with respect to stability of the new compounds which often tend to be higher than that of the parent

compounds. Among the agents which are effective in bringing about the dehydration process of this invention are mineral acids such as sulfuric acid, hydrochloric acid, hydrobromic acid, phosphoric acid and various anhydrides of these compounds. Acid salts such as potassium acid sulfate, sodium acid sulfate, and sodium dihydrogen phosphate are also effective. Organic acids are found to be effective for bringing about this process, such as benzene sulfonic acid, toluene sulfonic acid and chloracetic acid. The reaction may be effected in aqueous solutions in the presence of the various acid dehydrating agents, but it is often preferred to use conditions involving the presence of a minor proportion of water or none at all in the reaction mixture. The use of a stable polar organic solvent is particularly effective with acid dehydrating agents. Among the combinations which are favored are anhydrous hydrogen chloride in menthanol, anhydrous hydrogen chloride in acetone, concentrated sulfuric acid in dimethylformamide and hydrogen chloride in acetic acid. It is obvious that care must be exercised in conducting the reaction to assure that extensive decomposition does not occur after the dehydration reaction has been brought about, thus the proportion of concentrated sulfuric acid in a solvent must be adjusted so that extensive decomposition does not prevail. It is relatively easily determined just what the best conditions for the use of a specinc reagent are. In general, we prefer to use temperatures of not greater than about 50 C., although appreciably lower temperatures are often advisable with the more sensitive compounds and with more destructive acids. In some cases it is possible to use boil- ing dilute solutions of mineral acids in water or a solvent. The combination of acetone and anhydrous hydrogen chloride has been found particu- larly effective in the preparation of the anhydro compounds. The product formed may be isolated in consiste ^, good yield, and, furthermore, there are formed novel inter- mediate compounds. These consist of one molecule of acetone combine in a unique manner with the anhydro compound. The acetone derivatives are forms in which the anhydro compounds may be most readily isolated in a high state of purity, often in crystalline form, and they are readily converted to the free anhydro compounds by treatment with aqueous acid. It is often advisable to concentrate the reaction mixture preferably at moderate temperature under a vacuum after completion of the reaction. In this way the crystalline acetone derivative is generally obtained direcdy from the concentrated reaction mixture. Other acids than hydrogen chloride may be used in acetone to form the anhydro compounds as their acetone derivatives, but these other acids do not possess the advantage of high volatility permitting their ready

evaporation and isolation of the acetone derivatives in highly pure, often crystalline form. In carrying out the present process a dilute solution of the parent compound, that is the tetracycline compound is used. By a dilute solution is meant a concentration of 0. 1 gm. per 100 ml. of solution or more. Concentrations of as high as about 20% and even lower than 0. 1 gm./100 ml. may be used if desired. In general, at least one mole of acid per mole of tetracycline compound is used. An excess of the acid over this proportion is useful particularly if the parent compound has a basic group, that is a dimethylamino group. The anhydro product may often be isolated by diluting the reaction mixture with water and neutralizing the acidic reagent. Alternatively the acid may be neutralized and the solid separated, if insoluble in the reaction medium. If the product is soluble, the solvent may be removed, for example, by evaporation, to obtain the solid product. The anhydro compounds have a limited solubility in water at pH's slightly below the neutral range, that is between about 4 and about 7. However, if the product does not separate from solution, the neutralized solution may be concentrated, preferably at moderate or low temperatures, that is not over about 50 C., to cause the product to separate. A second method of obtaining a dry product is to freeze the aqueous solution and dry it under vacuum. Certain solvents may be used for extracting these products from aqueous solution, particularly at approximately neutral pH's. These include such polar organic solvents as water immiscible aliphatic alcohols, for example, butanol and amyl alcohol and benzyl alcohol. The solvent extract may then be concentrated or evaporated to dryness. Alternatively an aqueous concentrate may be obtained by extracting the alcohol solution with dilute acid in a small volume. The aqueous concentrate is then adjusted to approximately neutral pH to precipitate the product. The products may be isolated in the form of salts with acid used for dehydration or they may be prepared from the amphoteric compounds and a suitable strong acid (e. g. hydrochloric acid and sulfuric acid). Furthermore, salts may be prepared from the amphoteric compounds with strong bases such as those of alkali metals and alcaline earth metals. The products obtained by the process of the present invention are new compounds. They are solid, yellow, often crystalline materials. They may be recrystallized from lower alcohols having from 1 to 4 carbon atoms or from lower alcohols with water or ether. In the following table is given the micro biological activity of representative samples of the anhydrotetracycline type compounds whose

