cak – 1 aldehydes and ketones - einstein classeseinsteinclasses.com/aldehydes_ketones.pdf · cak...

CAK – 1

Einstein Classes, Unit No. 102, 103, Vardhman Ring Road Plaza, Vikas Puri Extn., Outer Ring Road

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

ALDEHYDES AND KETONES

C1A Physical Properties :

It has high dipole moment

Boiling point are lower than alcohols due to their inability to form intermolecular H-bonding.

B.Pt. are higher than corresponding alkanes due to dipole-dipole interaction.

Carbonyl group can form H-bond with H2O hence they are soluble in water to varying extent.

C1B Method of Preparation :

1. Oxidation :

(a)

(b)

(c)

This oxidation is called as oppenauer oxidation.

2. Rossenmund Reduction :

3. [LiAlH (O-t-C4H

9)

3 or Lithium tri-t-butoxy Aluminium hydride]

4.

5. Hydrolysis of Gem-Dihalide

(a)

(b)

CAK – 2


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

(c) ArCHOArCHClArCHOH

2heat,Cl

322

6. Hydration of Alkynes : Hydration of alkynes gives ketones (except CH CH which gives CH3CHO)

(a) CHOCHCHCH 3HgSO

H,OH

4

2

(b)33

HgSO

H,OH3 COCHCHCHCCH

4

2

7. Hydroboration Oxidation :

Hydroboration of a non-terminal alkyne followed by oxidation of the intermediate yields a ketonebut terminal alkyne yield aldehyde.

8. Use of Grignard Reagent :

(a) With HCN aldehyde is formed.

(b) With RCN a ketone is formed.

9. With Esters

(a)

(b)

10. Decarboxylation of calcium salts of carboxylic acids :

11. Oxo Process :

2 CH3CH = CH

2 + CO + H

2 CH

3CH

2CH

2CHO +

[COH(CO)4] Cobal + Carbonyl hydride

CAK – 3


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

12. Reduction of acid chloride with organocopper compounds :

13. Friedel-Crafts Acylation :

(a)

(b)

14. From Cadmium and Lithium Salts :

1. 2RMgX + CdCl2 R – Cd – R + MgCl

2 + MgX

2

R – Cd – R + R’COCl RCOR’ + RCdCl

R should be 10 alkyl or aryl (–C6H

5)

15. Ozonylysis of Alkene (Zn/H+) Aldehyde/Ketone

C2 Chemical Properties :

1. Nucleophilic Addition to the Carbon-Oxygen Double bond :

The most characteristic reaction of aldehyde and ketone is nucleophilic addition to thecarbon-oxygen double bond.

General Reaction :

Relative reactivity of Aldehydes versus Ketones :

Aldehydes are more reactive than Ketones. There are two reasons for this, they are as follows :

1. Steric Factor 2. Electronic factor

1. Steric Factor : With one group being the small hydrogen atom, the central carbon of the tetrahedralproduct formed from the aldehyde is less crowded and the product is more stable.

With ketones two alkyl groups at the carbonyl carbon causes greater steric crowding in thetetrahedral product and make it less stable. Therefore small concentration is present at equilibrium.

2. Electronic Factor : Because alkyl group are electron releasing therefore aldehydes are more reactiveon electronic grounds as well. Aldehyde have one electron releasing alkyl group to stablise the partialpositive charge on the carbon atom of the carbonyl group. Whereas ketones have two alkyl groups.

CAK – 4


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

(a) Addition of cyanide :

(b) Addition derivatives of ammonia :

(i)

(ii) HCHO reacts with NH3 differently forming UROTROPINE [hexamethylene tetraamine].

6HCHO + 4NH3 (CH

2)

6N

4 + 4H

2O

H2N – G Product

H2N – OH Hydroxylamine = N – OH oxime

H2N – NH

2Hydrazine = N – NH

2Hydrazone

H2N – NHC

6H

5Phenylhydrazine = N – NHC

6H

5Phenylhydrazone

H2N – NHCOCH

2Semicarbazine = NNHCOCH

2Semicarbazone

(c) Addition of Alcohols : Acetal Formation

(i)

CAK – 5


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

(ii)

Important :

(d) Addition of Grignard reagents :

Formaldehyde with Grignard Reagent gives 10alcohol, all higher aldehydes with grignard reagentgive 20 alcohol and ketones with grignard reagent gives the 30 alcohol.

