Comparative study of hydrogenolysis of a C-X bond in three homologous heterocyclic compounds of chemical formula C5H10X with X = S, O and NH

Abstract

A theoretical study of hydrogenolysis of a C-X bond of 2-methyltetrahydrothiophene (2-MTHT), 2-methyltetrahydrofuran (2-MTHF) and 2-methylpyrrolidine (2-MP) molecules, over molybdenum disulfide (MoS 2 ) and tungsten disulfide (WS 2 ) has been performed by MP2 calculations in the Lanl2DZ basis set. Both catalysts were modeled by catalytic sites with three anionic vacancies MoS 3 H 3 + and WS 3 H 3 + respectively. The temperature and pressure conditions respected in the study are respectively 573 K and 70 atm. The obtained results shown that, the Hydrogenolysis of a C-X bond of methyled carbon of 2-MTHT and 2-MTHF molecules led to the formation of 1-pentanethiol and 1-pentanol adsorbed over the each catalyst. On the other hand, in the case of the 2-MP molecule, the catalytic site was implicated in the reaction with formation of hydrogen sulfide (H 2 S). The Hydrogenolysis activation energies of various transformations were variable from MoS 2 to WS 2 catalysts except for 2-MTHT. In presence of a same kind of catalyst, the activation energies of Hydrogenolysis of the C-X bond (methyled carbon atom) of 2-MTHF and 2-MTHT increase in the order X = O, S.