The photochemistry of di-p-cumenylfulgide (bis-p-cumenylmethylenesuccinic anhydride)

Abstract

The photochemistry of the title compound in the solid and in solution at low temperatures has been investigated. The solid E,E-isomer gives the E,Z-isomer plus a dimer F; one crystal form of the E,E-isomer is reversed photochromic. The solid Z,Z-isomer also gives the dimer F, whereas the E,Z-isomer appears to give the E,E-isomer as the primary photoproduct. In methylcyclohexane–isohexane at –185°, the E,E-isomer is isomerised to E,Z; the latter is reversibly isomerised into Z,Z but also gives two dimers, one of them F. At –100° the same isomerisation processes occur, with in addition reversible conversion of the E,Z-isomer into the 1,8a-dihydrophenylnaphthalene. At these low temperatures the isomerisation of the E,E- to the Z,Z-isomer proceeds via the E,Z-form. The isomerisation processes do not proceed through the dihydrophenylnaphthalenes or cyclobutenes.