Patent ID: 6858743

Claim:
A process for preparing 2-coumarone or substituted 2-coumarones, characterized in is that cyclohexanone or substituted cyclohexanones of the formula I where R is H or a C 1 -C 3 -alkyl or alkoxy radical, are reacted with a carboxylic acylating agent of the general formula II where R1 and R2 are each independently hydrogen or a C 1 -C 3 -alkyl radical and R3 is a C 1 -C 3 -alkyl radical, a) to give methyl 2-(2-oxocyclohexyl)-2-hydroxyacetate or substituted methyl 2-(2-oxocyclohexyl)-2-hydroxyacetates which a 1 ) are either converted directly to 2-coumarone or substituted 2-coumarones by catalytic gas phase dehydrogenation, or a 2 ) dehydrated by azeotropic distillation under basic conditions or using a strong acid or a strongly acidic ion exchanger to give a mixture of methyl 2-oxocyclohexylideneacetate and the enol lactone of 2-oxocyclohexylideneacetic acid or a mixture of substituted methyl 2-oxocyclohexylideneacetate and the enol lactone of the substituted 2-oxocyclohexylideneacetic acid which is then in turn converted by catalytic gas phase dehydrogenation into 2-coumarone or substituted 2-coumarones, or b) reacted directly under acidic or basic conditions to give a mixture of methyl 2-oxocyclohexylideneacetate and the enol lactone of 2-oxocyclohexylideneacetic acid or a mixture of substituted methyl 2-oxocyclohexylideneacetate and the enol lactone of the substituted 2-oxocyclohexylideneacetic acid which is then in turn converted by catalytic gas phase dehydrogenation to 2-coumarone or substituted 2-coumarones.