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Aldehydes, Ketones and Carboxylic Acids · Question 68

AIPMT 2006MCQMedium📈 Topic in 38% papers+4−1
1

A carbonyl compound reacts with hydrogen cyanide to form cyanohydrin which on hydrolysis forms a racemic mixture of α-hydroxy acid. The carbonyl compound is

  1. formaldehyde
  2. acetaldehyde
  3. acetone
  4. diethyl ketone

Answer

(2) acetaldehyde

Solution

R-CO-R' + HCN R-C(OH)(CN)-R' H3O+ R-C(OH)(COOH)-R'

The new carbon is chiral only when R and R′ are different and neither is H twice.

Formaldehyde (H, H), acetone (CH3, CH3) and diethyl ketone (C2H5, C2H5) give achiral products.

Acetaldehyde: CH3CHO + HCN CH3-CH(OH)-CN H3O+ CH3- *CH(OH)-COOH

∵ The planar C=O group is attacked by CN- equally from both faces, both enantiomers of lactic acid (2-hydroxypropanoic acid) form in equal amounts, i.e. a racemic mixture.

Answer: (2)

AIPMT 2006

Keep practising — Aldehydes, Ketones and Carboxylic Acids

2

Nucleophilic addition reaction will be most favoured in

  1. CH3CHO
  2. CH3-CH2-CH2- O \|C-CH3
  3. (CH3)2C=O
  4. CH3CH2CHO
AIPMT 2006
3

Self condensation of two moles of ethyl acetate in presence of sodium ethoxide yields

  1. ethyl propionate
  2. ethyl butyrate
  3. acetoacetic ester
  4. methyl acetoacetate
AIPMT 2006
4

In a set of reactions acetic acid yielded a product D. CH3COOH SOCl2 A [anhy. AlCl3]benzene B HCN C HOH D The structure of D would be

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2005
5

When m-chlorobenzaldehyde is treated with 50% KOH solution, the product(s) obtained is (are)

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2003
6

A and B in the following reactions are : [figure]

  1. [figure]
  2. [figure]
  3. A = RR'CHCN, B = NaOH
  4. [figure]
AIPMT 2003
7

[figure] In the above reaction product P is

  1. [figure]
  2. [figure]
  3. [figure]
  4. C6H5- O \|C-C6H5
AIPMT 2002
8

In the following reaction product P is R- O \|C-Cl [Pd-BaSO4]H2 P

  1. RCH2OH
  2. RCOOH
  3. RCHO
  4. RCH3
AIPMT 2002
9

[figure] Product 'P' in the above reaction is

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2002
10

First product of the reaction between RCHO and NH2NH2 is

  1. RCH=NNH2
  2. RCH=NH
  3. RCH2NH2
  4. RCON3
AIPMT 2000
11

Benzoic acid may be converted into ethyl benzoate by reaction with :

  1. ethyl alcohol
  2. ethyl alcohol and dry HCl
  3. ethyl chloride
  4. sodium ethoxide.
AIPMT 2000

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