Thermal decomposition of chroman. reactivity of o-quinone methide

The gas phase thermal decomposition of 3,4-dihydro-2H-1-benzopyran (chroman) between 760 and 1110 K in various bath gases and hydrogen donors was investigated. On the basis of the activation energy, it was found that the thermolysis of chroman starts with the cleavage of the phenolic C-O bond. However, the stereospecificity of the reverse reaction suggests the operation of the concerted pathway.