Formation of hydrates from aldehydes/ketones and H2O

by James

Description: Addition of water to an aldehyde or ketone results in the hydrate [otherwise known as a “geminal diol”]
Content available for Reactionguide members only. Not a member? Get access for about 30 cents / day!

{ 2 comments… read them below or add one }

Carrie Douma March 23, 2015 at 1:36 pm

How would the mechanism change if this reaction were under basic or acidic conditions?

Reply

James March 23, 2015 at 6:14 pm

Hi Carrie, the difference is one extra step.

Under basic conditions, HO- would attack the carbonyl carbon in an “addition” step. Then in the second step, the resulting O- would be protonated by water to give OH
[2 steps]

Under acidic conditions, you’d protonate the carbonyl oxygen, which makes it a better electrophile. Then, water would attack the carbonyl carbon. Then, there’s be a deprotonation of the oxygen that just attacked (since now it’s R-OH2 + ) by a molecule of solvent (H2O) to give the neutral hydrate.
[3 steps]

Reply

Leave a Comment