What is the main difference between a primary, secondary, and tertiary alcohol?

The main difference between primary, secondary, and tertiary alcohols lies in the number of alkyl groups attached to the carbon atom that is bearing the hydroxyl (-OH) functional group. In a primary alcohol, the carbon with the -OH group is attached to only one other carbon atom, making it relatively less sterically hindered. In contrast, in secondary alcohols, the carbon with the -OH group is bonded to two other carbon atoms, leading to an increase in steric hindrance. Tertiary alcohols have three alkyl groups attached to the carbon with the -OH, resulting in even greater steric hindrance.

This classification is important because it influences the physical and chemical properties of the alcohols, including their reactivity in various chemical reactions. For instance, tertiary alcohols often undergo dehydration reactions more readily than primary alcohols due to the greater stability of the resulting carbocation intermediate.

Understanding this distinction helps chemists predict the behavior of alcohols in reactions and is fundamental in organic chemistry.