# What is the difference between acetal and ketal ?

Nov 12, 2015

These names are derived from the compounds you might expect: aldehydes and ketones---two closely-related functional groups.

where ${\text{R}}_{i}$ is just an $\text{R}$ group differentiated by the subscript number.

For example, the ketal formation mechanism works like this (after the initial acid catalysis):

1. After protonation of the carbonyl, the alcohol is a good enough nucleophile in context.
2. Proton transfer Pt1.
3. Proton transfer Pt2.
4. Tetrahedral collapse.
5. With a positively-charged carbonyl, the alcohol is a good enough nucleophile in context.
6. Proton transfer to regenerate the catalyst.

Can you figure out the acetal formation mechanism?