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Molecular formula : C2H2O4
MW : 90.04
CAS No. :144-62-7
nature : oxalic acid generally contain two elements crystalline water, a colorless transparent crystal, the crystal structure of two forms, namely α - (diamond), and β - (monoclinic Crystal), the melting point, respectively, α-type : 189.5 ° C, β - type : 182 ° C The relative density of α : 1.900, β - type : 1.895. Refractive index of 1.540. Oxalic acid in 100 ° Cdistillation of 125 ° C rapid distillation of 157 ° C at large sublimation, and begin to decompose. Soluble in ethanol, dissolved in water, ether-soluble and insoluble benzene and chloroform.
Preparation : oxalic acid found in the natural world, often in the form of oxalate in plants such as Barberry, sheep hoof grass, Oxalis grass and sorrel the cell membrane, and almost all the plants containing calcium oxalate. Oxalate industrialized production methods are : Sodium, oxidation, Oxo, oxidation of ethylene glycol, propylene oxide, carbon monoxide coupling method. 1. Sodium France after the purification of carbon monoxide under pressure and sodium hydroxide reaction Sodium generation, and then generate high temperature dehydrogenation of sodium, sodium via grass of lead (or calcification), acidification, dehydration and drying crystallization processes, to be finished oxalate. Synthesis of carbon monoxide and sodium hydroxide general pressure of 1.8-2.8MPa. Dehydrogenation temperature of 400 ° C. 2. Oxidation of starch to glucose solution or as raw material, alumina in the presence of a catalyst, with nitric acid-sulfuric acid oxidation reaction in oxalic acid. Emissions of nitrogen oxide absorber recovery sent dilute nitric acid production. 3. Oxo law purification of carbon monoxide by 90%, and palladium catalysts in the presence of n-butanol and occurred carbonylation reactions, the formation of oxalic acid dibutyl, then pass the acid hydrolysis be that the law is divided into liquid and gas phase two, Gas Act lower reaction conditions, the pressure is 300 - set 400kPa. While liquid reaction pressure for 13.0 - 15.0MPa. 4. Oxidation glycol ethylene glycol as raw materials to the existence of nitric acid and sulfuric acid, derived using air oxidation. 5. Propylene oxide oxidation process is done in two steps. First step is to use nitrate oxide, propylene conversion of α - nitro-lactic acid; Then be further oxalic acid oxidation. The second step also can be mixed acid as the oxidizing agent. Propylene Oxide Production of industrial compounds oxalate dihydrate, propylene dollars to the total yield of more than 90%. The consumption of raw materials fixed : Coke (84%) 510kg / t, sulfuric acid (100%) 950kg / t, caustic soda (100%) 920kg / t.
purposes : oxalic acid used in the production of antibiotics and other drugs borneol extract rare metals and solvents, dyes reductant, tanning agents. In addition, the oxalic acid can be used for synthesis of various oxalate, oxalate and OXAMIDE products, and to diethyl oxalate and sodium grass, the largest output of calcium oxalate. Oxalic acid can be used cobalt-molybdenum - alumina catalyst production, metal and marble cleaning and bleaching of textiles.
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