C3 Other Reactions of Aldehyde and Ketones :

(a) Oxidation :

(i) RCHO or ArCHO

Aldehydes (except) benzaldehyde reduce “Fehling’s Solution” (Cu2+ reduced to Cu+) which is analkaline solution of Cu2+ ion complexed with tetrarate ion.

(ii) Example : Tollen’s Test :

OH2NH4Ag2COOCHOH3)NH(Ag2CHOCH 23

mirrorSilver

3–

SolutionColourless

233

Fehling Solution OH2Cu2COOCHOH3Cu2CHOCH 2.PPtdRe

32

3

Tollen’s test is cheifly given by aldehydes. Tollen’s reagent does not attack carbon-carbon doublebond. Aldehyde also reduce benedict’s solution (Cu2+ complexed with citrate ion) to Cu+

(b) (i) Ketones with strong oxidants and at high temperature undergo cleavage of C-Cbond on either side of carbonyl group.

Carbonyl Group after bond cleavage goes with that alkyl group which is of smallersize.

(ii) Ketones are also oxidised from cleavage of bond by caro’s acid (H2SO

5) or

peroxybenzoic acid (C6H

5CO

3H) to esters. RRCOORRCO

]O[

SOH 52 [Bayer’ss

Villiger Oxidation]

CAK – 6


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

(c) Haloform Test :

(i) Methylketones :

(ii) Hypohalite NaOX (NaOH + X2) cannot only halogenate can also oxidise alcohols

(d) Reduction :

(a) Reduction to alcohol

(e) Reduction to hydrocarbons :

(f) Reductive Amination (Discussed under Amines)

(g) Cannizzaro reaction : In the presence of an concentrated base i.e. alkali, aldehydescontaining no -hydrogens undergo self oxidation and reduction to yield a mixture of analcohol.

(i)

(ii)

CAK – 7


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

(h) Crossed Cannizzaro reaction :

(i) Tischenko Reaction :

All aldehyde in presence of aluminium ethoxide, Al(OC2H5)

3 can be simultaneously oxidised

(to acid) and reduced (to alcohols) to form ester. This is called Tischenko reaction and isthus like cannizaro reaction.

(j) Distinction

Aldehyde and Ketones

S.No. Test RCHO RCOR

1. Schiffs magenta no. reactionreagent colour restored by

RCHO

2. Tollen’s reagent is reduced by RCHO is not reduced

3. Fehling’s solution is reduced by RCHO is not reduced(except C

6H

5CHO) -hydroxy, ketones

reudce Tollen’s reagent and Fehling’ssolution

Practice Problems :

1. Identify (Z) in the reaction series, )Y()X(CHCH HydrolysisHBr22 )Z(

NaOH

)excess(I2

(a) C2H

5I (b) C

2H

5OH (c) CHI

3(d) CH

3CHO

2. A compound (X) of the formula C3H

8O yields a compound C

3H

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. Which statement is incorrect in the case of acetaldehyde and acetone

(a) both react with hydroxylamine

(b) both react with NaHSO3

CAK – 8


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

(c) both react with hydrazine

(d) both reduce ammonical silver nitrate

4. Which of the following undergoes Cannizzaro’s reaction

(a) CH3CHO (b) CH

3CH

2CHO (c) (CH

3)

2CHCHO (d) HCHO

5. Urotropine is formed by the action of ammonia on

(a) acetaldehyde (b) formaldehyde (c) acetone (d) phenol

6. Hydrocarbons are formed when aldehydes and ketones are reacted with amalgamated zinc andconc. HCl. The reaction is called

