In organic chemistry, 3-hydroxybutanal (acetaldol****, aldol) is an organic compound with the formula CH3CH(OH)CH2CHO and the structure H3C\sCH(OH)\sCH2\sCH\dO. It is classified as an aldol (R\sCH(OH)\sCHR'\sC(\dO)\sR") and the word "aldol" can refer specifically to 3-hydroxybutanal. It is formally the product of the dimerization of acetaldehyde (CH3CHO). A thick colorless or pale-yellow liquid, it is a versatile and valuable intermediate with diverse impacts. The compound is chiral although this aspect is not often exploited.

Production

Acetaldehyde dimerizes upon treatment with aqueous sodium hydroxide: This is the prototypical aldol reaction.

Reactions and uses

Dehydration of 3-hydroxybutanal gives crotonaldehyde. Distillation of 3-hydroxybutanal is sufficiently forcing to effect this conversion: Hydrogenation of 3-hydroxybutanal gives 1,3-butanediol: This diol is a precursor to 1,3-butadiene, precursor to diverse polymers. Polymerization of 3-hydroxybutanal is also spontaneous, but can be stopped with the addition of water. Aldol has been used in making perfumes and in ore flotation.

Former or niche uses

It was formerly used in medicine as a hypnotic and sedative.