Question

What alcohols would give the following products on oxidation?

(a)

(b)

(c)

Short answer

a.

b.

c.

Step-by-step solution

Oxidation of alcohol

The oxidation of alcohol gives carbonyl-containing compounds like aldehyde, ketone, and carboxylic acid.From primary (${\text{1}}^{\text{o}}$) alcohol, aldehyde or carboxylic acid is formed. From secondary (${\text{2}}^{\text{o}}$) alcohol, a ketone is formed. But oxidation of tertiary alcohols does not occur because they do not react much with oxidizing agents.

The alcohol needed to produce the product (a) 

a.

The given product is a ketone, and the alcohol needed for oxidation is secondary. We know that secondary alcohols yield ketones. Here, the reagent used for oxidation is ${\mathrm{CrO}}_{\mathrm{3}}/{\mathrm{H}}_{\mathrm{3}}{\mathrm{O}}^{\mathrm{+}}$.

Oxidation of alcohol

The alcohol needed to produce the product (b) 

b.

The given product is an aldehyde, and the alcohol needed for oxidation is a primary alcohol. We know that primary alcohol on oxidation using Periodinane/ ${\text{CH}}_{\text{2}}{\text{Cl}}_{\text{2}}$gives an aldehyde.

Oxidation of alcohol

The alcohol needed to produce the product (c) 

c.

The given product is a cyclopentanone (ketone), and the alcohol needed for oxidation is cyclopentanol (secondary alcohol). So, when cyclopentanol is treated with ${\text{CrO}}_{\text{3}}{\text{/H}}_{\text{3}}{\text{O}}^{\text{+}}$, the product formed is cyclopentanone because secondary alcohols yield ketones.

Oxidation of alcohol