(a) Cannizzaro’s reaction (b) Clemmensen’s reduction

(c) Rosenmund’s reaction (d) Tischenko reaction

7. When acetaldehyde is treated with aluminium ethoxide, it forms

(a) ethyl acetate (b) ethyl alcohol

(c) acetic acid (d) methyl propionate

8. Chloretone is formed when chloroform reacts with

(a) formaldehyde (b) acetaldehyde (c) acetone (d) benzaldehyde

9. Which of the following reagent reacts differently with HCHO, CH3CHO and CH

3COCH

3

(a) HCN (b) NH2OH (c) C

6H

5NHNH

2(d) NH

3

10. In the following sequence of reactions, the end product is

()B()A(CaC ]O[SOH/HgOH2

422

2

)E()D()C( heat)OH(Ca 2

(a) acetaldehyde (b) formaldehyde (c) acetic acid (d) acetone

11. In the following sequence of reactions, the end product is

()A(CHHC]OH[

MgXCHSOH/Hg

2

3422

)C()B( ]O[

(a) acetaldehyde (b) isopropyl alcohol

(c) acetone (d) ethyl alcohol

12. In the following sequence of reactions, the end product is )B()A(CHOCH OHHCN3

2

(a) CH3COOH (b) CH

3CHOHCOOH

(c) CH3CH

2NH

2(d) CH

3CONH

2

13. A compound, C5H

10O, forms a phenyl hydrazone and gives negative Tollen’s and iodoform tests. The

compound on reduction gives n-pentane. The compound A is

(a) pentanal (b) pentanone-2 (c) pentanone-3 (d) amyl alcohol

14. The product Z in the series is

YXCHCH HydrolysisHBr22 Z

32

2

CONa

)excess(I

(a) C2H

5I (b) C

2H

5OH (c) CHI

3(d) CH

3CHO

15. If formaldehyde and KOH are treated together, we get

(a) methane (b) methanol (c) ethyl acetate (d) acetylene

16. The correct order of reactivity in nucleophilic addition reaction CH3CHO, CH

3COC

2H

5 and

CH3COCH

3 is

(a) CH3CHO > CH

3COCH

3 > CH

3COC

2H

5

(b) C2H

5COCH

3 > CH

3COCH

3 > CH

3CHO

(c) CH3COCH

3 > CH

3CHO > C

2H

5COCH

3

(d) CH3COCH

3 > C

2H

5COCH

3 > CH

3CHO

CAK – 9


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

17. To distinguish between 2-pentanone and 3-pentanone which reagent can be used

(a) NaOH/I2

(b) Tollen’s reagent

(c) K2Cr

2O

7/H+ (d) Zn–Hg, HCl

18. CH3CH = CHCHO is oxidised to CH

3 – CH = CHCOOH, using oxidising agent as

(a) alkaline KMnO4

(b) K2Cr

2O

7/conc. H

2SO

4

(c) ammonical AgNO3

(d) dilute HNO3

19. m-chloro benzaldehyde on reaction with conc. KOH at room temperature gives

(a) potassium m-chloro benzoate and m-hydroxy benzaldehyde

(b) m-chloro benzyl alcohol and m-hydroxy benzaldehyde

(c) m-chloro benzyl alcohol and m-hydroxy benzyl alcohol

(d) m-chloro benzyl alcohol and potassium m-chloro benzoate

20. The reagent which can be used to distinguish acetophenone from benzophenone is :

(a) 2, 4-dinitrophenyl hydrazine (b) benedict reagent

(c) I2 and Na

2CO

3(d) aqueous solution of NaHSO

3

21. Best starting material to synthesize 2-methyl-2-butenoic acid is

(a) (b) CH3CH

2CH

2CHO

(c) (d)

22. X and Y can be distinguished by :

(a) silver-mirror test(b) iodoform test (c) both (d) none

23. Which of the following will give haloform test

(a)3

||O

3 CClCCH (b) ICHCCH 2

OH|

3

(c) ClCHCCH 2

O||

3 (d) all

[Answers : (1) c (2) b (3) d (4) d (5) b (6) b (7) a (8) c (9) d (10) d (11) c (12) b (13) c (14) c (15) b(16) a (17) a (18) a (19) d (20) c (21) c (22) c (23) d]

CAK – 10


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

SINGLE CORRECT CHOICE TYPE

1. Which of the following reagent reacts differentlywith HCHO, CH

3CHO and CH

3COCH

3

(a) HCN (b) NH2OH

(c) C6H

5NHNH

2(d) NH

3

2. In the following sequence of reactions, the endproduct is

)B()A(CHOCHheat

agentgDehydratin

alkalimild

onCondensati3

(a) aldol

(b) crotonaldehyde

(c) paraldehyde

(d) metaldehyde

3. Which of the following reaction is a condensationreaction

(a) HCHO Paraformaldehyde

(b) CH3CHO Paraldehyde

(c) CH3COCH

3 Mesityl oxide

(d) CH2 = CH

2 Polyethylene

4. A compound A has molecular formula C2Cl

3OH. It

reduces Fehling’s solution and on oxidation gives amonocarboxylic acid. A is obtained by the action ofCl

