ALCOHOLS, ETHERS AND PHENOLS - Einstein Classeseinsteinclasses.com/Al_Ether_Phenol.pdf · ALCOHOLS,...

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ALCOHOLS, ETHERS AND PHENOLS

Alcohols :

C1A Physical Properties :

The lower alcohols are completely soluble in water but as the number of carbon atoms increases,solubility decreases. This solubility in water is due to intermolecular H-bonding between water andalcohols molecules due to their polar character.

Increase in C-chain increases organic part hence solubility in water decreases.

Isomeric 10, 20, 30 alcohols have solubility in order : 10 > 20 > 30.

C1B Method of preparation of Alcohols :

(i) Hydration of Alkenes :

42SOHdil

Intermediate is carbonium ion that can change to more stable carbanion ion by hydrideshift, alkyl or phenyl shift.

(ii) Hydrolysis of Alkyl Halides :

R – X + aq. NaOH (or H2O) R – OH + NaX (or HX)

Reaction can be 21 NNSorS .

(iii) Reduction of Carbonyl Compounds (including acid derivative) :

(a) OHRCHRCHO 2NaBHorLiAlH 44

10

(b) 44 NaBHorLiAlH

(c) Acid, acid halide, ester and anhydride are reduced to 10 alcohol.

(iv) Hydroboration and oxidation :

3223OH,OH

3223THFinBH

23 )OH(BOHCHCHCHB)CHCHCH(CHCHCH 223

The hydroboronation-oxidation (HBO) process gives product corresponding toanti-Markownikoff addition of H

2O to the carbon-carbon double bond.

(v) Oxymercuration-Demercuration :

OH

)OAc(Hg

2

2 4NaBH

The alcohol obtained corresponds to Markownikov’s addition of water to an Alkene.

(vi) (a) Through Grignard Reagent :

Addition of Grignard Reagent on carbonyl compounds followed by hydrolysisyields alcohols nature of which depends upon types of carbonyl compounds used.

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OH3 + H

2O

R1, R

2 can be H, alkyl or aryl but R

3 is not H.

(b) Grignard reagent with epoxide and after hydrolysis gives 10 alcohol for e.g.,

OH2

Practice Problems :

1. Propene, CH3 – CH = CH

2 can be converted into 1-propanol, Which of the reagent among the

following is ideal to affect the conversion :

(a) alkaline KMnO4

(b) B2H

6 and alkaline H

2O

2

(c) O3/Zn (d) OsO

4/CH

2Cl

2

2. Glycol may be obtained :

(a) by the oxidation of ethylene with cold, dilute, alkaline permanganate solution

(b) by the hydrolysis of ethylene bromide under reflux with aqueous sodium carbonatesolution

(c) by the hydrolysis of ethylene chlorohydrin on boiling with aqueous sodium bicarbonate

(d) by any of the above methods

3. Which of the following are the starting materials for the Grignard’s synthesis of tert. butyl alcohol

(a) CH3MgI + CH

3COCH

3(b) CH

3MgI + CH

3CHOHCH

3

(c) CH3CH

2MgBr + CH

3COCH

3(d) CH

3CH

2MgBr + CH

3CHO

[Answers : (1) b (2) d (3) a]

C2 Chemical Properties :

(i) Dehydration of Alcohol :

42SOH.conc

Alcohols leading to conjugated alkenes are more easily dehydrated then those of alcoholsleading to non-conjugated alkenes.

Dehydration of alcohol is in the order 30 > 20 > 10 as intermediate is carbocation.

(ii) Reaction with Halogen Acids :

R – OH + HX RX + H2O

Intermediate is carbonium ion. The order of reactivity of HX : HI > HBr > HCl for a givenalcohol.

(iii) Reaction with Phosphorous Halides and Thionyl Chloride :

3R – OH + PX3 3RX + H

3PO

3

(X = Br, I)

R – OH + SOCl2 RCl + SO

2 + HCl

(iv) Acidic Character of Alcohol :

RO – H + Na RO–Na+ + ½ H2

alkoxide

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The order of acidic character of alcohol with metal is :

CH3OH > 10 > 20 > 30.

The relative acidities is as follows :

RCOOH > C6H

5OH > H

2O > ROH > CH CH > NH

3 > RH

(v) Ester Formation (alcohol can act as a nucleophile also).

Thus reactivity of alcohols for given acid is in order :

CH3OH > 10 > 20 > 30

and those of acids for given alcohol is in order :

HCOOH > CH3COOH > RCH

2COOH > R

2CHCOOH > R

3CCOOH

(vi) Oxidation of Alcohol :

1. Using Cu

(a) 2Aldehyde

3C300

Cu

123 HCHOCHOHCHCH

00

(b) C300

Cu

0

(c) C300

Cu

0

2. Oxidation using KMnO4/K

2Cr

2O

7

(a) RCOOHOHRCHH)ii(

KMnO)i(2

4

(b)

(c) 72234 OCrKoracid,aceticglacialinCrO,KMnO

3. Other reagents used for oxidation :

(a) PCC (pyridinium chlorochromate) to oxidise 10 alcohols to aldehydes.

(b) MnO2 selectively oxidises the OH group of allylic and benylic 10 and 20

alcohols to give aldehydes and ketones respectively.

