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Haloalkanes and Haloarenes · Question 18

NEET 2017MCQHard📈 Topic in 12% papers+4−1
1

Identify A and predict the type of reaction. [figure]

  1. [figure] and elimination addition reaction
  2. [figure] and cine substitution reaction
  3. [figure] and cine substitution
  4. [figure] and substitution reaction

Answer

(4) [figure] and substitution reaction

Solution

With the strong base NaNH2, the aryl halide reacts through a benzyne intermediate (elimination–addition):

(i) NH2- removes the H ortho to Br and Br- is lost ⇒ 3-methoxybenzyne.

(ii) NH2- adds to the benzyne carbon that gives the carbanion next to -OCH3 (stabilised by its −I effect), i.e. at the meta position; protonation follows.

∴ A = m-methoxyaniline (3-methoxyaniline):

[figure]

Overall, Br is replaced by -NH2 at the same (meta) position ⇒ a substitution reaction.

Answer: (4)

NEET 2017

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2

Consider the reaction, CH3CH2CH2Br + NaCN CH3CH2CH2CN + NaBr The reaction will be the fastest in

  1. ethanol
  2. methanol
  3. N,N-dimethylformamide (DMF)
  4. water
NEET 2016 (Phase 2)
3

Which of the following reaction(s) can be used for the preparation of alkyl halides? (I) CH3CH2OH + HCl Anh. ZnCl2 (II) CH3CH2OH + HCl Anh. ZnCl2 (III) (CH3)3COH + HCl Anh. ZnCl2 (IV) (CH3)2CHOH + HCl Anh. ZnCl2

  1. (I) and (II) only
  2. (IV) only
  3. (III) and (IV) only
  4. (I), (III) and (IV) only
AIPMT 2015
4

In the replacement reaction [figure] The reaction will be most favourable if M happens to be

  1. Na
  2. K
  3. Rb
  4. Li
AIPMT 2012 (Mains)
5

Which of the following compounds undergoes nucleophilic substitution reaction most easily?

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
AIPMT 2011 (Mains)
6

Consider the reactions. (i) (CH3)2CH-CH2Br C2H5OH (CH3)2CH-CH2OC2H5 + HBr (ii) (CH3)2CH-CH2Br C2H5O- (CH3)2CH-CH2OC2H5 + Br- The mechanisms of reactions (i) and (ii) are respectively

  1. SN1 and SN2
  2. SN1 and SN1
  3. SN2 and SN2
  4. SN2 and SN1
AIPMT 2011 (Mains)
7

Which one is a nucleophilic substitution reaction among the following ?

  1. CH3-CH=CH2 + H2O H+ CH3- OH |CH-CH3
  2. RCHO + R'MgX R- OH |CH-R'
  3. CH3-CH2- CH3 |CH-CH2Br + NH3 CH3-CH2- CH3 |CH-CH2NH2
  4. CH3CHO + HCN CH3CH(OH)CN
AIPMT 2011 (Prelims)
8

In the following reaction C6H5CH2Br [2. H3O+]1. Mg, ether X, the product 'X' is

  1. C6H5CH2OCH2C6H5
  2. C6H5CH2OH
  3. C6H5CH3
  4. C6H5CH2CH2C6H5
AIPMT 2010 (Mains)
9

The reaction of toluene with Cl2 in presence of FeCl3 gives X and reaction in presence of light gives Y. Thus, X and Y are

  1. X = Benzal chloride, Y = o-chlorotoluene
  2. X = m-chlorotoluene, Y = p-chlorotoluene
  3. X = o- and p-chlorotoluene, Y = Trichloromethyl benzene
  4. X = Benzyl chloride, Y = m-chlorotoluene
AIPMT 2010 (Prelims)
10

Which one is most reactive towards SN1 reaction?

  1. C6H5CH(C6H5)Br
  2. C6H5CH(CH3)Br
  3. C6H5C(CH3)(C6H5)Br
  4. C6H5CH2Br
AIPMT 2010 (Prelims)
11

The correct order of increasing reactivity of [figure] C–X bond towards nucleophile in the following compounds is

  1. I < II < IV < III
  2. II < III < I < IV
  3. IV < III < I < II
  4. III < II < I < IV
AIPMT 2010 (Prelims)

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