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Aldehydes, Ketones and Carboxylic Acids · Question 63

AIPMT 2008MCQMedium📈 Topic in 25% papers+4−1
1

Acetophenone when reacted with a base, C2H5ONa, yields a stable compound which has the structure

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]

Answer

(3) [figure]

Solution

In the presence of the base C2H5ONa, acetophenone (which has α-hydrogens) undergoes aldol condensation with itself.

Step 1: the base removes an α-hydrogen and forms the carbanion (enolate):

C6H5- O \|C-CH3 C2H5O- C6H5- O \|C- CH2

Step 2: the carbanion adds to the carbonyl group of a second acetophenone molecule and gives the β-hydroxy ketone (aldol):

C6H5- CH3 | OH |C-CH2- O \|C-C6H5

Step 3: the aldol loses water and gives the conjugated α,β-unsaturated ketone (dypnone), which is stable:

C6H5- CH3 |C=CH- O \|C-C6H5

The stable compound is 1,3-diphenylbut-2-en-1-one, structure (3).

Answer: (3)

AIPMT 2008

Keep practising — Aldehydes, Ketones and Carboxylic Acids

2

Reduction of aldehydes and ketones into hydrocarbons using zinc amalgam and conc. HCl is called

  1. Cope reduction
  2. Dow reduction
  3. Wolff-Kishner reduction
  4. Clemmensen reduction
AIPMT 2007
3

The product formed in Aldol condensation is

  1. a beta-hydroxy aldehyde or a beta-hydroxy ketone
  2. an alpha-hydroxy aldehyde or ketone
  3. an alpha, beta unsaturated ester
  4. a beta-hydroxy acid.
AIPMT 2007
4

Which one of the following on treatment with 50% aqueous sodium hydroxide yields the corresponding alcohol and acid?

  1. C6H5CHO
  2. CH3CH2CH2CHO
  3. CH3- O \|C-CH3
  4. C6H5CH2CHO
AIPMT 2007
5

Which of the following represents the correct order of the acidity in the given compounds ?

  1. FCH2COOH > CH3COOH > BrCH2COOH > ClCH2COOH
  2. BrCH2COOH > ClCH2COOH > FCH2COOH > CH3COOH
  3. FCH2COOH > ClCH2COOH > BrCH2COOH > CH3COOH
  4. CH3COOH > BrCH2COOH > ClCH2COOH > FCH2COOH
AIPMT 2007
6

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
AIPMT 2006
7

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
8

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
9

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
10

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
11

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

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

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