Crystal and Molecular Structures of Allocinnamic Acid

• Published in: Bulletin of the Chemical Society of Japan Vol. 67; no. 5; pp. 1475 - 1478
• Main Authors: Lee, Ho-Hi, Senda, Hitoshi, Kuwae, Akio, Hanai, Kazuhiko
• Format: Journal Article
• Language: English
• Published: Tokyo The Chemical Society of Japan 01.05.1994; Chemical Society of Japan
• Subjects: Aliphatic, non-condensed and condensed benzenic, and alicyclic compounds; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Organic compounds; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; X-ray absorption spectroscopy: exafs, nexafs, xanes, etc; X-ray diffraction and scattering; Vinyl monomers; Molecular structure; Benzenic compound; Carboxylic acids; NMR spectra; XRD; Experimental study; Carbon 13; Organic compounds; Crystal structure
• ISSN: 0009-2673; 1348-0634
• DOI: 10.1246/bcsj.67.1475

Crystals of allocinnamic acid having a melting point of 68 °C are monoclinic: space group P21/n with a = 10.157(4), b = 9.798(2), c = 15.770(4) Å, β = 91.35(3)°, and Z = 8. The structure was solved by direct method and refined to a final R value of 0.059 for 3832 reflections [I > 3σ(I)]. There are two independent molecules (A, B) in the asymmetric unit. The two molecules are hydrogen bonded through carboxylic acid groups [O1A···O2B 2.643(5) Å, O2A···O1B 2.629(5) Å]. Geometric differences between the two molecules are found in the torsion angle around the C(phenyl)–C(olefin) bond and the olefinic C=C bond length. In the high-resolution solid-state 13C NMR spectra resonances for the C2, C3, and C4 carbons are observed as doublet features in accordance with the conformational variations observed in X-ray crystallography.