Thermal decomposition of citraconic anhydride

Abstract

Citraconic anhydride decomposes in the gas phase over the range 440- 490° to give carbon dioxide, carbon monoxide, and propyne which undergoes some polymerization to trimethylbenzenes. The decomposition obeys first-order kinetics, and the Arrhenius equation                     k₁ = 10^15.64 exp(-64233±500/RT) (s^-1) describes the variation of rate constant with temperature. The rate constant is unaffected by the addition of isobutene or by increase in the surface/volume ratio of the reaction vessel. The reaction appears to be unimolecular and if a diradical intermediate is involved it may not be fully formed in the transition state.