An economical and convenient synthesis of 7-oxabicyclo[2.2.1]heptane

A high-yield process for converting hydroquinone into 7-oxabicyclo[2.2.1]heptane by hydrogenation over RhAl2O3, isomerizing the cis-trans mixture of 1,4-cyclohexanediols into all-trans by treatment with sodium, and ring closure over A4 zeolites was demonstrated on mini-plant scale. Long-term continuous operation of the ring closure reactor gave no problems. The rhodium catalyst is poisoned after short use. Regeneration by mild oxidative treatment was demonstrated for Rh/C catalysts.