Sodium mesoxalate

The condensation of a-ketoacids and o-phenylenediamines gives quinoxalin-2-ones,7 and mesoxalic acid and o-phenylenediamine undergo the expected condensation reaction to give quinoxalin-3-one-2-carboxylic acid (1). With sodium mesoxalate an anomalous reaction occurs, the initial products (1) and l,2-dihydrobenzimidazole-2,2-dicarboxylic acid (2) undergo an intermolecular hydrogen transfer reaction to yield l,2,3,4-tetrahydro-3-oxoquinoxaline-2-carboxylic acid (3) and benzimidazole-2-carboxylic acid (4).8... 

Although the condensation of mesoxalic acid with o-phenylenediamine and N-methyl-o-phenylenediamine hydrochloride proceeds in an analogous manner, when sodium mesoxalate is reacted with o-phenylenediamine and the reaction mixture is acidified, the reduced acid 3 and benzimidazole-2-carboxylic acid (4) are formed. The primary products of reaction are thought to be the expected quinoxalinonecarboxylic acid (1) and the dihydrobenzimidazoledicarboxylic acid (2). Reduction of the quinoxalinonecarboxylic acid is thought to involve the dihydro-... 

Mesoxalic acid (or ketomalonic acid) is a good chelating agent and potentially a valuable synthon for organic synthesis. It has been prepared by oxidation of sodium tartronate on PtBi/C catalyst at 60 °C without pH control the maximum yield was 65% at 80% conversion [67]. Operating at 80 °C, 50% mesoxalic acid was obtained at total conversion of tartronic acid. The solution was free from other oxidation products, which were totally oxidized to CO2. 

Biilow and Ganghofer330 obtained dimethyl mesoxalate phenylhydrazone by adding a diazonium salt solution prepared from aniline (12 g), 30% hydrochloric add (36 g), ice + water (150 g), and 98% sodium nitrite (10 g) to a cold solution of dimethyl malonate (20 g) in ethanol (100 g), followed by saturated aqueous sodium acetate solution slowly to incipient turbidity. The hydrazone crystallized during 24 hours storage in a refrigerator and had m.p. 62° after recrystallization from ethanol. 

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