Question

Why dry hcl is used in nucleophilic addition reaction of alcohol?

Answer 1

Answer:

Dry HCL protonates oxygen of aldehyde or ketone. This positively charged oxygen makes the carbon of carbonyl group highly electron deficient. This will make a nucleophile (like methanol,ethanol,ethane diol,etc.) to attack on carbonyl carbon.

So it is necessary to use dry HCL instead of aqueous HCL.