AN EXAMPLE OF THE VALORIZATION OF TERPENES - THE SELECTIVE ISOMERIZATION OF 3-CARENE TO 2-CARENE IN THE PRESENCE OF SILICA-SUPPORTED NICKEL-CATALYSTS MODIFIED BY TETRABUTYL TIN
P. Lesage et al., AN EXAMPLE OF THE VALORIZATION OF TERPENES - THE SELECTIVE ISOMERIZATION OF 3-CARENE TO 2-CARENE IN THE PRESENCE OF SILICA-SUPPORTED NICKEL-CATALYSTS MODIFIED BY TETRABUTYL TIN, Journal of molecular catalysis. A, Chemical, 112(2), 1996, pp. 303-309
The cyclic olefin, 3-carene, undergoes an isomerization of the carbon-
carbon double bond to produce 2-carene, a precursor in the synthesis o
f(-)-menthol. This isomerization is observed over silica supported nic
kel, but the selectivity is reduced by side reactions producing trimet
hylheptenes by hydrogenative ring opening of the cyclopropyl ring. Sel
ectivity for C=C bond isomerization is dramatically increased by surfa
ce modification of the nickel metal catalyst by reaction with tetra-n-
butyl tin, The most selective of these silica supported nickel/tin cat
alysts produces 2-carene with 91% selectivity at 48% conversion.