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Aldehydes, Ketones and Carboxylic Acids · Question 40

AIPMT 2015 (Cancelled)MCQMedium📈 Topic in 38% papers+4−1
1

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

Answer

(3) Cyclopentanonyl anion

Solution

Methyl lithium ( CH3 --Li +) behaves like a Grignard reagent: the CH3 part is a strong nucleophile.

It attacks the electrophilic carbonyl carbon and the π electrons of C=O move to oxygen ⇒ a tetrahedral alkoxide ion is formed:

[figure]

∴ The species formed is an anion (alkoxide of cyclopentanone, which on hydrolysis gives 1-methylcyclopentanol).

Answer: (3)

AIPMT 2015 (Cancelled)

Keep practising — Aldehydes, Ketones and Carboxylic Acids

2

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
AIPMT 2015 (Cancelled)
3

Which one is most reactive towards nucleophilic addition reaction?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2014
4

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
NEET 2013
5

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
NEET 2013 (Karnataka)
6

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
AIPMT 2012 (Mains)
7

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

  1. Acetophenone
  2. Methyl acetate
  3. Acetamide
  4. 2-Hydroxypropane
AIPMT 2012 (Mains)
8

Consider the following reaction [figure] The product A is

  1. C6H5CHO
  2. C6H5OH
  3. C6H5COCH3
  4. C6H5Cl
AIPMT 2012 (Mains)
9

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
AIPMT 2012 (Prelims)
10

CH3CHO and C6H5CH2CHO can be distinguished chemically by

  1. Benedict's test
  2. Iodoform test
  3. Tollens' reagent test
  4. Fehling's solution test
AIPMT 2012 (Prelims)
11

The correct order of decreasing acid strength of trichloroacetic acid (A), trifluoroacetic acid (B), acetic acid (C) and formic acid (D) is

  1. B > A > D > C
  2. B > D > C > A
  3. A > B > C > D
  4. A > C > B > D
AIPMT 2012 (Prelims)

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