betahidroxi

Betahidroxi, also written beta-hidroxi, is a chemical descriptor used in organic chemistry to denote the presence of a hydroxyl (-OH) group on the beta carbon relative to a reference functional group, most commonly a carboxyl group. It is not a single compound but a structural motif that appears in several classes of compounds, including beta-hydroxy acids, beta-hydroxy ketones, and beta-hydroxy alcohols. In aliphatic carboxylic acids, the beta carbon is the third carbon away from the carboxyl carbon, so a hydroxy substituent on that carbon gives a beta-hydroxy acid, such as 3-hydroxypropanoic acid or 3-hydroxybutanoic acid. In metabolism, beta-hydroxybutyrate (β-hydroxybutyrate) is a ketone body that serves as an energy source during fasting or ketogenic states.

Beta-hydroxy motifs also arise as intermediates in aldol reactions, where β-hydroxy carbonyl compounds are formed. In biology, beta-hydroxy acids are found in certain metabolic pathways and can serve as precursors to short-chain polyesters in some microorganisms. In polymer chemistry, beta-hydroxy acids are of interest as monomers for biodegradable polyesters. The presence of a beta-hydroxyl group influences acidity, nucleophilicity, and the potential for intramolecular lactone formation, such as beta-lactones under dehydrating conditions.

See also: beta-hydroxy acid, beta-hydroxy ketone, beta-lactone, aldol reaction.