Oxalate, synthesis

Gershoff, S. N., and Earagalla, E. F. (1959). Endogenous oxalate synthesis and glycine, serine, deoxypyridoxine interrelationships in vitamin B6-deficient rats. /. Biol. Chem. 234, 2391-2393. 

Lloyd, W.D. et al A hydroxylation catalyst from potassium oxalate, Synthesis, 610,1972. 

Fig. 4. Effect of CO pressure on dimethyl oxalate ( ), dimethyl carbonate ( ), and dimethyl oxalate + dimethyl carbonate (A) yields for the palladium-catalyzed oxalate synthesis. From Ref. 110.

Although a number of studies have suggested that high intakes of ascorbate lead to synthesis and excretion of oxalate (Section 13.6.5.1), this seems to be the result of nonenzymic formation of oxalate in urine samples after collechon. There is no known pathway for oxalate synthesis from ascorbate. 

Dimethyl oxalate synthesis Pd/CNF Significant improvement in catalytic activity compared to Pd/AHOs. 354... 

The precise mechanism in the catalyhc oxalate synthesis has not been established, hut it is likely that the catalytic process proceeds as shown in Scheme 1.35. The catalyhc cycle is comprised of nucleophilic attack of RO on the CO coordinated to Pd(II) to give an alkoxycarhonylpalladium(II) species, which further undergoes the similar CO coordinahon followed by external RO attack to give bis(alkoxycarbonyl)palladium(ll) complex [105,106]. Reduchve eliminahon of the two alkoxycarbonyl ligands to generate a Pd(0) species and its re-oxidahon are... 

Scheme 1.35. Catalytic cycle for oxalate synthesis using alkyl nitrite.

VasyUdv, O., Sakka, Y. Nonisothermal synthesis of yttria-stabihzed zirconia nanopowder through oxalate processing 1, Chtiracteristics of Y-Zr oxalate synthesis and its decomposition. J. Am. Ceram. Soc. 83(9), 2196-2202 (2000)... 

Uranium(lV) oxalate, synthesis 45 Potassium tetraoxalatouranate (IV), synthesis 46 Barium thiocyanate, synthesis 5 Potassium octacyanomolybdate (IV) 2-hydratc, synthesis 43 Bis(lV,lV -disallcylalethylenedia-mine)-/t-aquodicobalt(II), synthesis 53... 

Gaenzler, Klaus and Schroeder report [222] that esters of oxalic acid can be produced in 90% selectivity at 60-70 C at 120 atmospheres pressure. In a typical reaction for dimethyl oxalate synthesis, an autoclave is charged with PdCl2 (1.5 g), DCl (0.75 g), anhydrous CuCU (10 g) and methanol (400g). The reactor (one-fourth filled) is pressurized with CO (100 atm.) and O2 (20 atm.) and warmed to 60 C. An exothermic reaction ensues and 37 g of dimethyl oxalate are distilled from the reaction mixture. The selectivity to the ester is 90% and the yield based on CO charged to the reactor is 9.65%. 

B. OXALATE SYNTHESIS BY CARBONYLATIVE OXIDATION B.i. Synthesis of Oxalates in Liquid Phase... 

TABLE 1. Catalyst Systems for Dialkyl Oxalate Synthesis (Liquid Phase)... 

The formation of dialkyl carbonates was observed in every case of the dialky oxalate synthesis that we discussed in the previous section. Generally, it is accepted that higher CO pressure favors dialkyl oxalate formation and lower pressure favors dialkyl carbonate formation. But in the palladium-alkyl nitrite system, we confirmed the oxidation state of... 

In Pd-catalyzed oxalate synthesis other than the palladium-alkyl nitrite system, an intramolecular coupling shown in Scheme 7 was proposed as a reaction mechanism for oxalate formation. It has been observed that the rate of oxalate formation is first order to the CO pressure in other Wacker-type reactions as well as the palladium-alkyl nitrite system. 

Osmond, C.B., Avadhani,P.N. Acid metabolism in Atriplex. II. Oxalate synthesis during acid metabolism in the dark. Aust. J. Biol. Sci. 21,917-927 (1968)... 

Williams HE, Wandzilak TE (1989) Oxalate synthesis, transport and the hyperoxaluric syndromes. J Urol 141 742-747... 

Ethylmagnesium bromide diethyl oxalate Synthesis of monohydroxytriarylmethanes... 

Reactions with Oxalate Synthesis of 2,6-Dioxabicyclo [3.3.0]-Octa-3,7- Dienes or o-Benzoquinones... 

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