preparation and properties are described above. Anhydrodesdi-Anhydrodesdi-Anhydro methylamino-methylamino-diacetyl oxytetra-chlortetra-oxytetra cycline cycline cycline A. aerogenes (AC 2) 12. 5 50. 0 100. 0 MT 2 12. 5 1. 56 PI 12. 5 parent 50. 0 100. 0 50. 0 E. coli 50. 0 100. 0 100. 0 Proteus 50. 0 100. 0 100. 0 Pseudomonas sp. 100. 0 100. 0 100. 0 Candida albicans 50. 0 100. 0 100. 0 Salmonella typhosa 50. 0 100. 0 100. 0 K. pneumoniae 25. 0 50. 0 100. 0 Sal. paratyphi A 25. 0 100. 0 100. 0 Sal. paratyphi B 50. 0 100. 0 100. 0 Staph. aureus 50. 0 0. 19 1. 5 Str. faecalis 50. 0 0. 19 3. 1 Brucella bronchiseptica 50. 0 0. 78 12. 5 B. subtillis 25. 0 0. 19 1. 5 Ps. aeruginosa--- Myco. ranae 12. 5 0. 39 12. 5 smegmatis 12. 5 0. 19 12. 5 phlei 12. 5 0. 19 12. 5 No. 607 12. 5 0. 19 12. 5 berolinense 12. 5 0. 78 PI 25. 0 butyricum 12. 5 0. 78 PI 12. 5 The following examples are given by way of illustration only and are not to be considered as limitations on the scope of this invention, which is to be limited by the appended claims only. EXAMPLE I. Anhydrodesdimethylaminochlortetracycline -One and one-half grams of pure desdimethylaminochlortetracycline in 60 ml. of 50% dioxane-methanol was treated with 60 ml. of saturated methanolic hydrogen chloride solution, carefully filtered, then left overnight in the refrigerator. Long orange needles of anhydrodesdimethylaminochlortetracycline separated in an analytically pure state. This material decomposed without liquefaction at about 240 C. For analysis it was dried at 100 C. in vacuo. Anal. calcd. for CoHI6NO, C1 : C, 57. 49 ; H, 3. 85 ; N, 3. 35 ; Cl, 8. 49 ; m. w. 418. Found : C, 57. 13 ; H, 4. 04 ; N, 3. 17 ; Cl, 8. 70, m. w. (titration) 421. Anhydrodesdimethylaminochlortetracycline shows-228. 7 (dimethylformamide).

Its ultraviolet absorption spectrum is superimposable upon that of anhydrochlortetracycline. EXAMPLE II. Anhydradesdimep. hylaminooxytetracycline- A solution of 0. 5 g. of desdimethylaminooxy- tetracycline in 10 ml. of methanol and 1 ml. concentrated hydrochloric acid was heated to boiling for one minute. The heavy yellow crystalline precipitate which formed was filtered from the cooled solution, and recrystallized from dioxane-methanol to yield 0.4 g. pure anhydrodesdimethylaminooxytetracycline, m. p. 232-233 (dec.). [a.],,"=+170' (dioxane). Anal. Calcd. for C20HltNO8 : C, 60. 15 ; H, 4. 29 ; N, 3. 51. Found : C, 60. 00 ; H, 4. 47 ; N, 3. 52. The ultraviolet absorption spectrum is substantially identical to that of anhydrooxytetracycline in either acid or alkaline ethanol solution. EXAMPLE III. Anhydrodesdimethylaminodesoxyoxytetracycline-Desdimethylaminodesoxyoxy tetracyc- line (5. 0 g.) was dissolved in methanol (150 ml.). To the stirred solution was slowly added concentrated hydrochloric acid (20 ml.) when the deep yellow solution became orange and turbid. After 45 minutes a dark precipitate had formed. The mixture set overnight at room temperature when it was filtered. A small amount of dark red solid collected on the filter. The filtrate was evaporated to dryness when the residue was a bright deep yellow. It gave an amber-green with methanolic ferric chloride and an intense red with concentrated sulfuric acid. It was crystallized from aqueous ethanol. The ultraviolet absorption spectrum was that of a typical anhydro compound. Ultraviolet absorption (methanol HC1) : peaks at 225, 267, 323, 415 mu. melting point 200-203 with decomposition. EXAMPLE IV. Anhydrodesdirxethylnnainotetracycline-Des- dimethylaminotetracycline was subjected to the identical acid treatment described for dehydration of desdimethylaminooxytetra- cycline (Example II). As in the latter case, the product crystallized directly from the acidmethanol reaction solvent as yellow prismatic needles in approximately 80% yield. This material shows a biological assay of 26 oxytetracycline units per mg. against Klebsiella pneurswaiae. The ultraviolet absorption spec- trum, which is essentially identical with that of anhydrodestimethylaminooxytetracycline shows maxima at 270 mu (log c2. 06) and 25 mol (log ?1.29). EXAMPLE V. Anhydrodiacetyloxytetracycline - Diacetyloxytetracycline (5.0 g.) was

