The crystal and molecular structure of cannabidiol

Abstract

The structure of cannabidiol, C21H30O2, has been determined by X-ray methods using 2046 reflections collected by counter methods. The compound crystallizes in the space group P21 with two molecules in the asymmetric unit. Cell dimensions are a=10.644(5) Å, b=10.667(2) Å, c=17.323(5) Å, β=95.42(3)°. The structure model was refined to a conventional R of 0.073. The cyclohexene ring is in the half-chair conformation. The aryl and the isopropenyl substituents are quasi-equatorial and the conformation around the pivot bonds are syn-periplanar relative to the quasi-axial protons. The main difference between the two molecules in the asymmetric unit is in the conformation of the pentyl side-chain. The molecules are kept together mainly by van der Waals forces. There is only one hydrogen bond [2.861(8) Å] which connects the phenolic groups in the two molecules in the asymmetric unit.