2 on ethyl alcohol. The compound A is

(a) chloroform

(b) chloral

(c) trichloro ethanol

(d) trichloro acetic acid

5. The product Z in the series is

YXCHCH HydrolysisHBr22

Z32

2

CONa

)excess(I

(a) C2H

5I (b) C

2H

5OH

(c) CHI3

(d) CH3CHO

6. Cyanohydrin of which of the following gives lacticacid on hydrolysis

(a) acetone (b) acetaldehyde

(c) propanal (d) HCHO

7. In the reaction CH3CHO + HCN CH

3CHOHCN,

a chiral centre is produced. The product is

(a) meso compound

(b) laevorotatory

(c) dextrorotatory

(d) racemic mixture

8. Formic acid and formaldehyde can be distinguishedby treating with

(a) Benedict’s solution

(b) Tollen’s reagent

(c) Fehling’s solution

(d) NaHCO3

9. 2CH3CHO 352 )HOC(Al

CH3COOCH

2CH

3. This

reaction is called

(a) Cannizzaro’s reaction

(b) Aldol condensation

(c) Claisen’s reaction

(d) Tischenko reaction

10. The reaction involving condensation of acetic an-hydride with an aromatic aldehyde by a carboxy-late ion is an example of

(a) aldol condensation

(b) benzoin condensation

(c) Perkin reaction

(d) Wurtz reaction

11. Benzaldehyde when refluxed with aqueous alcoholicKCN forms

(a) benzoin

(b) benzene

(c) phenyl cyanide

(d) phenyl isocyanide

12. Benzyl alcohol is obtained from benzaldehyde by

(a) Wurtz reaction

(b) Cannizzaro’s reaction

(c) Perkin reaction

(d) Claisen reaction

13. C6H

6 + CO + HCl 3AlCl.Anhyd

(X) + HCl

The compound (X) is

(a) C6H

5CHO (b) C

6H

5COOH

(c) C6H

5CH

2Cl (d) C

6H

5CH

3

14. Which of the following is the weakest acid

(a) benzene sulphonic acid

(b) benzoic acid

(c) benzyl alcohol

(d) phenol

CAK – 11


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

15. In the Cannizzaro’s reaction given below

22OH PhCOOHCHPhCHOPh2

the slowest step is

(a) attack of OH— at the carbonyl group

(b) the transfer of hydride to the carbonylgroup

(c) the abstraction of proton from thecarboxylic acid

(d) the deprotonation of Ph–CH2OH

16. The reagent(s) which can be used to distinguishacetophenone from benzophenone is (are) :

(a) 2, 4-dinitrophenyl hydrazine

(b) benedict reagent

(c) I2 and Na

2CO

3

(d) aqueous solution of NaHSO3

17. m-chloro benzaldehyde on reaction with conc. KOHat room temperature gives

(a) potassium m-chloro benzoate andm-hydroxy benzaldehyde

(b) m-chloro benzyl alcohol andm-hydroxy benzaldehyde

(c) m-chloro benzyl alcohol and m-hydroxybenzyl alcohol

(d) m-chloro benzyl alcohol and potassiumm-chloro benzoate

18. A natural compound (X), C4H

8O

2, reduces Fehling’s

solution, liberates hydrogen when treated withsodium metal and gives a positive iodoform test.The structure of (X) is

(a) CH3CHOHCH

2CHO

(b) HOCH2CH

2CHO

(c) CH3COCH

2CHO

(d) CH3COCH

2CH

2OH

19.

X and Y can be distinguished by :

(a) silver-mirror test(b) iodoform test

(c) both (d) none

20. Which of the following will give haloform test

(a)3

||O

3 CClCCH

(b) ICHCCH 2

OH|

3

(c) ClCHCCH 2

O||

3

(d) all

21. cannizzaro

X and YY(Y is alcohol, D is deuterium)

X and Y will have structure :

(a)

(b)

(c)

(d) none is correct

22. NaOH

AA

A is :

(a)

(b)

(c)

(d) none is correct

CAK – 12


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

23. A carbonyl compound with molecular weight 86,does not reduce Fehling’s solution but formscrystalline bisulphite derivatives and givesiodoform test. The possible compounds can be