C3 Test to distinguish 10, 20 and 30 Acohols :

(a) Lucas Reagent (anhydrous ZnCl2/conc. HCl)

(b) Oxidation

(c) Victor Meyer Test

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Practice Problems :

1. Identify (Z) in the following reactions series :

)Y()X(EthanolKOH.AlcPBr3 )Z(

heat,OH

.temproom,SOH

2

42

(a) CH2 = CH

2(b) CH

3CH

2OH (c) CH

3CH

2OSO

3H (d) C

2H

5OC

2H

5

2. An organic compound gives hydrogen on reacting with sodium metal. It also gives iodoform test andforms an aldehyde of molecular formula C

2H

4O on oxidation with acidified dichromate. The

compound is :

(a) CH3OH (b) CH

3COOH (c) CH

3CHO (d) C

2H

5OH

3. The order of reactivity of the following alcohols,

towards conc. HCl is

(a) I > II > III > IV (b) I > III > II > IV

(c) IV > III > II > I (d) IV > III > I > II

[Answers : (1) b (2) d (3) c]

C4 Ethers

Nomenclature of Ethers :

Cyclic ethers can be named in severay ways :

In another system, a cyclic three membered ether is named as oxirane and a four membered ether iscalled oxetane.

C5 Methods of Preparation of Ether :

(a) Williamson Synthesis :

Example :

(i)

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(ii)

Discussion : Phenol in Williomson’s synthesis :

Because phenols are stronger acids than alcohols they can react with NaOH to change into sodiumphenoxide ion. But alcohols can be converted into sodium alkoxide ion by reaction with sodiummetal only.

[Alkyl halide used here can not be aryl halide as it does not undergo nucleophilic substitution easily]

R – X can be X = –Cl, –Br, I, – OSO3CH

3 etc.

(b) Ethers by Intermolecular Dehydration of Alcohols :

Alcohols can dehydrate to form alkenes.

10 Alcohols can also dehydrate to form ethers.

The formation of ether takes places by 2NS mechanism mainly, with one molecule acting as the

nucleophile and with another protonated molecules of the alcohol acting as the substrate.

Finally this method is not useful for the preparation of ether with 30 alcohol because they formalkene too easily. This method is not useful for the praparation of unsymmetrical ethers fromprimary alcohols because the reaction leads to a mixture of products.

(c) Ethers may be prepared by the addition of alcohols to alkenes in the presence of acid e.g.

Practice Problems :

1. Which route provides a better synthesis of ether :

(a) I (b) II (c) equal (d) none

[Answers : (1) b]

C6 Reactions of Ethers :

(a) Ethers are comparitavely unreactive compounds. The ether linkage are quite stabletowards bases, oxidizing agent, reducing agents. Ether can undergo just one kind ofreaction, cleavage by acids :

XRRXOHRRXHXRORHX

Reactivity of HX : HI > HBr > HCl

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Cleavage takes place only under quite vigourous conditions : concentrated acids (usually HI or HBr)and high temperature.

Oxygen of the ether is basic, like the oxygen of alcohol. The initial reaction between an ether and anacid is undoubtedly formation of the protonated ether.

Cleavage then involves the nucleophilic attack by halide ion on this protonated ether, withdisplacement of the weakly basic alcohol molecule.

As we might expect primary alkyl group tend to undergo 2NS and 30 tend to undergo 1N

S .

(b) Acid Hydrolysis : OHHC2OHHCOHC 5235252 .

(c) Acid Hydrolysis of Epoxide : OH3

(d) Formation of Halohydrin : HX

Practice Problems :

1. Ethoxy ethane does not react with

(a) HI (b) conc. H2SO

4(c) PCl

5(d) Na

2. An ether, (A) having molecular formula, C6H

14O, when treated with excess of HI produced two alkyl

iodides which on hydrolysis yield compounds (B) and (C). Oxidation of (B) gives an acid (D), whereasoxidation of (C) results in the formation of a mixed ketone, (E). Thus structures of (A) is

(a) (b) CH3CH

2CH

2CH

2OCH

2CH

3

(c) (d)

[Answers : (1) d (2) c]

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PHENOLS

C7A Structure and Nomenclature of Phenols :

Compounds that have a hydroxyl group directly attached to benzene ring are called phenols. Thusphenol is specific name of hydroxy benzene

Compounds that have a hydroxyl group attached to a polycyclic benenoid ring are chemicallysimilar to phenols, but they are called napthols and phenanthrols, e.g.

C7B Physical Properties of Phenols : The presence of hydroxy groups in the molecules of phenols meansthat phenols are like alcohols in being able to form strong intermolecular hydrogen bonds.

This hydrogen bonding causes phenols to be associated and therefore to have higher boiling pointsthan hydrocarbons of the same molecular weight.

C8A Synthesis of Phenols :

Laboratory Synthesis : The most important laboratory synthesis of phenols is by hydrolysis ofarenediazonium salts.

This method is highly versatile and the conditions required for the diazotisation step and thehydrolysis step are mild.

1. General Reaction :

Specific Example :

Industrial Synthesis :

2. Hydrolysis of Cholorobenzene (Dow Process) :

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(The mechanism for the reaction probably involves benzyne intermediate)

3. Alkali Fusion of Sodium benzene sulfonate : Sodium benzene sulfonate is melted (fused) with so-dium hydroxide at 3500C to produce sodium phenoxide acidification then yields phenol.

