Ethane/ethene hydride transfer

Another study of ethane/ethene hydride transfer was performed to investigate the influence of the Si/Al ratio and different levels of coverage of the acid sites... 

In zeolites, this barrier is even higher. As discussed in Section II.B, the lower acid strength and the interaction between the zeolitic oxygen atoms and the hydrocarbon fragments lead to the formation of alkoxides rather than carbenium ions. Thus, extra energy is needed to transform these esters into carbonium ionlike transition states. Quantum-chemical calculations of hydride transfer between C2-C4 adsorbed alkenes and free alkanes on clusters representing zeolitic acid sites led to activation energies of approximately 200 kJ/mol for isobutane/tert-butoxide (29), 230-305 kJ/mol for propane/sec-propoxide, and 240 kJ/mol for isobutane/tert-butoxide (32), 130-150 kJ/mol for ethane/ethene (63), 95-105 kJ/mol for propane/propene, 88-109 kJ/mol for isobutane/isobutylene, and... 

Concomitant with continued olefin insertion into the metal-carbon bond of the transition metal aluminum complex, alkyl exchange and hydrogen-transfer reactions are observed. Whereas the normal reduction mechanism for transition metal organic complexes is initiated by release of olefins with formation of a hydride followed by hydride transfer to an alkyl group, a reverse reaction takes place in the case of some titanium and zirconium acompounds. A dimetalloalkane is formed by the release of ethane. In second step, ethene is evolved from the dimetalloalkane ... 

Mar9alo et al. (2011) performed a systematic study of the reactivities of the dipositive actinide ions Th to Cm with methane, ethane, propane, n-butane, ethene, propene, and 1-butene. All of the studied An exhibited significant net reactivities with at least some of the hydrocarbons, with the observed reactions given by Eqs. (9)-(16), where (9) is adduct formation, (10)-(13) are bond activation, (14) is electron transfer, (15) is hydride transfer, and (16) is methide transfer ... 

---