(a) 2-pentanone and 3-pentanone

(b) 2-pentanone and 3-methyl-2-butanone

(c) 2-pentanone and pentanal

(d) 3-pentanone and 3-methyl-2-butanone

24. In the Cannizzaro’s reaction given below,

PhCOOOHPhCHCHOPh2 2OH

the slowest step is

(a) the attack of OH— at the carbonyl group

(b) the transfer of hydride to the carbonylgroup

(c) the abstraction of proton from thecarboxylic acid

(d) the deprotonation of Ph–CH2OH

ANSWERS (SINGLE CORRECTCHOICE TYPE)

1. d

2. b

3. c

4. b

5. c

6. b

7. d

8. d

9. d

10. c

11. a

12. b

13. a

14. c

15. b

16. c

17. d

18. a

19. c

20. d

21. a

22. a

23. b

24. b

CAK – 13


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

EXCERCISE BASED ON NEW PATTERN

COMPREHENSION TYPE

Comprehension-1

)OHC(AolCyclohexan 106acetone

CrOH 42

)HC(C)OHC(B 127heat

HA147

OH)2(

MgICH)1(

3

3

)OHC(E)OHC(D 3127OH)2(

OH,OAg)1(2127

HOAc,Zn)2(

O)1(

3

23

1. The structure of compound B formed is

(a) (b)

(c) (d)

2. The D formed in the above sequence is

(a)

(b)

(c)

(d) HOOC(CH2)

4COOH

3. D on treatment with Ag2O, OH– and upon

acidification forms

(a)

(b)

(c)

(d) HOOC(CH2)

4COOH

Comprehension-2

The following reaction sequence shows how thecarbon chain of an aldehyde may be lengthened bytwo carbon atoms.

heat,HA3126

OH)2(

Zn,EtCOBrCH)1()OHC(KEthanal

3

22

)OHC(M)OHC(LOH)2(

HDIBAL)1(2126

Pt,H2106

2

2

butanal

4. Structure of K formed is

(a)

(b)

(c)

(d)

5. Thus L is

(a)

(b)

(c) CH3CH = CHCO

2Et

(d)

6. Thus M is

(a) CH3CH

2CH

2CO

2Et

(b)

(c)

(d) CH3CH

2COOH

Comprehension-3

A

B

H)ii(

NaOH)i( Product(s) ?

7. The missing reagent A is

(a) OsO4, NaHSO

3(b) dilute KMnO

4

(c) any one of these (d) O3/H

2O

2

8. The missing reagent B is

(a) HIO4

(b) NaIO4

(c) any one of these (d) None

CAK – 14


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

9. The product(s) formed is/are

(a) (b)

(c) both of these (d) none

MULTIPLE CORRECT CHOICE TYPE

1. A new carbon-carbon bond formation is possiblein

(a) Cannizoro reaction

(b) Friedal-craft reaction

(c) Clemensen reduction

(d) Reimen-Tiemann reaction

2. Which of the following undergoes AldolCondensation

(a) Acetaldehyde

(b) propionaldehyde

(c) Benzaldehyde

(d) Trideuteroacetaldehyde

3. Which of the following on reduction with LiAlH4

with give ethyl alcohol ?

(a) (CH3CO)

2O (b) CH

3COCl

(c) CH3CO NH

2(d) CH

3COOC

2H

5

4. Acetophenone is obtained when

(a) Benzoylchloride treated with dimethylcadmium

(b) Acetylchloride is treated with dimethylcadmium

(c) Acetyl chloride is treated with benzenein presence of anhydrous AlCl

3

(d) Benzoyl chloride is reduced with H2 in

presence of Lindar’s catalyst

5. Which of the following on oxidation with alk.KMnO

4 followed by acidification with HCl gives

benzoic acid

(a) Methyl benzene (b) Ethyl benzene

(c) O-xylene (d) p-xylene

6. Which of the following statements aboutBenzaldehyde is/are true ?

(a) Reduces Tollen’s reagent

(b) Undergoes Aldol condensation

(c) Undergoes cannizaro’s reaction

(d) Does not form an addition compoundwith NaHSO

3

7. Base-catalysed Aldol condensation occurs with

(a) propionaldehyde

(b) Benzaldehyde

(c) 2-Methyl propionaldehyde

(d) 2, 2-Dimethyl-propionaldehyde

8. On heating which of the following getdecarboxylated ?

(a) Methylmalonic acid

(b) succinic acid

(c) 2, 2-Dimethyl acetoacetic acid

(d) Maliec acid

9. Cannizaro reaction will be given by

(a) (b)

(c) (d) CCl3 CHO

10. Which of the following is/are correct about anacetal ?

(a) it is a condensation product of twomolecules of aldehyde

(b) it is the condensation product of twomolecules of ketones

(c) it is the condensation product of onemolecular of aldehyde two molecules ofAlcohols

(d) it is a diether

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 : H2CO is a planar molecule.

STATEMENT-2 : In H2CO, C is sp2 hybridised

2. STATEMENT-1 : H2 + PhCH

2CH

2COCl

C/Pd

quinolineorS Ph CH

2CH

2CHO

above reaction is correct.

STATEMENT-2 : The reduction stops at thealdehyde stage because the catalyst is poinsonedby adding quinoline.

CAK – 15


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

3. STATEMENT-1 : 42SOH

The above reaction is pinacol-pinacolonerearrangement.

STATEMENT-2 : In Pinacol-pinacolonerearrangement formation of the cyclopbtyl C+ isunlikely because the ring strain decreases.

4. STATEMENT-1 : When C6H

6 react with

CO + HCl in the presence of CuCl/AlCl3, it form

C6H

5CHO.

STATEMENT-2 : The electrophilic aromaticsubstitution take place in above reaction.

5. STATEMENT-1 : Under wollff-kishner reductionRCHO reduce to CH

4.

STATEMENT-2 : Under Clemmenson reductionpHCH

2CHO reduce to pHCH

2CH

3

6. STATEMENT-1 : H2CO is always oxidised in the

crossed cannizzaro reaction.

STATEMENT-2 : H2CO is the most reactive

aldehyde, it exists in aqueous OH– solution mainlyas the conjugate base of its hydrate, H

2C(OH)O–.

7. STATEMENT-1 : PCC oxidises 10 alcohol toaldehyde and 20 alcohol to ketone.

STATEMENT-2 : Cu dehydrates 30 alcohol toalkene.

8. STATEMENT-1 : Aldehydes are more reactivethan carboxyl group.

STATEMENT-2 : Carbonyl compounds cannotform hydrogen bonding with H

2O.

9. STATEMENT-1 : Boiling points of carbonylcompounds are higher than those of alkanes.

STATEMENT-2 : Boiling points of carbonylcompound are higher because of hydrogen-bonding.

10. STATEMENT-1 : The reaction of aldehydes andketones with LiAlH

4 and NaBH

4 is uncleophilic

addition reaction.

STATEMENT-2 : Aldol condensation reaction isnot given by C

6H

5CHO.

(Answers) EXCERCISE BASED ON NEW PATTERN

COMPREHENSION TYPE

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

7. c 8. c 9. c

MULTIPLE CORRECT CHOICE TYPE

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

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

ASSERTION-REASON TYPE

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

7. B 8. C 9. C 10. B

CAK – 16


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

INITIAL STEP EXERCISE

(SUBJECTIVE)

1. Complete the following equations and write downthe names of the products :

(i) = O 4

42

LiAlH.2

SOH/KCN.1 ?

(ii) ?CHCCHCHOH,OH)ii(

THF,BD)i(23

22

3

2. Identify the (A), (B), (C) and (D) in the followingreactions sequence :

(i) (CHOCHCHCH NaBH3

4

)C()B()A(H

KCNHCl

ZnCl2

(ii) ()A(BrCHCHCH 2Br.)alc(KOH223

)D()C()B(2

422

Hg

.)dil(SOH

.)alc(KOH

NaNHbyfollowed

(iii) )B()A(CHOCH PClOAg3

52

)D()C(H/OH

MgBrCHH

BaSO/Pd2

32

4

3. What happens when (Give equation only) Chloralis heated with aqueous sodium hydroxide.

4. How will you differentiate between

(i) Acetaldehyde and Acetone.

5. How would you bring the following conversions :

(a) Acetone from acetaldehyde.

(b) Methanal to ethanal (not more than3 steps)

(c) Acetone from methane.

(d) 2-Butanone from ethyl alcohol.

(e) 3-Hexanone from n-propyl alcohol.

6. Arrange the following :

(i) CH3CHO, CH

3COCH

3, HCHO,

C2H

5COCH

3 in decreasing order of

nucleophilic addition.

(ii) CH3COCH

2CHO,CH

3COCH

3,

CH3CHO, CH

3COCH

2COCH

3 in

increasing order of expected enol content.

