Hydrogen bonding of catechol groups in the crystal structure of dihydrocaffeic acid

Abstract

Dihydrocaffeic acid C₉H₁₀O₄ is a natural antioxidant. The crystal structure of dihydrocaffeic acid is determined; the crystallographic data at 100 K are: a = 11.3189(4) ?, b = 5.5824(1) ?, c = 13.8431(4) ?, β = 109.248(4)°, and V = 825.80(4) ?³; the space group is P2₁/c, Z = 4. In addition to the formation of hydrogen bonds that are typical of acids, the compound has features that are important from the viewpoint of reactivity of dihydrocaffeic acid molecules. The position of one of the hydroxyl hydrogen atoms in the catechol group is disordered even at 100 K. The crystal structure of caffeic acid does not show such a disordering.