Crystal structures of 1,2,5-trimethoxy-3-(1-propenyl)benzene and 1,3,5-trimethoxy-2-(1-propenyl)benzene

The crystal structures of 1,2,5-trimethoxy-3-(I-propenyl)benzene (D) and 1,3,5-trimethoxy-2-(1-propenyl)benzene (F) have been determined by X-ray diffraction methods. The compounds crystallize in the monoclinic system, space group P2(1)/c for (D) with a = 8.173(2), b = 11.725(2), c = 12.275(2) Angstrom, beta = 102.48(3)degrees, V= 1148.5(4) Angstrom(3), and P2(1)/n for (F) with a = 7.433(1), b = 18.225(4), c = 8.854(2) A, beta = 108.51(3)degrees, V = 1137.4(4) Angstrom(3). Both, (D) and (F), carry E-propenyl side chains. The double bond lengths observed in the propenyl groups of the compounds examined (1.307(3) and 1.281(4) Angstrom) deviate from the expected value (approximate to 1.34 Angstrom). The angular deformation parameters were used in the analysis of the deformations of angles in the benzene ring. The existence of intra- and intermolecular C-H .... O hydrogen bonds was observed.