Fumaric acid, catalyzed hydrogenation

In aqueous hydrochloric acid solutions, mthenium(II) chloride catalyzed the hydrogenation of water-soluble olefins such as maleic and fumaric acids [6]. After learning so much of so many catalytic hydrogenation reactions, the kinetics of these simple Ru(II)-catalyzed systems still seem quite fascinating since they display many features which later became established as standard steps in the mechanisms of hydrogenation. The catalyst itself does not react with hydrogen, however, the mthenium(II)-olefin complex... 

Figure 3.2b, The effect of pH on the initial rate of hydrogenation of fumaric acid (FA) catalyzed by [RhCl(TPPMS>3] in aqueous solution. [Rh]=5.2 x lO" M, [FA1=0.05 M, 60 C, Hi, 1 bar total pressure. The calculated distribution (a%) of nondissociated (H A) and dissociated (HA , fumaric acid is also shown. Reprinted with permission from Chem. Eur. J. 2001, 7, 193. Copyright (2001) Wiley-VCH Verlag GmbH.

Early experiments concerned the enzymatic hydrogenation of fumaric acid to succinic acid, catalyzed by either yeast 24,55 or enzyme extracts from yeast cells56. Much later, strains of Escherichia coli, Aerobacter aerogenes and Aerobacter cloacae were shown to have the same ability 57,58. An interesting mixed culture fermentation has been developed, where the fungus Rhizopus chinensis produces fumaric acid from glucose and a selected E. coli converts the previously formed fumaric acid into succinic acid58. 

The hydrogenation of acetylenedicarboxylic acid dimethyl ester (80) and diphenylacetylene (83) with [RhH2(0C(==0)0H)(PPr 3)2] gives dimethyl fumarate (82) and fraws-stilbene (84), respectively. This complex also catalyzes an isomerization of ds-stilbene to fra s-stilbene, though hydrogenation of alkyne is about eight times faster than the isomerization. ... 

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