acyloin

thumb|right|The structure of a typical acyloin.

In organic chemistry, acyloins or α-hydroxy ketones are a class of organic compounds of the general form , composed of a hydroxy group () adjacent to a ketone group (). The name acyloin is derived from the fact that they are formally derived from reductive coupling of carboxylic acyl groups (). They are one of the two main classes of hydroxy ketones, distinguished by the position of the hydroxy group relative to the ketone; in this form, the hydroxy is on the alpha carbon, explaining the secondary name of α-hydroxy ketone.