Oxalic acid
Simplest dicarboxylic acid, used in cleaning and metal chelation.
Oxalic acid is an organic acid with the systematic name ethanedioic acid and chemical formula HO−C(=O)−C(=O)−OH. It is the simplest dicarboxylic acid, a white crystalline solid that forms a colorless solution in water. Its name derives from early investigators who isolated it from flowering plants of the genus Oxalis, commonly known as wood-sorrels. It occurs naturally in many foods and can be toxic when ingested in significant quantities, with concentrated forms capable of causing chemical burns.
- chemical_formula
- HO−C(=O)−C(=O)−OH (also H2C2O4)
- type
- Organic acid, simplest dicarboxylic acid
- common_uses
- Cleaning agent, rust removal, lanthanide chemistry
Reader's Guide
Oxalic acid is significant as the simplest dicarboxylic acid and a relatively strong organic acid. It serves as a reducing agent and its conjugate bases are chelating agents for metal cations, making it valuable for rust removal by forming water-soluble ferric iron complexes. Historically, it was obtained from sawdust using caustics. In the laboratory, it can be prepared by oxidizing sucrose with nitric acid and vanadium pentoxide catalyst. Oxalic acid occurs naturally in many foods, including spinach, rhubarb leaves, and starfruit, and is produced by soil fungi. Its biochemistry includes acting as a competitive inhibitor of lactate dehydrogenase, an enzyme important in anaerobic metabolism, which has potential implications for cancer treatment. The compound also plays a key role in interactions between pathogenic fungi and plants, with small amounts enhancing plant resistance but higher amounts causing programmed cell death.
Did You Know?
- Oxalic acid is a much stronger acid than acetic acid.
- It forms a water-soluble ferric iron complex, the ferrioxalate ion, used for rust removal.
- Plants of the genus Fenestraria produce optical fibers made from crystalline oxalic acid to transmit light to subterranean photosynthetic sites.
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