Oxalic acid is a metabolite of organisms, widely distributed in plants, animals and fungi, and plays different roles in different life forms. It is found that 100 plants are rich in oxalic acid, especially spinach, amaranth, beet, purslane, taro, sweet potato and rhubarb. Oxalic acid can reduce the bioavailability of mineral elements, and easily form calcium oxalate with calcium ions in human body, leading to kidney calculi, so oxalic acid is often considered as an antagonist for the absorption and utilization of mineral elements.
Industrial production method
Carbonyl synthesis method
Carbon monoxide is purified to more than 90%, and reacts with butanol in the presence of palladium catalyst to produce dibutyl oxalate, and then hydrolyzed to obtain oxalic acid. This method can be divided into two types: liquid phase method and gas phase method. The reaction conditions of gas phase method are low, and the reaction pressure is 300-400kPa. The reaction pressure of liquid phase method is 13. 0- 15。 0 MPa.
Sodium formate method
Purified carbon monoxide reacts with sodium hydroxide under pressure to generate sodium formate, then dehydrogenates at high temperature to generate sodium oxalate, and then leads (or calcifies), acidifies, crystallizes, dehydrates and dries the sodium oxalate to obtain the finished product oxalic acid. The synthesis pressure of carbon monoxide and sodium hydroxide is generally 1. 8-2。 0 MPa. Dehydrogenation temperature is 400℃.