(E)-Stilbene, commonly known as trans-stilbene, is an organic compound represented by the condensed structural formula CHCH=CHCH. Classified as a diarylethene, it features a central ethylene moiety with one phenyl group substituent on each end of the carbon–carbon double bond. It has an (E) stereochemistry, meaning that the phenyl groups are located on opposite sides of the double bond, the opposite of its geometric isomer, cis-stilbene. Trans-stilbene occurs as a white crystalline solid at room temperature and is highly soluble in organic solvents. It can be converted to cis-stilbene photochemically, and further reacted to produce phenanthrene. 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. Isomers 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: ), while trans-stilbene is a crystalline solid which does not melt until around , 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. CH–CH(OH)–C(=O)–CH ->[\ce{Zn(Hg)}][\ce{HCl} \text{, } \ce{CH3CH2OH}] trans-CH–CH=CH–CH Both isomers of stilbene can be produced by decarboxylation of α-phenylcinnamic acid, trans-stilbene being produced from the of the acid. Richard F. Heck and Tsutomu Mizoroki independently reported the synthesis of trans-stilbene by coupling of iodobenzene and styrene using a palladium(II) catalyst, in what is now known as the Mizoroki-Heck reaction. The Mizoroki approach produced the higher yield. Stilbene undergoes reactions typical of alkenes. Trans-stilbene undergoes epoxidation with peroxymonophosphoric acid, HPO, producing a 74% yield of trans-stilbene oxide in dioxane. The epoxide product formed is a racemic mixture of the two enantiomers of 1,2-diphenyloxirane. The achiral meso compound (1R,2S)-1,2-diphenyloxirane arises from cis-stilbene, though peroxide epoxidations of the cis-isomer produce both cis- and trans-epoxide products. For example, using tert-butyl hydroperoxide, oxidation of cis-stilbene produces 0.8% cis-stilbene oxide, 13.5% trans-stilbene oxide, and 6.1% benzaldehyde. Enantiopure stilbene oxide has been prepared by Nobel laureate Karl Barry Sharpless. Stilbene can be cleanly oxidised to benzaldehyde by ozonolysis or Lemieux–Johnson oxidation, and stronger oxidants such as acidified potassium permanganate will produce benzoic acid. Vicinal diols can be produced