4. From Cumene Hydroperoxide :

I

II This cumene is oxidized to cumene hydrolperoxide

Finally, when treated with 10% sulfuric acid, cumene hydroperoxide undergoes a hydrolyticrearrangement that yields phenol and acetone.

C8B Chemical Properties of Phenol :

1. Reaction of Phenol as Acid : Strength of phenols as acids :

Although phenols are structurally similar to alcohols, they are much stronger acids. The pKa valuesof most alcohols are of the order of 18. However the pKa values of phenols are smaller than 11.

Let us compare two superficially similar compounds cyclohexanol ane phenol.

Although phenol is weak acid when compared with carboxylic acid such as acetic acid (pKa = 4.75)

phenol is much stronger than cyclohexanol by a factor of 8.

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Phenols are more acidic than cyclohexanol because of following reasons :

Phenoxide ion is more resonance stabilized than phenol. Resonance structures of phenoxid ion donot involve charge separation. No resonance structure can be written for cyclohexanol and itsanion of course. The benzene ring of phenol acts as if it were as electron withdrawing group whenwe compare it with cyclohexanol. That causes –OH oxygen to be more positive.

Reason : Carbon atom that bears hydroxyl group in phenol is sp2 hybridized, whereas incyclohexanol sp3 bybridised. Greater the S– characted more electronegative the carbon. Thuscarbon of benzene is more electronegative than cyclohexanol.

Because phenols are more acidic than water, the following reaction goes almost completion.

The reaction between cyclohexanol and NaOH does not occur to significant extent as H2O is stron-

ger acid than 1-wexanol.

Acidity order of Phenols :

(a) (b)

(c) (d)

(e)

Distinguishing and separating phenols from alcohols and carboxylic acids :

1. Phenols dissolve in aqueous sodium hyroxide whereas most alcohols with six carbon atoms ormore do not. Thus we can distinguish them.

2. Alcohols with five carbon atoms are more or less soluble in NaOH but do not form appreciableamount of sodium alkoxide.

3. Most phenols are not solible in aqueous sodium bicarbonate, but carboxylic acids are soluble.

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C9 Other reactions of the O – H Group of Phenols :

1. Phenols react with carboxylic acid anhydrides and acid chlorides to form esters.

Thest reactions are similar to alcoholic as we have already discussed in alcohols.

2. Phenols in the Williamson Synthesis :

Because phenols are more acidic than alcohols they can be converted to sodium phenoxide throughthe use of sodium hydroxide (rather than use of sodium metal, the reagent that convert alcohols toalkoxide ion).

(a) General Reaction : NaXArORaNArOArOH]I,Br,ClX[

XRNaOH

(b) Cleavage of Alkyl-Aryl Ether :

RX.rxnnoOHHCROHCHX

56heat

HX.conc56

3. Reactions of the Benzene ring of Phenol :

(a) Bromination : The hydroxyl group is a powerful activating group and an ortho-paradirector in electrophilic substitution. Phenol itself react with Br

2 in aqueous solution to

yield 2, 4, 6-tribromophenol. Note that a Lewis acid is not required for the bromination ofthis highly activated ring.

(b) Monobromination of phenol can be achieved by carrying out the reaction in carbondisulfide (CS

2) at low temperature. Conditions that reduce the electrophilic activity of

bromine. The major product is the para isomer.

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4. (a) Nitration : Phenol react with dilute nitric acid to yield a mixture o- and p-nitrophenol

Although the yield is relatively low (because of oxidation of ring). The ortho and para isomers can beseparated by steam distillation. o-Nitrophenol is more volatile isomer because its intramolecularhydrogen bonding. p-Nitrophenol is less volatile because intermolecular H-bonding causingassociation among molecules. Thus o-nitrophenol passes over steam and p-Nitrophenol remain inthe distillation flask.

(b)

5. Sulfonation : Phenol reacts with concentrated sulfuric acid to yield mainly o-sulphonated product ifthe reaction is carried out at 250C and mainly the para substituted product if the reaction is at 1000C.

6. Kolbe’s Reaction : The phenoxide ion is even more suceptible to electrophilic aromatic substitution,then phenol itself.

High reactivity of phenoxide ion is used in a reaction called as kolbe reaction. In kolbe reactioncarbon dioxide act as the electrophile.

Reaction of salicylic acid with acetic anyhydride yields widely used pain reliver aspirin.

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7. The Clasien rearrangement :

Clasien rearrangement can also take place when allyl vinyl ether are present

8. Diel Alder reaction is also pericyclic reaction :

9. Quinones : Oxidation of hydroquinone gives quinone

10. Reimer-Tiemann Reaction :

11. Fries rearrangement :

Rearrangement involves RCO+, which then attacks the ring.

