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Aldehydes, Ketones and Carboxylic Acids · Question 19

NEET (UG) 2022MCQMedium📈 Topic in 25% papers+4−1
1

Which one of the following is not formed when acetone reacts with 2-pentanone in the presence of dilute NaOH followed by heating?

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

Answer

(2) [figure]

Solution

Acetone CH3COCH3 forms an enolate at CH3; 2-pentanone CH3COCH2CH2CH3 forms enolates at C-1 (CH3) or C-3 (CH2). Aldol addition followed by heating gives α,β-unsaturated ketones.

(1) Acetone enolate + acetone (CH3)2C=CH-CO-CH3 (self condensation) — formed.

(3) Acetone enolate + 2-pentanone CH3CH2CH2-C(CH3)=CH-CO-CH3 — formed.

(4) C-3 enolate of 2-pentanone + acetone (CH3)2C=C(C2H5)-CO-CH3 — formed.

(2) C2H5-CO-C(CH3)=C(C2H5)2 contains an ethyl ketone unit C2H5-CO- and a pentan-3-one-derived =C(C2H5)2 unit; neither acetone nor 2-pentanone can supply these.

Compound (2) is not formed.

Answer: (2)

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2

Which of the following reactions is not an example for nucleophilic addition-elimination reaction?

  1. CH3CHO + NH3 CH3CH=NH + H2O
  2. CH3CHO + NaHSO3 CH3- H | OH |C-SO3Na
  3. CH3CHO + NH2OH CH3CH=N-OH + H2O
  4. CH3CHO + C6H5NHNH2 CH3CH=N-NHC6H5 + H2O
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3

The product formed from the following reaction sequence is [figure]

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

The products A and B in the following reaction sequence are : [figure]

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

The incorrect method to synthesize benzaldehyde is

  1. [figure] , CH3MgBr, followed by H3O+
  2. [figure] , H2, Pd-BaSO4
  3. [figure] , DIBAL-H, followed by H2O
  4. [figure] , CrO2Cl2 in CS2, followed by H3O+
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6

Match List-I with List-II Choose the correct answer from the options given below.

  1. (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i)
  2. (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)
  3. (a)-(iii), (b)-(ii), (c)-(i), (d)-(iv)
  4. (a)-(i), (b)-(iv), (c)-(iii), (d)-(ii)
NEET (UG) 2021
7

The intermediate compound 'X' in the following chemical reaction is : [figure]

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
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8

The product formed in the following chemical reaction is : [figure]

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
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9

Identify compound X in the following sequence of reactions : [figure]

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

Reaction between benzaldehyde and acetophenone in presence of dilute NaOH is known as :

  1. Cannizzaro's reaction
  2. Cross Cannizzaro's reaction
  3. Cross Aldol condensation
  4. Aldol condensation
NEET (UG) 2020
11

The major product of the following reaction is : [figure]

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
NEET (UG) 2019

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