Question

Compare the acidic character of Primary, Secondary and Tertiary alcohol.

Hint:

Acidity is inversely proportional to the +I effect of the attached groups. More alkyl groups = Less acidic.

Answer 1

1. The acidity of alcohols depends on the stability of the alkoxide ion (R-O$^-$) formed after releasing a proton.
2. Alkyl groups are electron-releasing (+I effect). They increase electron density on the oxygen atom, destabilizing the negative charge on the alkoxide ion.
3. Primary alcohols ($1^\circ$): Have one alkyl group. Least +I effect. Alkoxide is most stable. Strongest acid.
4. Secondary alcohols ($2^\circ$): Have two alkyl groups. Moderate +I effect.
5. Tertiary alcohols ($3^\circ$): Have three alkyl groups. Maximum +I effect. Alkoxide is least stable. Weakest acid.
Order of Acidity: $1^\circ>2^\circ>3^\circ$.