Gaseous methylglyoxal has two carbonyl groups, an aldehyde and a ketone. The released alcohol is susceptible to oxidation to the aldehyde and carboxylic acid. Oximes can be synthesized by condensation of an aldehyde or a ketone with hydroxylamine. The reaction of NHOH with an aldehyde or ketone produces an oxime. Metabolism involves first oxidation by monoamine oxidase to the corresponding aldehyde. The hydroboration of alkynes gives vinylic boranes which oxidize to the corresponding aldehyde or ketone. Further hydrolysis will yield an aldehyde and ammonia. The molecule consists of a benzene ring attached to an unsaturated aldehyde. Allylic alcohols can be prepared by reaction of the betaine ylide with a second aldehyde. They essentially contain an aldehyde or ketone group in their structure. His4 catalyzes the oxidation of -histidinol to form -histidinal, an amino aldehyde. Another route involves the hydroformylation of epoxides followed by hydrogenation of the aldehyde. Glutamic acid was converted to the necessary aldehyde via Strecker degradation. The mechanism involves a tyrosine residue in the active site of aldehyde reductase. The general scheme is a condensation and oxidation process starting with pyrrole and an aldehyde.