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Aldehydes, Ketones and Carboxylic Acids

AIPMT 2015MCQEasy📈 Topic in 38% papers+4−1
Ques. 1AIPMT 2015

Reaction of a carbonyl compound with one of the following reagents involves nucleophilic addition followed by elimination of water. The reagent is

  1. hydrazine in presence of feebly acidic solution
  2. hydrocyanic acid
  3. sodium hydrogen sulphate
  4. a Grignard reagent.

Answer

(1) hydrazine in presence of feebly acidic solution

Solution

As per NCERT, ammonia derivatives Z-NH2 (hydroxylamine, hydrazine, phenylhydrazine, semicarbazide …) add to the carbonyl group in a weakly acidic medium and the adduct then loses water (addition–elimination):

>C=O + H2N-NH2 >C(OH)-NH-NH2 -H2O >C=N-NH2 (hydrazone)

HCN, NaHSO3 and Grignard reagents give only addition products (cyanohydrin, bisulphite adduct, alcohol after hydrolysis) — no elimination of water.

Answer: (1)

Keep practising — Aldehydes, Ketones and Carboxylic Acids

Ques. 2AIPMT 2015

Which one of the following esters gets hydrolysed most easily under alkaline conditions?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 3AIPMT 2015 (Cancelled)

Treatment of cyclopentanone [figure] with methyl lithium gives which of the following species ?

  1. Cyclopentanonyl radical
  2. Cyclopentanonyl biradical
  3. Cyclopentanonyl anion
  4. Cyclopentanonyl cation
Ques. 4AIPMT 2015 (Cancelled)

An organic compound 'X' having molecular formula C5H10O yields phenylhydrazone and gives negative response to the iodoform test and Tollens' test. It produces n-pentane on reduction. 'X' could be

  1. 3-pentanone
  2. n-amyl alcohol
  3. pentanal
  4. 2-pentanone
Ques. 5AIPMT 2014

Which one is most reactive towards nucleophilic addition reaction?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
Ques. 6NEET 2013

Reaction by which benzaldehyde cannot be prepared

  1. [figure] + CO + HCl in presence of anhydrous AlCl3
  2. [figure] + Zn/Hg and conc. HCl
  3. [figure] + CrO2Cl2 in CS2 followed by H3O+
  4. [figure] + H2 in presence of Pd-BaSO4
Ques. 7NEET 2013 (Karnataka)

In the following reaction: HC CH [Hg2+]H2SO4 'P' Product 'P' will not give

  1. Tollen's reagent test
  2. Brady's reagent test
  3. Victor Meyer test
  4. Iodoform test
Ques. 8AIPMT 2012 (Mains)

Consider the reaction : RCHO + NH2NH2 RCH = N - NH2 What sort of reaction is it?

  1. Electrophilic addition-elimination reaction
  2. Free radical addition-elimination reaction
  3. Electrophilic substitution-elimination reaction
  4. Nucleophilic addition-elimination reaction
Ques. 9AIPMT 2012 (Mains)

Which of the following compounds will give a yellow precipitate with iodine and alkali?

  1. Acetophenone
  2. Methyl acetate
  3. Acetamide
  4. 2-Hydroxypropane
Ques. 10AIPMT 2012 (Mains)

Consider the following reaction [figure] The product A is

  1. C6H5CHO
  2. C6H5OH
  3. C6H5COCH3
  4. C6H5Cl
Ques. 11AIPMT 2012 (Prelims)

In the following sequence of reactions CH3-Br KCNA H3O+B [ether]LiAlH4C the end product (C) is

  1. acetone
  2. methane
  3. acetaldehyde
  4. ethyl alcohol

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