7. A ketone (A) which undergoes haloform reactiongives compound (B) on reduction. (B) on heatingwith sulphuric acid gives compound (C), whichforms monozonide (D). (D) on hydrolysis inpresence of zinc dust gives only acetaldehyde.Identify (A), (B) and (C). Write down the reactionsinvolved.

8. Show, by equations, how acetaldehyde may beconverted into :

(i) EtOH; (ii) CH3COCl; (iii) CHI

3; (iv) MeCOEt;

(v) CH3CO

2Et; (vi) CH

3CHOHCO

2H; (vii) EtNH

2;

(viii) CH3CHBrCHBrCO

2H.

9. Convert ClCH2CH

2CHO into HOCH

2CHOHCHO.

10. Compound (A) and (B) on reaction in ethermedium and subsequent acidification andoxidation give 2, 5-dimethyl 3-hexanone. What are(A) and(B) ?

11. Identify (A) to (E) as reactant, reagent, product orname of the reaction in following :

(i) )B(OC)CH(3 )A(23

Aldol condensation

(ii) )D(HCOClCH )C(23

Rosenmund’s reaction

(iii) )F(CHCHCH)E( 323

NHNH

ONaHC

22

52

12. Write the structural formula of the main organicprudent formed when : the compound obtained bythe hydration of ethyne is treated with dilutealkali.

13. How can we convert PhCH = CHCOCH3 to

(a) PhCH = CHCOOH

(b) PhCH = CHCHOHCH3

(c) PhCH2CH

2COCH

3

(d) PhCH = CHCH2CH

3

(e) Ph(CH2)

3CH

3

14. An organic compound (A) contains 40% carbonand 6.7% hydrogen. Its V.D. is 15. On reaction witha conc. solution of KOH, it gives two compounds(B) and (C). When (B) is oxidised, the original com-pound (A) is obtained. (C) give effervecence withNaHCO

3. Write the structures of A, B, C and D and

explain the reactions.

15. An organic compound (A), C4H

9Cl on reacting with

aqueous KOH gives (B) and on reaction alc. KOHgives (C) which is also formed on passing thevapours of (B) over heated copper. The compound

CAK – 17


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

(C) readily decolourizes bromine water. Ozonoly-sis of (C) gives two compounds (D) and (E). Com-pound (D) reacts with NH

2OH to give (F) and the

compound (E) reacts with NaOH to give an alcohol(G) and sod. salt (H) of an acid. (D) can also beprepared from propyne on treatment with water inpresence of Hg++ and H

2SO

4. Identify (A) to (H) with

proper reasoning.

16. How would you convert :

17. An organic compound A, C8H

6, on treatment with

dilute H2SO

4 containing HgSO

4 gives a compound

B which can also be obtained from the reaction ofbenzene with an acid chloride in the presence ofanhydrous AlCl

3. The compound B when treated

with iodine and aq. KOH, yields C and a yellowcompound D. Identify A, B, C and D withjustification. Show how C and D is formed.

18. A certain hydrocarbon A was found to contain85.7% C and 14.3 % H. This compound consumes1 molar equivalent of hydrogen to give a saturatedhydrocarbon B. 1.0 g of hydrocarbon A justdecolourised 38.05 of a 5 percent s o l u t i o n(by weight) of Br

2 in CCl

4. Compound A on

oxidation with concentrated KMnO4 gave

compound C (molecular formulae C4H

8O) and

acetic acid. Compound C could easily be preparedby action of acidic aqueous HgSO

4 on 2-Butyne.

Determine the molecular formula of A and deducethe structure of A, B and C

FINAL STEP EXERCISE

(SUBJECTIVE)

1. How would you bring the following conversions :

(a) Ethanal to 2-hydroxy-3-butenoic acid.

(b) Propanal to

2. Convert : (i) n-butanol into 2-ethylhexan-1-ol;(ii) bromocyclohexane into cyclopentancarboxylicacid.

3. Suggest what compounds the letters stand for inthe following equations :

(i)

BCHCHMeCOMeA)ii(

NaNH)i( 2

(ii)

CEtCOClCHPhCOMe 2NaNH22

(iii)

DEtCOClCHBuOHt

BuOKt22

4. Complete the following equations and give reasonsfor your answer.

(i) ?OHCH)OH(CMe H22

(ii) ?MePh)OH(C)OH(PhMeC H

5. Compound (A), C10

H12

O gives off hydrogen ontreatment with sodium metal and also decolourisesBr

2 in CCl

4 to give (B), C

10H

12OBr

2. (A) on treat-

ment with I2 in NaOH gives iodoform and an acid

(C) after acidification. Give structures of (A) to (C)and also of all the geometrical and optical isomersof (A).