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Practice Problems :

1. When phenol is distilled with zinc dust, the main product is

(a) biphenyl (b) benzene

(c) benzaldehyde (d) phenolphtalein

2. When sodium benzene sulphonate is fused with sodium hydroxide (solid), the product formed is

(a) benzene (b) phenol

(c) benzene triphenol (d) none of these

3. Which of the following acids is strongest

(a) C6H

5SO

3H (b) CH

3COOH (c) C

6H

5COOH (d) (COOH)

2

4. Phenol is less acidic then

(a) p-nitrophenol (b) ethanol

(c) cresol (d) benzyl alcohol

5. Cumene 2

2

O)i(

H,OH)ii( (X) and (Y)

(X) and (Y) respectively are

(a) toluene, propene (b) toluene, propylchloride

(c) phenol, acetone (d) phenol, acetaldehyde

6. In the following compounds

the order of acidity is

(a) III > IV > I > II (b) I > IV > III > II

(c) II > I > III > IV (d) IV > III > I > II

7. When phenol reacts with benzene diazonium chloride, the product obtained as

(a) phenyl hydrazine (b) p-amino azobenzene

(c) phenol hydroxylamine (d) p-hydroxy azobenzene

8. )B()A(PhenolHNO.Conc

60at

SOH.Conc

Zinc

ondistillati

3

042 )C()

Zn

NaOH . In the above reaction, compounds (A),

(B) and (C) are

(a) benzene, nitrobenzene and aniline

(b) benzene, dinitrobenzene and m-nitroaniline

(c) toluene, nitrobenzene and m-toluidine

(d) benzene, nitrobenzene and hydrazobenzene

[Answers : (1) b (2) b (3) a (4) a (5) c (6) d (7) d (8) d]

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SINGLE CORRECT CHOICE TYPE

1. Identify (Z) in the reaction series,

)Y()X(CHCHHydrolysisHBr

22

)Z(NaOH

)excess(I 2

(a) C2H

5I (b) C

2H

5OH

(c) CHI3

(d) CH3CHO

2. A compound (X) of the formula C3H

8O yields a

compound C3H

6O on oxidation. To which of the

following class of compounds could (X) belong

(a) aldehyde

(b) secondard alcohol

(c) alkene

(d) tert. alcohol

3. Identify (Z) in the series,

)Y()X(OHHCBr

C170

SOH.Conc73

2

0

42

)Z(KOH.Alc

ofExcess

(a)

(b)

(c) CH3 – C CH

(d)

4. How many isomers of C5H

11OH will be primary

alcohols :

(a) 5 (b) 4

(c) 3 (d) 2

5. An alcohol on oxidation is found to give CH3COOH

and CH3CH

2COOH. The structure of the alcohol is

(a) CH3CH

2CH

2OH

(b) CH3CH

2CH(OH)CH

3

(c) CH3CH(OH)CH

2CH

2CH

3

(d) (CH3)

2C(OH)CH

2CH

3

6.OHCH

NaBH

3

4B A4LiAlH A and B

are :

(a) in both cases

(b) in both cases

(c)

(d) formation of A and B is not possible

7. Out of butane, butanol-1, butanal and butanone,the decreasing order of their boiling point is

(a) butane > butanol > butanal > butanone

(b) butanol > butane > butanal > butanone

(c) butanone > butanal > butanol > butane

(d) butanol > butanal > butanone > butane

8. + CO2

HCl

P

K390X ; The

product X in the reaction is

(a)

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(b)

(c)

(d)

9. In the reaction

)C()B()A(OHHCHydrolysisKCNPI

523

The product (C) is

(a) acetic acid (b) formic acid

(c) oxalic acid (d) propionic acid

10. The ether — O — CH2 —

when treated with conc. HI produces

:

(a)

(b) —CH2OH

(c) —I

(d) —OH

11. Artificial oil of bitter almonds or oil of Mirabane isthe name given to

(a) chlorobenzene (b) benzaldehyde

(c) aniline (d) nitrobenzene

12. Which does not have a carboxyl group

(a) picric acid (b) ethanoic acid

(c) aspirin (d) benzoic acid

13. Phenols do not react with

(a) sodium bicarbonate

(b) sodium hydroxide

(c) potassium hydroxide

(d) ferric chloride

14. 356.)aq(NaOH

ClOCCH56 OOCCHHCOHHC 3

The above reaction is an example of

(a) acetylation

(b) benzoylation

(c) Schotten-Baumann reaction

(d) Reimer-Tiemann reaction

15. Phenol on standing in air develops a red colour dueto formation of

(a) cyclohexane (b) resorcinol

(c) phenoquinone (d) quinol

16. Phenol

H)ii(

NaOH/CHCl)i( 3 Salicyladehyde

This reaction is known as

(a) Gattermann aldehyde synthesis

(b) Duff reaction

(c) Perkin reaction

(d) Reimer-Tiemann reaction

17. Phenol on treatment with dil HNO3 gives

(a) picric acid

(b) o- and p-nitro phenols

(c) o- and m-nitro phenols

(d) p- and m- nitro phenols

18. CH3CH = CH

2

4

22

NaBD

OH/OH product X

X is :

(a)

(b)

(c)

(d) none is correct

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19. Which route provides a better synthesis of ether :

(a) I (b) II

(c) equal (d) none

20. Consider reduction of 2-butanone

Abutanone2BOH

NaBD

OD

NaBD

2

4

2

4

A, B and C are :

(a) in all cases

(b) ,

,

(c) ,

,

(d) in all cases

21. Hydrolysis of the following gave :

OH3 CH

3CHO + X

X is :

