Fumarate formation from

Hydration and Dehydration. Maleic anhydride is hydrolyzed to maleic acid with water at room temperature (68). Fumaric acid is obtained if the hydrolysis is performed at higher temperatures. Catalysts enhance formation of fumaric acid from maleic anhydride hydrolysis through maleic acid isomerization. 

The a—time curves for the oxidation reactions [60] of both nickel maleate (534—568 K) and nickel fumarate (548—583 K) were similar to those characteristic of each reactant in vacuum, though E values were reduced to 150 10 kJ mole-1. It was concluded that the distributions of nucleation sites and subsequent patterns of product development were little altered by the change in composition of product from Ni/C (and Ni3C) to NiO. This difference, however, significantly changed the temperature coefficient and stoichiometry of the interface processes, since all carbonaceous material in the reactants was converted to CO2. A constant value of E (150 kJ mole-1) was thus found for the oxidations of the four nickel salts studied [60], the maleate, fumarate, formate and malonate. 

The AH° value for oxidation of fumaric acid (HOOC—CH=CH—COOH) is -1336 kJ mol . Calculate the enthalpy of formation (AHj) of fumaric acid from its elements, given the following data ... 

In the early 1960s, Brannock et al. reported a thermal [2+2] cycloaddition of enamines. Enamines react with a variety of electron-deficient alkenes such as acrylates, nitro-olefines, acetonitriles, vinylsulfones, fumarates, and malei-mides to give aminocyclobutanes [4]. The reaction generally does not require the assistance of an acid catalyst. Narasaka et al. exploited asymmetric thermal [2+2] cycloaddition of vinyl and aUenyl sulfides with electron-deficient alkenes catalyzed by Lewis acid [5]. Yamazaki et al. have reported that a stoichiometric amount of Lewis acid activates [2+2] cycloaddition of vinylselenides with highly electron-deficient olefins [6]. These reactions proceed via a stepwise annulation to give mercapto- and seleno-cyclobutanes, respectively. However, cyclobutane formation from silyl enol ethers, which are one of the most easily prepared ketone... 

Biegert T, G Fuchs, J Heider (1996) Evidence that anaerobic oxidation of toluene in the denitrifying bacterium Thauera aromatica is initiated by formation of benzylsuccinate from toluene and fumarate. Eur J Biochem 238 661-668. 

Figure 3 Gradient separation of anions using suppressed conductivity detection. Column 0.4 x 15 cm AS5A, 5 p latex-coated resin (Dionex). Eluent 750 pM NaOH, 0-5 min., then to 85 mM NaOH in 30 min. Flow 1 ml/min. 1 fluoride, 2 a-hydrox-ybutyrate, 3 acetate, 4 glycolate, 5 butyrate, 6 gluconate, 7 a-hydroxyvalerate, 8 formate, 9 valerate, 10 pyruvate, 11 monochloroacetate, 12 bromate, 13 chloride, 14 galacturonate, 15 nitrite, 16 glucuronate, 17 dichloroacetate, 18 trifluoroacetate, 19 phosphite, 20 selenite, 21 bromide, 22 nitrate, 23 sulfate, 24 oxalate, 25 selenate, 26 a-ketoglutarate, 27 fumarate, 28 phthalate, 29 oxalacetate, 30 phosphate, 31 arsenate, 32 chromate, 33 citrate, 34 isocitrate, 35 ds-aconitate, 36 trans-aconitate. (Reproduced with permission of Elsevier Science from Rocklin, R. D., Pohl, C. A., and Schibler, J. A., /. Chromatogr., 411, 107, 1987.)...

The EfZ ratio of stilbenes obtained in the Rh2(OAc)4-catalyzed reaction was independent of catalyst concentration in the range given in Table 22 357). This fact differs from the copper-catalyzed decomposition of ethyl diazoacetate, where the ratio diethyl fumarate diethyl maleate was found to depend on the concentration of the catalyst, requiring two competing mechanistic pathways to be taken into account 365), The preference for the Z-stilbene upon C ClO -or rhodium-catalyzed decomposition of aryldiazomethanes may be explained by the mechanism given in Scheme 39. Nucleophilic attack of the diazoalkane at the presumed metal carbene leads to two epimeric diazonium intermediates 385, the sterically less encumbered of which yields the Z-stilbene after C/C rotation 357,358). Thus, steric effects, favoring 385a over 385 b, ultimately cause the preferred formation of the thermodynamically less stable cis-stilbene. 

Aratani et al. (21) subsequently found that the use of chiral menthyl diazoacetate esters led to higher trans/cis ratios and improved facial selectivity. A number of bulky diazoesters provided high enantioselectivity in the cyclopropanation reaction, but trans selectivity was highest with /-menthyl esters, Eq. 6. It seems clear from these and subsequent studies that the menthyl group is used because of its bulk and ready availability. The chirality present in the ester has a negligible effect on facial selectivity in the cyclopropanation reaction. Slow addition of diazoester is required (7 h at ambient temperature) for high yields presumably to suppress the formation of fumarate byproducts. 

When the reaction is conducted in the presence of added fumarate, the yield of pyrrolidine (130) increases at the expense of the aziridine. Jacobsen suggests that the aziridines and pyrrolidines arise from a common intermediate, azo-methine ylide (132), Scheme 6, which may also be partly responsible for the poor levels of asymmetric induction in this reaction. Electrocyclic ring closure of the azo-methine while still within the coordination sphere of the metal (131) may provide aziridine with some induction, while decomplexation (132) will lead to the formation of racemic aziridine and pyrrolidine. 

In the [2 + 2] cycloadditions of 10 with iV-phenylmaleimide and dimethyl fumarate, the major cycloadducts were formed with a very high degree of ee transfer from 1,3-dimethylallene8. Similar results were obtained in the reaction of 10 with 1,1-dichloro-2,2-difluoroethene. The reaction with less reactive 1,1-diphenylethene did not lead to cycloadduct formation, but resulted in racemization of the chiral 1,3-dimethylallene instead9, which implies reversible formation of the diradical intermediate in this case. Finally, the cycloaddition of 1,3-dimethylallene to methyl propiolate (14) afforded two cycloadducts, 15 and 16, to which >40% of the initial ee had been transferred (equation 5)11. 

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