Preparation, properties and absolute configuration of (‐)‐allantoin

A procedure is given for the preparation and isolation of (‐)‐allantoin (5‐ureidohydantoin). A grown culture of Pseudomonas aeruginosa was incubated with (±)‐allantoin at pH 6. (+)‐Allantoin was degraded by the bacteria and (‐)‐allantoin was removed from the medium with the aid of activated carbon. Several properties of (‐)‐allantoin were determined: solubility and molar rotation in various solvents, infrared spectrum, decomposition point and dependence of the molar rotation on pH. The properties were compared with those of (±)‐allantoin, R‐ and S‐hydantoin‐5‐acetic acid. From circular dichroism measurements of (‐)‐allantoin, S‐hydantoin‐5‐acetic acid and R‐carbamoylalanine it was concluded that (‐)‐allantoin is R‐allantoin.