Solid-state structure of 1,2-dimethoxybenzene (veratrole) and related methoxybenzenes. X-Ray crystallography and 13C nuclear magnetic resonance tensor analysis

Abstract

We present here the single crystal X-ray structure of 1,2-dimethoxybenzene which reveals the methoxy groups to be trans and twisted out of the plane by –5.0 and 8.6°. Using variable spinning rate ¹³C CP MAS NMR spectroscopy, the principal shielding tensors were measured for anisole, 1,2-dimethoxybenzene, 1,4-dimethoxybenzene and 1,3,5-trimethoxybenzene. From this work the principal elements were obtained for static benzene (σ₁₁= 222, σ₂₂= 147 and σ₃₃= 14) and for the substituent chemical shift of a planar methoxy group. The ab initio tensors of 1,2-dimethoxybenzene were calculated by the GIAO and LORG methods using the X-ray data as input. The CP MAS spectrum of 1,3-dimethoxybenzene reveals that this molecule adopts the asymmetric planar conformation.