In the given reaction, 3-bromo-2,2-dimethylbutane \(\xrightarrow{\ \mathrm{C_2H_5OH}\ }\) 'A' (major product). Product A is:

(A) 2-Ethoxy-2,3-dimethyl butane

(B) 2-Hydroxy-3,3-dimethyl butane.

(C) 2-Ethoxy-3,3-dimethyl butane

(D) 1-Ethoxy-3,3-dimethyl butane.

JEE Main · 2021 · 20 Jul 2021 · Shift 1 · Haloalkanes and Haloarenes

In the given reaction, 3-bromo-2,2-dimethylbutane

C_{2} H_{5} OH

'A' (major product). Product A is:

(A)2-Ethoxy-2,3-dimethyl butane✓ Correct
(B)2-Hydroxy-3,3-dimethyl butane.
(C)2-Ethoxy-3,3-dimethyl butane
(D)1-Ethoxy-3,3-dimethyl butane.

Answer: (A)

Solution

Ethanol is a weak nucleophile but a good ionising solvent, so the reaction goes through a carbocation. Loss of bromide from

(C H_{3})_{3} C - CHBr - C H_{3}

gives a secondary cation sitting next to a quaternary carbon, and a

1, 2

-methyl shift from that carbon converts it into the much more stable tertiary cation

(C H_{3})_{2} C + - CH (C H_{3})_{2}

. Ethanol adds its oxygen to this tertiary centre and the oxonium ion formed loses a proton to a second molecule of ethanol. The major product is 2-ethoxy-2,3-dimethylbutane.

JEE Main · 2021 · 20 Jul 2021 · Shift 1 · Single correct option

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JEE Main · 2021 · 20 Jul 2021 · Shift 1 · Haloalkanes and Haloarenes

Solution

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