18952-28-8Relevant academic research and scientific papers
HYDROGENOLYSE EN PHASE LIQUIDE SUR Pd/C DES EPOXYDES DU CARVOMENTHENE ET DU LIMONENE
Accrombessi, G.,Geneste, P.,Olive, J.-L.,Pavia, A. A.
, p. 3135 - 3140 (2007/10/02)
Hydrogenolysis over Pd/C of cis and trans epoxides of carvomenthene and limonene give a mixture of hydrocarbons, secondary and tertiary alcohols, and ketones in proportions dependent upon the nature of the starting material.In the limonene epoxides, the extracyclic double bond plays an important role in the opening of the oxirane ring through a common unsaturated tertiary alcohol intermediate by double bond migration, hydrogenation of which leads to the products.For the carvomenthene epoxides the results are similar to those found in the 4-t-butyl series with competition between cis addition and trans addition of hydrogen.The presence of the isopropenyl group leads to slower reaction rates in comparison with t-butyl analogues.
Mechanism of the Liquid-Phase Catalytic Hydrogenolysis on Palladium/Carbon of Cyclohexene Epoxides
Accrombessi, Georges C.,Geneste, Patrick,Olive, Jean-Louis,Pavia, Andre A.
, p. 4139 - 4143 (2007/10/02)
Heterogeneous catalytic hydrogenolysis of cyclohexene epoxides on 10percent Pd/C was studied in different solvents. The principal products were found to be alcohols, formed by cleavage of one epoxide C-O bond. In addition, simultaneous cleavage of both C-O bonds gave hydrocarbons, and isomerization on the catalyst gave ketones as byproducts. The deuterolysis of cis- and trans-tert-butylcyclohexene epoxides and kinetic studies with cyclohexene epoxides carrying an axial methyl group in position 3 or 5 showed that hydrogenolysis gives preferentially axial alcohols and trans hydrogen addition, after a "roll over" on the catalyst. If one epoxide carbon carries a methyl group, conformational and steric factors come into play. C-O bond cleavage at the more substituted carbon, leading to equatorial alcohols, becomes competitive with preferential formation of axial alcohols, and steric hindrance to molecular reorientation on the catalyst causes cis as well as trans hydrogen addition.