6. A organic compound (A), C9H

12O was subjected in

a series of test in the laboratory. It was found thatthis compound

(i) Rotates the plane of polarised light.

(ii) Evolves hydrogen with sodium

(iii) Reacts with NaOH and I2 to produce a

pale yellow solid compound.

(iv) Does not react with Br2/CCl

4.

(v) Reacts with hot KMnO4 to form

compound (B) C7H

6O

2 which can also be

synthesised by the reaction of benzeneand carbonyl chloride followed byhydrolysis.

(vi) looses optical activity as a result offormation of compound (C) on beingheated with HI and P.

(vii) Reacts with Lucas reagent in about 5 min.Give structures of (A) to (C) with properreasoning and draw fischer projectionsfor (A). Give reactions for the stepswherever possible.

CAK – 18


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

7. A neutral organic compound (A) on analysis gaveC = 52.17%; H = 13.04%. On mild oxidation (A)gave (B) which on treatment with dilute NaOH gaveanother neutral compound (C) with double themolecular mass. Compound (C) readily loseswater on heating to form (D) which on oxidationgave CH

3CH = CHCOOH (crotonic acid). Identify

(A), (B), (C) and (D) and explain the reactions.

8. (a) Identify A, B, in the following set up

OHO BA 3

(b) An alkyne with 5 carbon atoms permolecule when passed through dilutesulphuric acid containing mercuricsulphate gives a compound which formsan oxime, but has no effect on Fehling’ssolution. The compound on oxidationgives dimethyl acetic acid. It reacts withsodamide to forms a hydrocarbon. Whatis the structure of the alkyne ?

9. When 0.0088 g of compound (A) was dissolved in0.50 g. of camphor, the melting point of camphorwas lowered by 80C. Analysis of (A) gave 68.18% Cand 13.16% H. Compound (A) showed thefollowing reactions : (i) It reacted with acetylchloride and evolved hydrogen with sodium, (ii)When reacted with HCl + ZnCl

2, a dense oily layer

separated out immediately. Compound (A) waspassed over Al

2O

3 at 3500C to give compound (B).

(B) on ozonolysis followed by hydrolysis gave twoneutral compounds (C) and (D) which gavepositive tests with carboyl reagents but only (C)gave a positive test with Fehling solution. Identify(A), (B), (C) and (D) with proper reasoning. K

f for

camphor = 40 mol–1 kg–1.

10. Suggest the appropriate structures for the missingcompound. (The number of carbon atoms remainthe same throughout the reactions)

CBA HOHIOKMnO.dil 44

11.

Identify A to G.

12. Wolff-Kishner reduction of the compound showngave compound A. Treatment of compound A withm-chloroperoxy benzoic acid gave B which onreduction with LiAlH

4 gave C. Oxidation of

compound C with chromic acid gave compound D(C

9H

14O). Identify A, B, C and D.

13. An optically active alkyne A contains 89.52% C and10.48 % H. After hydrogenation over a Pd catalystit is converted to 1-Methyl-4-propyl cyclohexane.When compound A reacts with CH

3MgBr no gas

is liberated. Hydrogenation of A over Lindlarcatalyst, followed by ozonylysis and reaction withKMnO

4 gives product B. Product B reacts with

I2/NaOH and gives a yellow precipitate, which is

filtered off. Acidification of the filterate gives anoptically active product C. Give the structures ofA, B and C and account for all observations.

14. Give the structure for compounds A – F :

CBOHC /HA

OH.2

MgICH.1

acetone

CrOH

A126

3

342

FEDOH.2

OH,OAg

COOHCH/Zn.2

O.1

3

2

3

3

15. C6H

12O

6 can be glucose or fructose. To decide

nature, one can carry out following steps :

?OHC HI/POHHCN6126

3

What can be the end product starting with glucoseand fructose ?

cak – 1 aldehydes and ketones - einstein classeseinsteinclasses.com/aldehydes_ketones.pdf · cak...

Documents