Topochemistry. Part XXIII. The solid-state photochemistry at 25° of some muconic acid derivatives

Abstract

trans,trans-Muconic acid, its monomethyl ester, and cis,cis-isomer, all of which crystallise in cells with shortest axes of 4 Å, react in the solid state on irradiation with λ > 290 mµ. At room temperature all give vinyl-substituted cyclobutanes of symmetry m, the configuration of which reproduces the geometry of the monomer molecules both in the attachment of the ring substituents and in the configuration of the vinyl side-chain. The all-trans-acid and its monomethyl ester give, in addition to dimers, various amounts of oligomers which, according to the spectroscopic evidence, are formed by both 1,4- and 1,2-addition of the butadiene chains. Dimethyl trans,trans-muconate, which does not crystallise in a 4 Å cell, is stable to λ > 290 mµ at 25°.