raw material Oxalic acid

Oxalic Acid More Info

Oxalic Acid is a simple dicarboxylic acid with significant industrial and biological relevance.

Key Basic Information

CAS Number: 144-62-7

Molecular Formula: C₂H₂O₄

Molecular Weight: 90.03 g/mol

Chemical Structure: HOOC-COOH

Physical Properties:

Colorless, crystalline solid

Soluble in water, ethanol, and diethyl ether

Dihydrate form (C₂H₂O₄·2H₂O) is common in nature and industry

Occurrence

Oxalic acid is widely distributed in nature. It is found in many plants, including spinach, rhubarb, sorrel, and cocoa. In these organisms, it often exists as calcium oxalate, an insoluble salt that serves as a storage form of calcium and a defense mechanism against herbivores. It can also be produced by certain fungi and bacteria.

Production Methods

Industrial Synthesis: The most common industrial method is the oxidation of carbohydrates (e.g., glucose, sucrose) using nitric acid, with vanadium pentoxide as a catalyst. Another method involves the hydrolysis of sodium oxalate, which is obtained from the reaction of sodium formate with carbon monoxide.

Laboratory Preparation: Can be prepared by the oxidation of oxalic acid derivatives or the hydrolysis of cyanogen compounds.

Applications

Industrial Cleaning: A strong reducing agent and chelating agent, used for removing rust, scale, and mineral deposits from metal surfaces, boilers, and heat exchangers. It is particularly effective for cleaning stainless steel and aluminum.

Textile Industry: Used as a mordant in dyeing processes to help dyes adhere to textile fibers. Also used in the bleaching of pulp and paper.

Chemical Synthesis: A key intermediate in the production of various chemicals, including oxalates, oxamic acid, and certain pharmaceuticals. It is also used in the synthesis of coordination compounds.

Analytical Chemistry: Used as a standard reagent in titrations, especially for the determination of calcium and other metal ions.

Agriculture: Occasionally used as a herbicide and a plant growth regulator, though its use is limited due to potential toxicity.

Safety and Toxicity

Oxalic acid is toxic to humans and animals if ingested in large quantities. It can react with calcium ions in the body to form insoluble calcium oxalate, which can cause kidney stones and damage to the kidneys and other organs.

It is a strong irritant to the skin, eyes, and respiratory tract. Contact can cause burns and inflammation.

Proper protective equipment (gloves, goggles, respirator) should be worn when handling oxalic acid.

Storage and Handling

Store in a cool, dry, well-ventilated area, away from incompatible substances such as strong oxidizers, strong bases, and metals.

Keep containers tightly closed to prevent moisture absorption and contamination.