2-Hydroxy-3-methoxybenzaldehyde (o-vanillin) revisited

Abstract

The structure of ortho-vanillin, C[subscript 8]H[subscript 8]O[subscript 3], has been revisited with modern methods and at low temperature (100 K). The previous structure [Iwasaki et al. (1976). Acta Cryst. B32, 1264-1266] is confirmed, but geometric precision is improved by an order of magnitude. The C atom of the methoxy group lies close to the benzene ring plane, which is the most common geometry for -OMe groups lying ortho to -OH groups on an aromatic ring. The crystal structure displays one intramolecular O-H...O and three weak intermolecular C-H...O hydrogen bonds.