91Ó°ÊÓ

The Grignard reaction with aldehyde and ketones gives a different degree of alcohol.Formaldehyde reaction with Grignard reagent always gives primary alcohols. Secondary and tertiary alcohols are formed by the Grignard reaction of aldehyde and ketones or esters.

(a) The compound 2-Pentanol is a secondary alcohol, and we know secondary alcohols are formed by the reaction of aldehyde and Grignard reagent. Thus, we can use the following aldehydes and Grignard reagents to synthesize 2-pentanol (secondary alcohol).

Synthesis of 2-Pentanol

(b) The compound 1-Butanol is a primary alcohol, and we know that primary alcohols are formed by the reaction of formaldehyde with the Grignard reagent. Thus, we can use formaldehyde (HCHO) and ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{MgBr}$(Grignard reagent) to synthesize 1-butanol (primary alcohol).

Synthesis of 1-Butanol

(c) The compound 1-Phenylcyclohexanol is tertiary alcohol, and we know tertiary alcohols are formed by the reaction of ketone or ester with the Grignard reagent. Thus, we can use cyclohexanone (ketone) and ${\text{C}}_6{\text{H}}_5\text{MgBr}$(Grignard reagent) to synthesize 1-Phenylcyclohexanol (tertiary alcohol).

Synthesis of 1-Phenylcyclohexanol

(d) The compound Diphenylmethanol is a secondary alcohol, and we know secondary alcohols are formed by the reaction of an aldehyde with the Grignard reagent. Thus, we can use benzaldehyde(aldehyde) and ${\text{C}}_6{\text{H}}_5\text{MgBr}$(Grignard reagent) to synthesize Diphenylmethanol (secondary alcohol).

Synthesis of Diphenylmethanol