The chemistry of dispirotetraenediones

A literature survey of the oxidative coupling of phenols and phenolic ethers has been carried out and is included. The thermal decomposition of dispiro-(5,0,5,3)-pentadeca-1,4,8,11-tetraene-3,10-dione, prepared by oxidation of the appropriate diphenol, has been studied in both solution and in the solid state. The decomposition in ethanol occurs by approximately first order kinetics at 74°C, the rate is not completely insensitive to concentration, however, suggesting a second order component. Decomposition in benzene is kinetically less regular: it is characterised by a slow initial phase followed by a more rapid reaction leading to complete decomposition. Addition of benzoyl peroxide has no effect on the decomposition rate in benzene; however, addition of 2,6-di-t-butyl-4-methyl phenol accelerates the decomposition in both benzene and ethanol. [Continues.]