What is Oxalic Acid?

Everyone knows about the incompatibility of foods. Some foods are fine when eaten alone, but if eaten with other foods, they will often cause certain harm to the body. In severe cases, they can even cause poisoning and endanger life. For example, persimmons and crabs will cause poisoning if eaten together. In addition to food incompatibility, some foods are inherently toxic or contain toxic substances, for example, many foods contain oxalic acid.

In fact, scientifically speaking, oxalic acid is a chemical substance. Oxalic acid is widely distributed in nature. It often exists in the form of oxalate in some plants, such as spinach. Of course, in addition to being toxic to the human body, oxalic acid also has a huge effect. So, what exactly is oxalic acid?

Oxalic acid, also known as oxalic acid, is one of the simplest organic dibasic acids. The structural formula is HOOCCOOH. It is generally colorless and transparent crystals, which are harmful to the human body. It will cause the acid-base balance in the human body to lose balance and affect the development of children. Oxalic acid plays an important role in industry and can remove rust.

Colorless monoclinic flakes or prismatic crystals or white powder. Oxidized oxalic acid is odorless, while synthetic oxalic acid has an odor. Sublimation at 150-160℃. Can weather in hot and dry air. 1g is soluble in 7ml water, 2ml boiling water, 2.5ml ethanol, 1.8ml boiling ethanol, 100ml ether, 5.5ml glycerol; it is insoluble in benzene, chloroform and petroleum ether. The pH value of 0.1 mol/L solution is 1.3. Relative density (d18.54) 1.653. Melting point 101～102℃ (187℃, anhydrous). Low toxicity, median lethal dose (rabbit, percutaneous) 2000 mg/kg.

Oxalic acid is a common component in plants, especially herbal plants, and mostly exists in the form of potassium salt or calcium salt. It exists in the form of free acid in begonia and plantain.

Oxalic acid has a wide range of uses and is generally used in analysis to detect and determine metal ions such as beryllium, calcium, chromium, gold, manganese, strontium, and thorium. Microscopic microcrystal analysis tests for sodium and other elements. Precipitates calcium, magnesium, thorium and rare earth elements. Calibrate standard solutions of potassium permanganate and cerium sulfate solutions. Bleach. Dyeing aid. It can also be used to remove rust from clothes. In the construction industry, before applying exterior wall paint, oxalic acid should be applied to remove the alkali because the wall surface is highly alkaline.

The pharmaceutical industry uses it to manufacture drugs such as chlortetracycline, oxytetracycline, tetracycline, streptomycin, borneol, vitamin B12, and phenobarbital. In the printing and dyeing industry, it is used as a color developing auxiliary, bleaching agent, and pharmaceutical intermediate. The plastics industry is used to produce polyvinyl chloride, amino plastics, and urea-formaldehyde plastics.

In addition to the above-mentioned role of oxalic acid in society, the most important thing for us ordinary people is that it is toxic to the body. Because almost all plants contain oxalic acid, and many of them are eaten by humans. Oxalic acid is not easily digested by the human body after being eaten, and it is highly acidic and very bad for the stomach. Eating too much can easily lead to poisoning. Therefore, in our daily lives, we should try to avoid eating foods containing oxalic acid.