2.3- Dihydroxymaleic acid

Rea.ctlons, When free (R-R, R -tartaric acid (4) is heated above its melting point, amorphous anhydrides are formed which, on boiling with water, regenerate the acid. Further heating causes simultaneous formation of pymvic acid, CH COCOOH pyrotartaric acid, HOOCCH2CH(CH2)COOH and, finally, a black, charred residue. In the presence of a ferrous salt and hydrogen peroxide, dihydroxymaleic acid [526-84-1] (7) is formed. Nitrating the acid yields a dinitro ester which, on hydrolysis, is converted to dihydroxytartaric acid [617 8-1] (8), which upon further oxidation yields tartronic acid [80-69-3] (9). 

Precipitation of Fe(IIl) compounds from acid solutions as the pH increases above 2.2 is a particular problem. Complexing agents that have been used include 5-sulfosalicylic acid and citric acid (136) dihydroxymaleic acid (137) ethylenediaminetetraacetic acid (138) lactic acid (138) blends of hydroxylamine hydrochloride, citric acid, and glucono-delta-lactone (139) nitriloacetic acid blends of citric acid and acetic acid lactic acid and gluconic acid (140). 

G. Lundblad, Arkiv Kemi, Mineral. GeoL, 25A, No. 5 (1948) the substance is termed dihydroxymaleic acid in this publication. 

Glycolaldehyde is formed by heating 2 g. of dihydroxymaleic acid in 10 ml. of water until the evolution of carbon dioxide ceases. To the resultant solution is added 2 ml. of ethyl acetoacetate followed by 2 ml. of ethyl alcohol and 1 g. of zinc chloride. The mixture is heated for one hour on a steam bath, and the reaction mixture is extracted with benzene. The benzene extract is washed with a concentrated solution of sodium bisulfite, and evaporated, affording an oil which is saponified by heating with sodium hydroxide solution (10%) on a steam bath for one hour. It is then acidified with dilute hydrochloric acid and extracted with ether. The ethereal extract is dried with anhydrous sodium sulfate and the solvent is evaporated the residue crystallizes from ether m. p., 99°. 

Originally termed dihydroxymaleic acid, which is incorrect.178... 

Chromium(II) chloride, 4052 Cyclohexanone oxime, 2452 l,4-Dicyano-2-butene, 2311 Diethyl dicarbonate, 2444 Diethyl sulfate, Iron, Water, 1710 (Difluoroamino)difluoroacetonitrile, Hydrazine, 0630 Difluoroammonium hexafluoroarsenate, 0098 1,1-Difluorourea, 0398 Dihydroxymaleic acid, 1447 f Diketene, Acids, or Bases, or Sodium acetate, 1441 /V. /V-Dimcthylacctamidc. 1656... 

Acrylic acid, Initiator, Water, 1148 Aluminium chloride, Water, 0062 Barium peroxide, Propane, 0216 1,3-Benzodithiolium perchlorate, 2677 1,1 -Bis(fluorooxy)tetrafluoroethane, 0641 Borane-tetrahydrofuran, 0138 Boron tribromide, Water, 0122 Bromine, Aluminium, Dichloromethane, 0261 Bromine, Tungsten, Tungsten trioxide, 0261 f 1,3-Butadiene, 1480 Calcium oxide, Water, 3937 Chlorine trifluoride, Refractory materials, 3981 Chromium trioxide, Acetic acid, 4242 Copper(II) oxide, Boron, 4281 Diazoacetonitrile, 0675 Dihydroxymaleic acid, 1447 Ethyl azide, 0872... 

Dibromo-l,3-dimethylcyclopropanoic acid, 2364 /V. /V-Dichloroglycinc. 0739 Dilluoroacetic acid, 0702 Dihydroxymaleic acid, 1447... 

Dihydroxymaleic acid (dihydroxyfumaric acid hydrate) [133-38-0] M 148.1, m 155 (dec). Crystd from water. 

Dihydroxybutanedioic acid, see Tartaric acid, 1540 Dihydroxybutenedioic acid, see Dihydroxymaleic acid, 1443... 

The violet colour is due to the formation of a salt or dihydroxymaleic acid, C02H.C(0H)==C(0H).C02H. 

Tartaric acid (200 g., 1.33 moles) is dissolved in 140 ml. of warm water, and to the cooled solution is added a solution of 5 g. of sodium potassium tartrate in 40 ml. of water. The mixture is cooled to —10°, and a solution of 4 g. of ferrous sulfate in 40 ml. of water is added in one portion. The mixture is stirred vigorously and the temperature is held at —5° while 145 ml. of 30% hydrogen peroxide is added slowly (addition requires 5-6 hours). The reaction mixture is stirred for ah additional 2.5 hours at —5° after completion of the addition. The mixture is allowed to stand for a week in an ice chest, and then the precipitated dihydroxymaleic acid is collected by filtration and dried over phosphorus pentoxide. The product contains some iron salt of dihydroxymaleic acid which gives it a pale yellow color. The yield is 42 g. or 24%. 

A mixture of 37 g. (0.25 mole) of dry dihydroxymaleic acid (p. 121) and 92 ml. of pyridine is agitated and warmed to 50-55°. If complete solution does not take place, the mixture is filtered. The clear filtrate is placed in an apparatus for vacuum distillation using an efficient water pump, and the distillation vessel is placed in a bath at 30-35°. The distillation temperature, initially at 22°, rises to 25-27° as the pyridine is removed, and the bath temperature is raised to complete removal of the pyridine. The bath temperature is then raised to 150°, and the syrupy distillate which comes over is freed of pyridine by being allowed to stand in a vacuum desiccator over concentrated sulfuric acid. The compound crystallizes on seeding and standing overnight, and the solid is triturated with a small amount of acetone and filtered. The yield of glycolic aldehyde is 9 g., or 75%. 

The well-known Ruff degradation of aldonic acids to aldoses with one less carbon was first applied with bromine as the oxidant. Calcium D-gluconate was treated with an excess of bromine at 20° for ten hours the acidity of the solution was kept low with lead carbonate. The filtrate was processed and D-arabinose was obtained in small yield as the oxime. However, Ruff found that the effect of hydrogen peroxide was much better and abandoned the use of bromine. Fenton noted the same effect in the oxidation of tartaric acid to dihydroxymaleic acid the action of oxygen was more effective than that of the halogens. It was assumed that a keto aldonic acid was the intermediate in the degradation of the aldonic acid to the new aldose, and the apparent stability of the keto acids to further oxidation by bromine may be the reason for the low yields with this oxidant. 

The ammonium or sodium salt of dihydroxymaleic acid with strong aqueous ammonia at 50-60° for 0.5 hours has been shown to give 2,5-dicarboxypyrazine (278) and a mixture of 23-dihydroxybutane and ammonia over a catalyst of silica gel or alumina at 100-400° gave tetramethylpyrazine (279). 

Udenfriend et al developed a system for effecting aromatic hydroxylation consisting of ferrous sulfate, oxygen, ascorbic acid, and ethylenediaminetetraacetic acid (EDTA) in a phosphate buffer and noted that, in the cases tried, oxygen could be replaced by hydrogen peroxide in a nitrogen atmosphere. EOT A is not essential but greatly increases the reaction rate. Dihydroxymaleic acid and diethyl diketosuccinate were about as active as ascorbic acid alloxan and ninhydrin were less active. Examples ... 

---