Hydrogenation of butenes

A similar reactor setup was used by Keurentjes et /. 9,10 A Wilkinson catalyst with fluorinated ligands was applied in the hydrogenation of 1-butene in supercritical... 

Keurentjes et al. performed a continuous hydrogenation of 1-butene in supercritical carbon dioxide.[9,10] A fluorous derivative of Wilkinson s catalyst was prepared in situ by mixing the ligand with [(COD)RhCl]2 under hydrogen / carbon dioxide pressure (Figure 4.37). 

Figure 4.38. Continuous hydrogenation of 1 -butene in supercritical C02. (Reprinted with permission from ref. 10. Copyright 2003 Science Direct)...

A unique mechanism was suggested to interpret the difference observed in the isomerization and hydrogenation of 1-butene and ds-2-butene over a stepped Pt(775) surface.360 It was observed that the hydrogenation rates were insensitive to surface structure for both 1-butene and ds-2-butene. The isomerization rates of cis-2-butene to give only trans-2-butene on the stepped Pt(775) surface, however, was double that of 1-butene to yield both cis- and trans-2-butenes. The Horiuti-Polanyi associative mechanism, that is, the involvement of the 2-butyl intermediate (see Section 4.3.2), cannot explain this difference. However, a facile dehydrogenation of ds-2-butene to 2-butyne followed by a rehydrogenation is consistent with the experimental observations ... 

CoH(BH4)(PCy3)2] in benzene solution hydrogenates terminal alkenes and styrene faster than internal alkenes or dienes. Isomerization of terminal alkenes caused a rapid deterioration of the reaction rate.69 An ort/io-metallated triphenyl phosphite complex, for which the structure (20) was proposed, gave a turnover number of more than 300 in the hydrogenation of 1-butene. Isomerization was not observed in this case.70... 

TABLE 1. Effect of solvents on the performance of catalysts in the hydrogenation of 1-butene (pulse experiments at ambient temperature with catalysts first treated with solvent then saturated with hydrogen)... 

Hydrogenation of 1-butene to butane (T=10(y>C) Pd Pd (foil) Reaction rate is only slightly enhanced by Pd membrane Nagamoto and inoue, 1985... 

In spite of the potential advantages of the use of a catalytic membrane reactor to perform chemical reactions in SC CO2, very few references are available on this topic. The concept was however demonstrated for the hydrogenation of 1-butene using a fluorous derivative of Wilkinson s catalyst [32]. The reaction was successfully performed in a free catalyst membrane reactor equipped with a silica membrane. 

In the experiment shown in Fig. 47, it is A = 74000 and p = 26, that is, the rate of C2H4 oxidation increases by a factor of 25 and the increase in the rate of O consumption is 74000 times larger than the rate, I/2F, of O2- supply to the catalyst. In the experiment shown in Fig. 48, the maximum p values for the production of cis-2-butene, trans-2-butene, and butene are of the order of 50 and the corresponding maximum A values are of the order of 40 for cis-2-butene formation, 10 for trans-2-butene formation, and less than 1 for butene formation. Thus, each proton supplied to the Pd catalyst can cause the isomerization of up to 40 1-butene molecules to cis-2-butene and up to 10 1-butene molecules to trans-2-butene, whereas the hydrogenation of 1-butene to butane is electrocatalytic, that is, Faradaic. 

Fig. 9. Change in the composition of the butene fraction during the hydrogenation of 1-butene over palladium-alumina at Zl (31) -i- indicates thermodynamic equilibrium concentrations.

Write balanced equations for the hydrogenation of 1-butene and czs-2-butene. 

CoH P(OPh)3 3MeCN] rapidly catalyzes the hydrogenation of 1-butene (no isomerization) and it reacts spontaneously with HX generating facile dissociation of MeCN generating an un-... 

Reaction Mechanisms. Many reactions over zeolites can be described using the Langmuir-Hinshelwood formalism, which involves describing adsorption, desorption, and reaction over active sites as a series of elementary steps. Consider as an example the hydrogenation of 1-butene ... 

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