Stilbene was discovered in 1843 by the French chemist Auguste Laurent. The name "stilbene" is derived from the Greek word στίλβω (stilbo), which means "I shine", on account of the lustrous appearance of the compound.
The isomerization of stilbene under the influence of radiation.
Stilbene exists as two possible stereoisomers. One is trans-1,2-diphenylethylene, called (E)-stilbene or trans-stilbene. The second is cis-1,2-diphenylethylene, called (Z)-stilbene or cis-stilbene, and is sterically hindered and less stable because the steric interactions force the aromatic rings out-of-plane and prevent conjugation.Cis-stilbene is a liquid at room temperature (melting point: 5–6 °C (41–43 °F)), while trans-stilbene is a crystalline solid which does not melt until around 125 °C (257 °F), illustrating the two isomers have significantly different physical properties.
Preparation and reactions
Many syntheses have been developed. One popular route entails reduction of benzoin using zinc amalgam.
Bromination of trans-stilbene produces predominantly meso-1,2-dibromo-1,2-diphenylethane (sometimes called meso-stilbene dibromide), in line with a mechanism involving a cyclic bromonium ion intermediate of a typical electrophilic bromine addition reaction;cis-stilbene yields a racemic mixture of the two enantiomers of 1,2-dibromo-1,2-diphenylethane in a non-polar solvent such as carbon tetrachloride, but the extent of production of the meso compound increases with solvent polarity, with a yield of 90% in nitromethane. The formation of small quantities of the two enantiomers of stilbene dibromide from the trans-isomer suggests that the bromonium ion intermediate exists in chemical equilibrium with a carbocation intermediate PhCHBr–C+(H)Ph with a vacant p orbital vulnerable to nucleophilic attack from either face. The addition of bromide or tribromide salts restores much of the stereospecificity even in solvents with a dielectric constant above 35.
^Laurent, Auguste (1843). "Mémoire sur la série stilbique" [Memoir on the stilbene series]. Comptes rendus (in French). 16: 856–860. From p. 857: "En soumettant ce sulfure à la distillation, il donne plusieurs produits, et entre autres, un composé fort remarquable que je nomme stilbène."
(On submitting this sulfide [i.e., phenyl thioaldehyde, C6H5(CS)H] to [dry] distillation, it gives several products, and among others, a very remarkable compound which I name "stilbene".)
^Ogata, Yoshiro; Tomizawa, Kohtaro; Ikeda, Toshiyuki (1979). "Oxidation of trans-stilbene with peroxymonophosphoric acid". J. Org. Chem.44 (14): 2362–2364. doi:10.1021/jo01328a006.
^Yin, Guochuan; Danby, Andrew M.; Kitko, David; Carter, John D.; Scheper, William M.; Busch, Daryle H. (2007). "Olefin Epoxidation by Alkyl Hydroperoxide with a Novel Cross-Bridged Cyclam Manganese Complex: Demonstration of Oxygenation by Two Distinct Reactive Intermediates". Inorg. Chem.46 (6): 2173–2180. doi:10.1021/ic061957r. PMID17295471.
^Buckles, Robert E.; Bader, Jane M.; Thurmaier, Roland J. (1962). "Stereospecificity of the Addition of Bromine to cis- and trans-Stilbene". J. Org. Chem.27 (12): 4523–4527. doi:10.1021/jo01059a097.
^Bianchini, Roberto; Chiappe, Cinzia (1992). "Stereoselectivity and reversibility of electrophilic bromine addition to stilbenes in chloroform: influence of the bromide-tribromide-pentabromide equilibrium in the counteranion of the ionic intermediates". J. Org. Chem.57 (24): 6474–6478. doi:10.1021/jo00050a021.