How is citric acid prepared? Give its important properties and uses.

citric acid C6H8O7 2 HYDROPROPANE-1,2,3TRICARBOXYLIC ACID It has three carboxyl or -COOH group PROPERTIES OF CITRIC ACID:- Citric acid is the intermediate product of the plants of a natural composition and physiological metabolism, is also one of the organic acids widely used in the field of food, medicine, chemical industry. It is colorless transparent or translucent crystal, or granular, particle powder, odorless, although has strong sour, but a pleasant, slightly astringent taste. In the warm air gradually disintegrate, in the humid air, it is slight deliquescence. (1) Reaction with Acid Citric acid and fuming sulfuric acid mixed, at room temperature, which produce aconitic acid, slightly heating can generate 3 - ketoglutarate. The mixture of citric acid and concentrated sulfuric acid, temperature at 40? into acetone and CO2, CO, etc.; when heated to 150? to generate aconitic acid anhydride; generate double Kang acid (diconic acid) C9H10O6 and CO heating to 200 ?, CO2 and so on. When the sulfate concentration is less than 94%, generating 3- ketoglutaric acid at low temperature; when the sulfate concentration is less than 60%, when heated to generate aconitic acid. Anhydrous citric acid and 1 portions of nitric acid and 2 copies of the action of sulphuric acid form nitric acid ester C3H5 (ONO2) (COOH)3, it does not dissolve in ether, and barium and lead combine to form insoluble salts. (2) Reaction with Alkali The citric acid is fused with K2CO3 or KOH or nitric acid to obtain oxalic acid and acetic acid or other salts. Citric acid and sodium salt (such as NaCl) lime carbonization to yield acetone. Citric acid is get boiling in alkaline solution to obtain acrylic acid (C3H4O2). The conventional acid base neutralization reaction of citric acid can produce various kinds of salts. (3) the effect of Glycerol Citric acid and glycerol mixed by dry distillation to obtain acetone, CO, CO2 and glycerol in the ether acetone acid ester. The mixture of citric acid and glycerol are heated to 100 ?, and generate citric acid ester of glycerol , which is substance like glass. If large amount of glycerol and heated to 170? to get citronella diglycerol( citrodiglycerin C12H18O11). Citric acid and glycerin which is according to the molar ratio of 1:3 heat can be citric acid glyceride. With different molar ratio of which can obtain different properties of resinous substance, and some were gel or solid form, some do not dissolve in water, some solution in water. If tung oil or oil and stearic acid are heated to 100?, can shrink synthetic resinous substance, it is used as paint and plastics additives or special solvent. USES:- 1. Food Industries 2.Metal Purification 3. Used as a reagent 4.Ideal substitute for phosphate read less