Solubility order

Question

Arrange the following alcohols in decreasing order of their solubility in water

1. n-Butylalcohol

2. sec-Butyl alcohol

3. tert-Butyl alcohol

Answer 1

1. n-Butylalcohol = CH₃CH₂CH₂CH₂OH = 1° alcohol (primary alcohol)

2. sec-Butyl alcohol = CH₃CH(OH)CH₂CH₃ = 2° alcohol (secondary alcohol)

3. tert-Butyl alcohol = (CH₃)₃COH = 3° alcohol (tertiary alcohol)

The more exposed the hydroxyl group is to other hydroxyl groups, the more it can participate in hydrogen bonding and increase its boiling point. The boiling points go as 1°>2°>3°.