(a)

(b)

(c)

(d) none is correct

22. Compound (A), C4H

10O, is found to be soluble in

sulphuric acid. (A) does not react with sodium orpotassium permanganate. When (A) is heated withexcess of HI, it is converted into a single alkyl ha-lide. The (A) is

(a) CH3OCH

2CH

2CH

3

(b) CH3CH

2OCH

2CH

3

(c)

(d)

23. The product (D) in the following sequence of reac-tion is :

()B()A(HC Na)aq(NaOHHBr42

)D()C( ICH3

(a) butane

(b) ethane

(c) propane

(d) ethyl methyl ether

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24. The major product obtained when 3-phenyl-1,2-propane-diol is heated with H

2SO

4 is

(a) C6H

5 – CH

2 – CO – CH

3

(b) C6H

5 – CH

2 – CH

2 – CHO

(c) C6H

5 – CH

2 – CH = CH

2

(d)

25. When phenol is reacted with CHCl3 and NaOH fol-

lowed by acidification, salicylaldehyde is obtained.Which of the followed species are involved in theabove mentioned reaction as intermediates :

(a)

(b)

(c)

(d)

26. The reaction of CH3CH = CH — —OH

with HBr gives :

(a) CH3CHBrCH

2 — —OH

(b) CH3CH

2CHBr— —OH

(c) CH3CHBrCH

2— —Br

(d) CH3CH

2CHBr— —Br

ANSWERS (SINGLE CORRECTCHOICE TYPE)

11. d

12. a

13. a

14. a

15. c

16. d

17. b

18. b

19. b

20. b

1. c

2. b

3. c

4. b

5. c

6. c

7. d

8. d

9. d

10. d

21. c

22. b

23. d

24. d

25. a

26. b

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EXCERCISE BASED ON NEW PATTERN

COMPREHENSION TYPE

Comprehension-1

Oxiranes are synthesized by treating an alkene withan organic peroxy acid. This process is known asepoxidation. The highly strained three-memberedring in epoxide makes it much more reactivetowards nucleophilic substitution than other ethers.

1. The most commonly used peroxy acid is

(a)

(b)

(c)

(d)

2. The base-catalyzed ring opening of the epoxide isrepresented as follows

+ CH3CH

2O–

OHCHCH 23 P or/

and Q

where P is and Q is

which of the following product(s) is/are obtained ?

(a) P only

(b) Q only

(c) Equal mixture of P and Q

(d) Unequal mixture of P and Q

3. The acid-catalyzed ring opening of the expoxide isrepresented as follows

+ CH3OH P or/and Q

where P is and Q is

Which of the following product(s) is/are obtained ?

(a) P only

(b) Q only



Comprehension-2

Oxiranes are synthesized by treating an alkene withan organic peroxy acid. This process is known asepoxidation. The highly strained three-memberedring in epoxide makes it much more reactivetowards nucleophilic substitution than other ethers.

4. In the reaction

P or/and Q

where P is (cis-2,3-dimethyoxirane)

and Q is . The

product(s) obtained is/are

(a) P only

(b) Q only



5. The reaction of C6H

5MgBr with the oxirane

may be represented as

C6H

5MgBr +

H

EtOH P or/and Q

where P is and Q is

Which of the following product(s) is/are obtained ?

(a) P only

(b) Q only



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6. The acid-catalyzed hydrolysis of an epoxide gives

(a) an alcohol (b) a glycol

(c) an aldehyde (d) a ketone

Comprehension-3

Given are the two reactions

(I) PHCl.conc

(II) (CH3)

3C – CH

2OH Q

HCl.conc

7. The reactions (I) and (II), respectively, proceed via

(a)1NS and

1NS mechanisms

(b)1NS and

2NS mechanisms

(c)2NS and

1NS mechanisms

(d)2NS and

2NS mechanisms

8. The products P and Q, respectively, are

(a) and

(CH3)

3C – CH

2 – Cl

(b) and

(CH3)

3C – CH

2 – Cl

(c) and

(d) and

9. The reactions I and II, respectively, follow

(a) first-order and first-order kinetics

(b) first-order and second-order kinetics

(c) second-order and first-order kinetics

(d) second-order and second-order kinetics

Comprehsnion-4

Given are the two reactions

(I) n-C4H

9OH + HBr C

4H

9Br + H

2O

(II) (CH3)

3COH + HBr (CH

3)

2Br + H

2O

10. The reactions I and II, respectively, proceed via

(a)1NS and

1NS mechanisms

(b)1NS and

2NS mechanisms

(c)2NS and

1NS mechanisms

(d)2NS and

2NS mechanisms

11. The reactions I and II, respectively, follow

(a) first-order and first-order rate laws

(b) first-order and second-order rate laws

(c) second-order and first-order rate laws

(d) second-order and second-order rate laws

MATRIX-MATCH TYPE

Matching-1

Column - A Column - B

(A) H

232 OHCHCHCH

(p) 3|

3 HCHCCH

OH

(B)OH)ii(

MgIHC)i(2

2

52OCH (q) CH3CH

2CH

2OH

(C)OH)ii(

MgICH)i(3

2

3CHOCH (r)

HOCH2CHOHCH

3

(D)