dissolved in chloroform (550 ml.). Hydrogen chloride was passed through the yellow solution for five minutes when it became slowly orange. After standing at room temperature overnight, the solution was evaporated to dryness when the residue was a glassy orange solid which was crystallized as the hydrochloride from 0. 5 normal hydrochloric acid. The product gave a greenish-amber color with methanolic ferric chloride and an intense red color with concentrated sulfuric acid. The ultraviolet absorption spectrum was that of a typical anhydro compound. Analysis showed two acetyl groups present. ~ Ultraviolet absorption (methanol HC) : peaks at 229, 271, 329, 429 m . Infrared absorption: peaks at 3.08, 3.45, 5. 75, 6. 05, 6. 17, 6. 23 mu.. Melting point 189-192 with decomposi- tion. EXAMPLE VI. Anhydromethomycin-In a two liter flask there was placed one liter of reagent grade acetone, 200 g. of anhydrous potassium carbonate, 29 g. of desdimethylaminodesoxy- oxytetracycline and 20 g. of methyl iodide. The mixture was refluxed vigorously for 24 hours, then 70 g. of additional methyl iodide was introduced and-reflux maintained for an additional 48 hours. The potassium salts were filtered off and dissolved in water. The water was extracted with ether, then acidifie with 50% sulfuric acid. Acidification of the aqueous solution of methomycin resulted in the rapid formation of the corresponding anhydro compound. The yellow solid product which separated weighed 17.0 g. It was purified by crystallization from ethanol. Anal. Calc. for CHNO, : C, 63. 47 ; H, 4. 82 ; N, 3. 53. Found : C, 63. 68 ; H, 5. 01 ; N, 3. 78. Melting point 233-234. Neutra1 equivalent 203. Ultraviolet peak EtOH-HCl A226, 268, 300 (shoulder), 327, 412 m ! l. Infrared peau in mineral oil-2. 84, 2. 98, 3. 10, 6. 09, 6. 18, 6. 30, 6. 35, ! EXAMPLE VII. Anhydrodesdimethylaminodesoxyoxytetracycliane-15 grams of Desdimethylaminodesoxy- oxytetracycline was treated with a solution of 15. 2 grams of anhydrous hydrogen chloride in 600 milliliters of pure acetone cooled to -5~ C. and the temperature was allowed to rise to about 5~ C. until a constant value of the optical rotation of-300'was obtained. This takes approximately 9i hours. The solution was observe for its ultraviolet absorption characteristics during the course of the reaction. It was noted that the characteristic absorption spectrum of the anhydro compound gradually appeared. After a few hours the conversion was practically complete.

EXAMPLE VIII. Samples of desdimethylaminooxytetracyc- line, desdimethylaminochlortetracyclins, and desdimethylaminotetracycline were individually treated as described in Example VII above with a solution of anhydrous hydrogen chloride in acetone. After a period of several hours at a temperature of about 5 C. each of the solutions was concentrated under vacuum. When a small volume had been reached the solid acetone derivatives of anhydrodesdimethylamincoxytetracycline, anhydrodesdimethylaminochlortetracycline and anhydrodesdimethylaminotetracycline separated as solid yellow products. These materials were isolated and identifie by their characteristic properties, including ultraviolet absorption spectrum. It was found that by treatment with aqueous acid each of these acetone derivatives was readily converted to the corresponding anhydro compounds, that is anhydrodesdimethylaminooxytetracycline, anhydrodesdimethylaminochlortetracycline, and anhydrodesdimethylaminotetracycline. The identity of these compounds was confirmed by their characteristic properties.

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