Reactions of 3-methylpentane, 3-methyl-1-pentene, cis- and trans-3-methyl-2-pentenes have been studied over a platinum black catalyst, in a pulse-microcatalytic system, in the presence of carrier gases with different hydrogen contents. The yields of dehydrogenation of 3-methylpentane, C5-cyclization, skeletal isomerization, and benzene formation are discussed in detail as a function of hydrogen pressure. An enhanced reactivity of the terminal olefinic double bond has been observed under hydrogen-deficient conditions: this manifested itself as benzene formation (presumably in bond-shift type dehydro-isomerization reaction) as well as in "non-hydrogenative" C5-cyclization resulting in 1-methylcyclopentene. On the other hand, "hydrogenative" mechanisms of C5-cyclization and C5-cyclic isomerization have been found to prevail in the presence of more hydrogen; a common half-hydrogenated intermediate for both saturated and unsaturated hydrocarbons and a "dual-site" mechanism has been proposed for this process.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry