N.m.r. study of reversible hydration of aliphatic aldehydes and ketones. Part 3.—Isotopic oxygen exchange of acetone

Abstract

The rate of oxygen exchange of acetone in aqueous solution was measured by the ¹⁷O n.m.r. technique. Measurements were done in acetate, phosphate, borate and bicarbonate buffers. The H⁺ and OH^–-catalysis rate constants were 16.5 and 55 M^–1 sec^–1 respectively. For the acetate and phosphate buffers, general acid but not general base catalysis was detected. The results in borate and bicarbonate buffers did not allow conclusions to be drawn regarding general catalyses in these buffers. The results are discussed in terms of the hydration-dehydration reaction of the carbonyl group and are compared with those for formaldehyde and acetaldehyde. Some measurements on the isotopic oxygen exchange of isopropylmethyl ketone and pinacolone with water are also reported.