Ruthenium containing hydrotalcite as a solid base catalyst for >C [dbnd]C< double bond isomerization in perfumery chemicals

Abstract

Ruthenium containing hydrotalcite (Ru–Mg–Al) is used as a solid base catalyst for >C C< double bond isomerization of methyl chavicol, eugenol, safrole, allylbenzene, dimethoxy allylbenzene and 3-carene. The catalyst showed excellent conversion and selectivity for isomerization reaction in shorter reaction time (2 h). Catalytic activity and reusability of Ru–Mg–Al was compared with ruthenium impregnated catalysts such as, Ru–HT, Ru–MgO, Ru–CaO, Ru–SiO 2 and Ru–alumina for isomerization of methyl chavicol to trans-anethole. Ru–Mg–Al catalyst was reused four times without loss in its activity, however, significant loss in the conversion of methyl chavicol and selectivity of trans-anethole was observed on reusability of other ruthenium impregnated catalysts. The conversion of methyl chavicol and selectivity of trans-anethole was found to increase on increasing the reaction temperature as well as amount of catalyst. At 0.005 g catalyst amount, 55% conversion of methyl chavicol with 68% selectivity of trans-anethole was observed that increased to 93% with 82% selectivity of trans-anethole at 0.05 g catalyst amount. On further increase in the amount of catalyst to 1 g, conversion increased to 98% with 88% selectivity of trans-anethole.