4KMnO/OH.dil32 CHCHCH

(s) CH3COOH

Matching-2

Column - A Column - B

(A)

H.3CO.2

OEt,Mg.1|

|3

2

2

3CH

3CH

BrCCH

(p)

(CH3)

3CCH

2OH

(B)

OH.3

OH,OH.2

CN.1|

|3

3

2

3CH

3CH

BrCCH (q)

(CH3)

3CCOOH

CAEP – 20


New Delhi – 110 018, Ph. : 9312629035, 8527112111

(C)

H.2

OH,KMnO.12

|

|3

4

3CH

3CH

OHCHCCH

(r)

(CH3)

3CCH

2COOH

(D)

H.2

OH,KMnO.1|

|3

4

3CH

3CH

CHOCCH

(s)

3

||

33 CHCC)CH(

O

MULTIPLE CORRECT CHOICE TYPE

1. Ethyl bromide can be converted into ethyl alcoholby

(a) heating with moist silver oxide

(b) heating with dry silver oxide

(c) heating with alc KOH

(d) heating with aqous KOH

2. Which of the following yield carboxylic acid as theproduct an oxidation with acidified K

2Cr

2O

7 ?

(a) 1-Butanol (b) 1-Propanol

(c) 2-Propanol (d) 2-Butanol

3. Which of the following reagents/conditions canconvert 2-propanol to acetone ?

(a) LiAlH4

(b) Cu/573 K

(c) K2Cr

2O

7/H+ (d) H

2/Pd

4. Select wrong statements

(a) phenol reacts with Na2CO

3 and liberates

CO2 gas

(b) phenols turn blue litmus to red

(c) reactivity of methanol with sodium metalis more than that of isopropyl alcohol

(d) methanol gives iodoform test

5. Select correct statements

(a) sodium ethoxide is prepared by reactionof ethanol with aqous sodium hydroxide

(b) Picric acid dissolves in NaHCO3 solution

(c) Phenol is a weaker acid than carbonicacid

(d) Dynamite contains T.N.T.

6. Which of the following reactions are wrong

(a) CH2OHCH

2OH

2ZnCl.anhyd

(b) CH2OHCH

2OH

k773 CH3CHO

(c) HOCH2CH

2OH

.distil

SOH.Conc 42

(d) HOCH2CH

2OH

.distil

POH.Conc 43

7. Which gives turbidity with HBr

(a) (b)

(c) (d)

8. Select correct statements

(a) like, alcohols, phenols also easilyprotonated

(b) phenol has smaller dipole moment thanmethanol

(c) Bioling point of ethylene glycol is morethan glycerol

(d) Glycerol reacts with oxalic acid at 503kto give allyl alcohol

9. Ethanol and ethylene glycol can be distinguishedby which of the following tests ?

(a) Lucas test

(b) Iodoform test

(c) Periodic test

(d) Victor-Meyer test

10. Alcohols may act as

(a) Oxidising agent

(b) Reducing agent

(c) Lewis base

(d) Bronsted acid

CAEP – 21


New Delhi – 110 018, Ph. : 9312629035, 8527112111

Assertion-Reason Type

Each question contains STATEMENT-1 (Assertion)and STATEMENT-2 (Reason). Each question has4 choices (A), (B), (C) and (D) out of which ONLYONE is correct.

(A) Statement-1 is True, Statement-2 is True;Statement-2 is a correct explanationfor Statement-1

(B) Statement-1 is True, Statement-2 is True;Statement-2 is NOT a correctexplanation for Statement-1

(C) Statement-1 is True, Statement-2 is False

(D) Statement-1 is False, Statement-2 is True

1. STATEMENT-1 : We can not dry ethanol byanhydrous CaCl

2

STATEMENT-2 : Ethanol form calcium salt(C

2H

5O)

2Ca.

2. STATEMENT-1 : Acid catalysed dehydration oft-butanol is faster than n-butanol.

STATEMENT-2 : The order of stability ofcarbocation is 30 > 20 > 10.

3. STATEMENT-1 : Phenol is more reactive thenbenzene towards electrophillic substitutionreactions.

STATEMENT-2 : In case of phenol theintermediate carbocation is more resonancestabalised.

4. STATEMENT-1 : Methanol is stronger acid thanwater.

STATEMENT-2 : Among mono-hydric aliphaticalcohols methanol is strongest acid.

5. STATEMENT-1 : During acid catalysedesterification oxygen atom of alcohol is present inester molecule.

STATEMENT-2 : Esterification is a reversiblereaction.

6. STATEMENT-1 : Alkenes can be change intoalcohols by oxymercuration-demercurationreaction.

STATEMENT-2 : In this reaction addition occursaccording to Markovnikov’s rule.

7. STATEMENT-1 : Acidic strength ofp-Niprophenol is more than O-Nitrophenol.

STATEMENT-2 : The effect of negative I-effectweakens steadily with increasing distance fromthe substitument.

8. STATEMENT-1 : m-Methoxyphenol is moreacidic than phenol.

STATEMENT-2 : There is a negative I-effect of–OCH

3 group.

