"wherein each R1 is independently a hydrogen or a C1-C12 hydrocarbyl group, and R2 is a hydrogen, a C1-C12 hydrocarbyl group, or a halogen; wherein the heterogeneous catalyst comprises a metal oxide composition in combination with a porous support, wherein the metal is molybdenum, tungsten, or a combination comprising at least one of the foregoing metals." . . . . .