Dehydration of alcohols by conc. $\mathrm{H}_{2} \mathrm{SO}_{4}$ takes place according to following steps:…

Dehydration of alcohols by conc. $\mathrm{H}_{2} \mathrm{SO}_{4}$ takes place according to following steps:


The slowest and fastest steps in the above reaction are
  1. step 1 is slowest, while 3 is fastest.
  2. step 2 is slowest, while 3 is fastest.
  3. step 2 is slowest, while 4 is fastest.
  4. all steps proceed at equal rate.

Solution

Step 2 involves the formation of carbonium ion by the loss of weakly basic $\mathrm{H}_{2} \mathrm{O}$ molecule. It is slowest step. Step 4 involves the conversion of an unstable (or intermediate) into a quite stable product, hence it is fastest step.

Asked in: JEE-TOPICTESTS-CHEMISTRY

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