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Aldehydes, Ketones and Carboxylic Acids · Question 43

NEET 2013MCQEasy📈 Topic in 50% papers+4−1
1

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

Answer

(2) [figure] + Zn/Hg and conc. HCl

Solution

(1) Gattermann–Koch reaction: benzene + CO + HCl (anhydrous AlCl3/CuCl) ⇒ benzaldehyde.

(2) Zn/Hg and conc. HCl is the Clemmensen reagent; it reduces a >C=O group of aldehydes and ketones to >CH2 and does not convert benzoic acid into benzaldehyde.

(3) Etard reaction: toluene + CrO2Cl2 in CS2, then H3O+ ⇒ benzaldehyde.

(4) Rosenmund reduction: benzoyl chloride + H2 / Pd–BaSO4 ⇒ benzaldehyde.

∴ Benzaldehyde cannot be prepared by reaction (2).

Answer: (2)

NEET 2013

Keep practising — Aldehydes, Ketones and Carboxylic Acids

2

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)
3

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)
4

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)
5

Consider the following reaction [figure] The product A is

  1. C6H5CHO
  2. C6H5OH
  3. C6H5COCH3
  4. C6H5Cl
AIPMT 2012 (Mains)
6

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)
7

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)
8

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)
9

Predict the products in the given reaction. [figure]

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2012 (Prelims)
10

Acetone is treated with excess of ethanol in the presence of hydrochloric acid. The product obtained is

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2012 (Prelims)
11

The order of reactivity of phenyl magnesium bromide (PhMgBr) with the following compounds: [figure]

  1. III > II > I
  2. II > I > III
  3. I > III > II
  4. I > II > III
AIPMT 2011 (Mains)

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