Selective hydrogenation of myrcene catalyzed by sol-gel Pd/SiO2

Sol-gel palladium silica composites are active catalysts for the selective hydrogenation of myrcene. The temperature of the thermal treatment of the catalyst is essential for its selectivity. Catalysts treated at 1100 °C give monohydrogenated products with excellent combined selectivity of 90-95% at almost complete conversion of the substrate. The obtained products arise from the σ-alkyl and/or η3-allyl intermediates formed by the interaction of the palladium catalyst with both terminal CC bonds of myrcene and the main products (ca. 70%) result from the reaction with the less substituted one. The selective monohydrogenation of myrcene could be useful to produce a mixture of diolefins of different reactivity, which could be further transformed to oxygenated derivatives with selectivities better than myrcene itself.