Degradation
The effect of heat, sunlight, radicals and oxidants on isomerisation of the
double bonds has been investigated. The compound is degraded by
heating at 50 °C (6 mg remained of 100 mg after 6 days) but the process
may be slowed by the addition of antioxidants. Isomerisation occurs readily
in sunlight in the presence of a photosensitiser. Within 100 minutes an
equilibrium mixture containing 76% E,E and 12-14% of each of the
E,Z- and Z,E-isomers was formed. In the absence of photosensitiser,
degradation was faster than photoequilibration. Photo-oxidation in the
presence of Rose Bengal as a singlet oxygen generator gave a furan
derivative (4) (see Scheme 1). This takes place after isomerisation of 1 to
the E,E-isomer (3) (Shani et al., 1981).