T-butyl bromide (2-bromo-2-methylpropane) can be prepared by simply taking t-butyl alcohol and shaking it with an aqueous solution of hbr at room temperature. the reaction is much faster than with n-butyl alcohol and is essentially 100% complete within a few minutes. give a mechanism for this reaction. what is this type of reaction called

This is an example of (substitution nucleophilic bimolecular) reaction.

Explanation:

Conversion of t-butyl alcohol to t-butyl bromide proceeds through (substitution nucleophilic bimolecular)mechanism.

In the first step, -OH group in t-butyl alcohol gets protonated.

In the second step, stable tertiary carbocation (t-butyl cation) is produced by removal of .

In the third step, bromide ion attacks to t-butyl cation and produces t-butyl bromide.

Removal of from n-butyl alcohol will produce an unstable primary carbocation (n-butyl cation). Hence, to produce this unstable carboction, large amount of activation energy is required. Therefore, n-butyl alcohol gives much slower reaction with HBr.

Reaction mechanism has been shown below.

"standard molar enthalpy:

h2o ( liquid water ) : - 285.8 kj/mole

h2o ( water vapor ) : - 241.8 kj / mole.

δhrxn = - 241. 8 - ( - 285.8 )= -241.8 + 285.8 = 44.0

answer: 44.0 kj"