Oxalic acid is an organic acid that can be found in common foods, especially in vegetables and fruit, but it is mostly found in vegetables. It has 10,000 times more acidity than acetic acid. When it is in the form of a charge, it is called oxalate, which can form complex compounds with other elements leading to its insoluble property, such as calcium oxalate, magnesium oxalate, sodium oxalate, and potassium oxalate.
Oxalic acid can be converted into oxalate salt in both soluble and insoluble conditions. It can be accumulated in the body in the form of calcium oxalate and other forms that the body can use less.
Physical and Chemical Properties
IUPAC name : Ethanedionic acid
Trade name : Ethanedionic acid, Dicarboxylic acid
Chemical name : Oxalic acid
Chemical group : Carboxylic acid, Aliphatic
Molecular formula : C2H2O4, H-O2-C-C-O2-H
Molecular Weight : 90.04 g/mol
Appearance : Powder
Color : White
Odor : Odourless
Crystal structure : Monoclinic, Rhombic Hygroscopic
Melting point : 90 °C
Boiling point : 149-160 °C
CAS Number : 144-62-7
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Reaction of oxalic acid
2C2H2O4 (aq) + 4H2O (l) = 2C2O4 2- (aq) + 4H2O (aq)
Sources of oxalic acid
It can be synthesized by the body from the metabolic process of ascorbic acid and glyoxylic. Therefore, if the body gets an excessive amount of vitamin C, the amount of oxalic acid may increase.
It comes from food, especially fruits and vegetables with oxalic acid. It is found that vegetables and fruits with much oxalic acid include wild betel leafbushes, paprika, spinaches, cassavas and carrots, etc., It found in sodium or potassium salt form.
Benefits of oxalic acid
Oxalic acid is an acid that is harmful to the human body. However, it can be used in many applications, such as:
• A component of antiseptic solutions
• A component of cleaning solutions
• A chemical additive to kill germs in the wastewater treatment system
• A component of pesticides
• An abrasive or cleaning substance, such as bleaching a straw hat, cleaning the varnish and dyes, removing the rusts, and cleaning the woods.
Toxicity of oxalic acid
If the body gets an overdose of oxalic acid, it can cause toxicity; for example, 5-15 grams can be lethal. If it is given in small amounts and continuously, it can be accumulated in the body by means of precipitation with calcium as calcium oxalate crystals that accumulate in the kidneys, bladder, heart and brain. The more accumulation of calcium oxalate often causes the stone in the urinary tract. If it is accumulated in the brain, it can provide pressure on the nervous system.
Symptoms of acute toxicity when eating vegetables with a high amount of oxalic acid include abdominal pain, intestinal inflammation, vomiting, diarrhea, seizure, blood clotting and even death.
Eating vegetables with a high amount of oxalic acid continuously for a long time often comes with a risk of stone in the bladder. This is in relation to the amount of calcium received from food, namely, the more calcium you receive ; the more you are likely to have the stone in your bladder because the compounds of calcium oxalate can be easily accumulated in the urinary tract.
Oxalic acid is an acid that is highly toxic, corrosive and irritating to the skin and eyes. In addition, it can also have a more severe effect on the body’s internal organs that can irritate and destroy the organs of the digestive and respiratory systems, which can lower the amount of calcium in the body and therefore affects the nervous system. Moreover, it is an important substance that can damage the kidneys.
According to the experiments of giving oxalic acid in mice, the mice’s weight decreased, their growth was slower, Thyroid hormone levels decreased that changes the amount of iodine in their body, working process of calcium in their body decreased, and their reproduction was affected.
Prevention and reduction of toxicity
Prevention of toxicity from oxalic acid includes avoiding or eating in small amounts of vegetables that have high oxalic acid contents as discussed above.
Prevention of toxicity includes eating pumpkin seeds, phosphorus supplements or foods that contain high phosphorus contents, which can reduce the formation of calcium oxalate crystals as well as reduce the amount of crystals in various areas with its accumulation.