Mild water-promoted selective deacetalisatison of acyclic acetals

Various aliphatic and aromatic dimethyl and diethyl acetals and ketals were found to hydrolyse in essentially quantitative yield when heated to 80 degrees C in neat water or aqueous medium without a catalyst or any other additive, while cyclic acetals were stable under these conditions. Selective deprotection is possible when both types of acetal are present.