Chapter 11: Q22P (page 566)

Predict the products of the sulfuric acid-catalyzed dehydration of the following alcohols. When more than one product is expected, label the major and minor products.
(a) 2-methylbutan-2-ol (b) pentan-1-ol (c) pentan-2-ol
(d) 1-isopropylcyclohexanol (e) 2-methylcyclohexanol

Short Answer

Expert verified

(a)

(b)

(c)

(d)

(e)

Step by step solution

Step 1: Dehydration of Alcohols

Removal of a water molecule from the alcohol compound is known as dehydration of alcohols with the help of reagent concentration H₂SO₄ followed by heating, which will take out the water molecule from the given alcohol chemically, leadingto the formation of alkene product.

product of sulfuric acid-catalyzed dehydration of given alcohols

Dehydration requires an acidic catalyst to protonate the hydroxy group of the alcohol and convert it to a good leaving group. Loss of water, followed by loss of a proton, gives the alkene.

(a) When the sulfuric acid-catalyzed dehydration reaction on 2-methyl butane-2-ol, two products are formed: 2-methyl but-2-ene (major product) and 2-methyl but-1-ene (minor product).

(b) When sulfuric acid-catalyzed dehydration reaction is done onpentan-1-ol, two products are formed: (E)-pent-2-ene (major product) and pent-1-ene (minor product).

(c) When sulfuric acid-catalyzed dehydration reaction is done onpentan-2-ol, two products are formed: (E)-pent-2-ene (major product) and pent-1-ene (minor product).

(d) When sulfuric acid-catalyzed dehydration reaction is done on 1-isopropylcyclohexanol, two products are formed: propan-2-ylidenecyclohexane (major product) and 1-isopropylcyclohex-1-ene(minor product).

(e) When sulfuric acid-catalyzed dehydration reaction is done on 2-methylcyclohexanol, two products are formed: 1-methylcyclohex-1-ene (major product), 3- methylcyclohex-1-ene (minor product), and some amount of trace product forme is methylenecyclohexane