(Answers) EXCERCISE BASED ON NEW PATTERN

COMPREHENSION TYPE

1. d 2. a 3. b 4. a 5. a 6. b

7. a 8. c 9. a 10. c 11. c

MATRIX-MATCH TYPE

1. [A-p; B-q; C-p; D-r] 2. [A-q; B-q; C-r; D-q]

MULTIPLE CORRECT CHOICE TYPE

1. a, d 2. a, b 3. b, c 4. a, d 5. b, c 6. a, b

7. a, b, c 8. b, d 9. b, c 10. c, d

ASSERTION-REASON TYPE

1. C 2. B 3. A 4. D 5. B 6. B

7. B 8. A

CAEP – 22


New Delhi – 110 018, Ph. : 9312629035, 8527112111

INITIAL STEP EXERCISE

(SUBJECTIVE)

1. Convert ethanol into (i) n-propanol; (ii) n-butanol.

2. Arrange EtOH, CF3CH

2OH, and CCl

3CH

2OH in

order of increasing strength as acids and give yourreasons.

3. Convert propene into (i) n-PrOH; (ii) iso PrOH.

4. Complete the following equation :

5. Convert (i) n – C4H

9OH into MeC CMe;

(ii) n-PrOH into cis-hex-2-ene.

6. A concentrated aqueous solution of HBr reacts withEtOH to give EtBr, but a concentrated aqueoussolution of NaBr does not. Explain.

7. Complete the following equations :

(i) n-C3H

7CO

2H ?

n-C4H

9OH

(ii) Me2CO + EtMgI

H? ?

(iii) EtCOEt + MeMgI OH2? ?

(iv)

8. 3, 3-Dimethyl-butan-2-ol loses a molecule of waterin the presence of conc. H

2SO

4 to give tetramethyl

ethylene as a major product. Suggest a suitablemechanism.


(i)

)A(OHCHCHCH 5 .)Alc(KOHPBr223

)D()C()B( 3NHHBr

(ii) )B()A(OHCHCH MgI/P23

2

)C(HCHO)i(

H/OH)ii( 2

(iii)

)B(HC)A(OHC 342

heat

HNO106

heat

SOH126

)C()A)(C(OHC3HNO

heat4106

(iv)

)A(ClCHCHCHHC AlCl2266

3

)C(HC)B( 109

HF

heatOH,OH)ii(

THF/BH)i(

22

3

(v)

10. Outline a synthesis of each alcohol from theindicated starting materials :

(a) n-Butyl alcohol from acetylene.

(b) Allyl alcohol from propene.

(c) Glycerol from acetone or isopropylalcohol or propene.

11. How will you obtain :

(a) Propanol-1 from propanol-2 (three steps.)

(b) Ethanol from methanol (three steps)

(c) Vinyl acetate from ethyl alcohol.

(d) Ethanol from acetylene.

12. Arrange the following in order of their increasingbasicity :

H2O, OH—, CH

3OH, CH

3O—

13. Give reasons for the following :

(i) Acid catalysed dehydration of t-butanolis faster than that of n-butanol.

(ii) When t-butanol and n-butanol areseparately treated with a few drops ofdilute KMnO

4, in one case only, the

purple colour disappears and a brownprecipitate is formed. Which of the twoalcohols gives the above reaction andwhat is the brown precipitate ?

14. Write out the structures of all the possible isomericdiols derived from the butanes, and indicate whichcan be oxidised with periodic acid.

15. Arrange the following in order of increasing b.p.,and give your reasons. (CH

2OH)

2, (CH

2OMe)

2,

HOCH2CH

2OMe.

CAEP – 23


New Delhi – 110 018, Ph. : 9312629035, 8527112111

16. Convert :

17. A compound (X) containing C, H and O isunreactive towards sodium. It does not add upbromine. It does also not react with Schiff’s reagent.On refluxing with excess of HI, (X) gives only (Y).(Y) on hydrolysis gives (Z) which can be convertedto (Y) by the action of P and I

2. Compound (Z) on

oxidation gives an acid of equivalent mass 60. Whatare (X), (Y) and (Z) ?

18. Account for the following :

(i) Which of the following is the correctmethod for synthesising methyltert-butyl ether and why.

(a) (CH3)

3C – Br + NaOMe

(b) CH3Br + NaOBu

(ii) 2, 2-Dimethyl oxirane can be cleaved byacid (H+). Write methanism.

19. How would you bring the following conversions :

(i) Ethyl iodide to diethyl ether.

(ii) Methyl iodide to methyl ethyl ether.

20. Compound (A), C4H

10O, is found to be soluble in

sulphuric acid. (A) does not react with sodium orpotassium permanganate. When (A) is heated withexcess of HI, it is converted into a single alkylhalide. What is (A) ?

21. Which of the two reactions would you use toprepare Me

3COMe, and why ?

(i) Me3CBr + MeO—K+ ;

(ii) Me3CO—K+ + MeBr


(i) ?MeOEt HI

(ii) ?OEt Na2

(iii)

??CHCMepressure

COHMe

pressure

OHSOH22

3242

23. The reaction between HI and C2H

4 in EtOH gives

predominantly EtI, whereas the reaction with HClunder the same conditions gives predominantlyEt

2O. Explain.

24. Outline the reaction sequence for the conversion ofmethanol to ethanol (the number of steps shouldnot be more than three).

25. Convert : (i) n-C4H

9OH into MeC CMe; (ii)

n-PrOH into cis-hex-2-ene.

