Question

What carbonyl compounds would you reduce to prepare the followingalcohols? List all possibilities.

(a)

(b)

(c)

Short answer

(a)

(b)

(c)

Step-by-step solution

Carbonyl compounds needed to prepare the alcohol

Aldehydes are reduced to primary alcohols by${\mathbf{NaBH}}_{\mathbf{4}}$ in either water or alcohol. Aldehydes, acids and esters are reduced to primary alcohols by ${\mathbf{LiAIH}}_{\mathbf{4}}$in ether solution.

Preparation of the given alcohols using carbonyl compounds

(a)Primary alcohols can be preprared from the reduction of aldehydes, esters or carboxylic acids.

The compound 2,2-dimethylhexanal reacts with ${\mathrm{NaBH}}_4$or localid="1656435101517" ${\mathrm{LiAIH}}_{4_{}}$and ${\mathrm{H}}_3{\mathrm{O}}^{+}$to form 2,2-Dimethyl-1-hexanol. The reaction can be given as:

First method of preparation of compound (a)

The compound, Methyl-2,2-dimethylhexanoate reacts with ${\mathrm{NaBH}}_4$or ${\mathrm{LiAIH}}_4$and ${\mathrm{H}}_3{\mathrm{O}}^{+}$to form 2,2-Dimethyl-1-hexanol. The reaction can be given as:

Second method of preparation of compound (a)

2,2-Dimethyl-1-hexanol is obtained from the reduction reaction of 2,2-dimethylhexanoic acid. The reaction can be given as:

Third method of preparation of compound (a)

(b)Secondary alcohols can be prepared by reduction of ketones. The compound, 3,3-dimethyl-2-butanone reacts with ${\mathrm{NaBH}}_4$or${\mathrm{LiAIH}}_4$ and ${\mathrm{H}}_3{\mathrm{O}}^{+}$to form 3,3-dimethyl-2-butanone. The reaction can be given as:

Method of preparation of compound (b)

(c)The compound 1-cyclohexyl-1-propanol reacts with ${\mathrm{NaBH}}_4$or ${\mathrm{LiAIH}}_4$ and H₃O⁺to form 1-cyclohexyl-1-propanone. The reaction can be given as:

Reaction to prepare compound (c)