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Aldehydes, Ketones and Carboxylic Acids

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

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)

Keep practising — Aldehydes, Ketones and Carboxylic Acids

Ques. 2AIPMT 2007

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
Ques. 3AIPMT 2007

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.
Ques. 4AIPMT 2007

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
Ques. 5AIPMT 2007

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
Ques. 6AIPMT 2006

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
Ques. 7AIPMT 2006

Nucleophilic addition reaction will be most favoured in

  1. CH3CHO
  2. CH3-CH2-CH2- O \|C-CH3
  3. (CH3)2C=O
  4. CH3CH2CHO
Ques. 8AIPMT 2006

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
Ques. 9AIPMT 2005

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]
Ques. 10AIPMT 2003

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

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 11AIPMT 2003

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

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

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