26.

27. An optically active alcohol A (C6H

10O) absorbs two

moles of hydrogen per mole of A upon catalytichydrogenation and gives a product B. Thecompound B is resistant to oxidation by CrO

3 and

does not show any optical activity. Deduce thestructures of A and B.

28. When t-butanol and n-butanol are separatelytreated with a few drops of dilute KMnO

4, in one

case only, the purple colour disappears and brownppt. is formed. Which of the two alcohols gives theabove reaction and what is the brown ppt ?

29. Why does ethylene oxide react readily withnucleophiles such as ammonia, whereas THF isinert to nucleophilic attack by ammonia ?

30. Show the steps by which the following alkyne canbe converted into seven membered ring.

.

FINAL STEP EXERCISE

(SUBJECTIVE)

1.

A, on ozonolysis, gives nonane-2, 8-dione. What isA and how is it formed ?

2. What are A to E in the following reactions ?

3. What reagent could you use for the followingconversions ?

(i) MeCO(CH2)

2CO

2Et

MeCHOH(CH2)

2CO

2Et

CAEP – 24


New Delhi – 110 018, Ph. : 9312629035, 8527112111

and (C). Oxidation of (B) gives an acid (D), whereasoxidation of (C) results in the formation of a mixedketone, (E). Give structures of (A) to (E).

9. A neutral compound (A) having C, H and O, onrefluxing with HI yields methyl iodide and an alkyliodide (B), which contains 74.6 per cent iodine. (B)when treated with moist Ag

2O produces a product

which undergoes the haloform reaction.Characterize (A), what would have been producedif (B) were treated with dry Ag

2O ?

10. An organic compound (A) C4H

9Cl on reacting with

aqueous KOH gives (B) and on reaction withalcoholic KOH gives (C) which is also formed onpassing the vapours of (B) over heated copper. Thecompound (C) readily decolourises bromine water.Ozonolysis of (C) gives two compounds (D) and (E).Compound (D) reacts with NH

2OH to give (F) and

the compound (E) reacts with NaOH to give aalcohol (G) and sodium salt (H) of an acid. (D) canalso be prepared from propyne on treatment withwater in presence of Hg2+ and H

2SO

4. Identify (A)

to (H) with proper reasoning.

11. Compound (A) gives Lucas test in 5 minutes. When6 gm of (A) is treated with sodium metal, 1120 mLof hydrogen is evolved at STP. Assuming (A) tocontain one atom of oxygen per molecule, write thestructural formulae of (A). Compound (A) whentreated with PBr

3, gives compound (B) which when

treated with benzene in presence of anhydrousaluminium chloride gives compound (C). Writedown the structural formulae of (B) and (C) andalso write the reactions involved.

12. How would you convert :

Toluene to p-nitro benzyl ethyl ether.

13. 0.037 g of an alcohol, ROH, was added to CH3MgI

and the gas evolved measured 11.2 cm3 at S.T.P.What is the mol. wt. of ROH ? On dehydration,ROH gives an alkene which on ozonolysis givesacetone as one of the products. ROH on oxidationeasily gives an acid containing the same number ofcarbon atoms. Give structures of ROH and the acidwith proper reasoning.

14. Give products of each reaction.

(a) 3

42

CrO

SOH.aq

(b) 4

323

NaBH)2(

OHCH/)OOCCF(Hg)1(

(c) OHCH

SOH

3

42

(d)

(ii) HO2C(CH

2)

4COCl

HO2C(CH

2)

4CH

2OH

(iii) O2N(CH

2)

2CN O

2N(CH

2)

2CH

2NH

2

(iv) O2N(CH

2)

2CH = CH

2 H

2N(CH

2)

2

CH = CH2

(v) O2N(CH

2)

2CH = CH

2 O

2N(CH

2)

3CH

3

(vi) Me2CHCOCl Me

2CHCHO

(vii) O2N(CH

2)

3CHO O

2N(CH

2)

3CH

2OH

4. An alcohol (A) when heated with concentratedH

2SO

4 gives an alkene (B). When (B) is bubbled

through bromine water and the product obtainedis dehydrohalogenated with excess of sodamide, anew compound (C) is obtained. The compound (C)gives (D) when treated with dilute H

2SO

4 in

presence of HgSO4. (D) can also be obtained either

by oxidising (A) with KMnO4 or from acetic acid

through its calcium salt. Identify (A), (B), (C) and(D).

5. Compound ‘X’ (molecular formula C5H

8O) does not

react appreciably with Lucas reagent at roomtemperature but gives a white precipitate withammonical silver nitrate solution. With excess ofMeMgBr, 0.42 g of ‘X’ gives 224 mL of CH

4 at STP.

Treatment of ‘X’ with H2 in presence of Pt catalyst

followed by boiling with HI, gives n-pentane.Suggest structure for ‘X’ and write the equationsinvolved.


(i)

(ii)


(i)

(ii) ?H)ii(

HHCO)i( 3

(iii)

?CHCH)CH(CHCH62

22

HB)i(

OH;OH)ii(2222

8. An ether, (A) having molecular formula, C6H

14O,

when treated with excess of HI produced two alkyliodides which on hydrolysis yield compounds (B)

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