HCHO

HCHO is the chemical shorthand for formaldehyde, the simplest member of the aldehyde family. It is a colorless gas at room temperature with a characteristic pungent odor and readily dissolves in water to form formalin, an aqueous solution containing methanediol. The molecule contains a formyl group, giving it high reactivity as a building block in chemical synthesis.

Formaldehyde has a boiling point of −19°C and a melting point of −92°C. It is highly soluble in water and tends to hydrate to methanediol under ambient conditions. In addition to hydration, formaldehyde participates in various polymerization and condensation reactions, forming polymers such as paraformaldehyde and crosslinked resins. It can be oxidized to formic acid or reduced to methanol, illustrating its versatility as an intermediate in industrial chemistry.

Industrial production of formaldehyde mainly involves the catalytic oxidation of methanol with air over a silver-containing catalyst at elevated temperatures. This method yields large quantities of formaldehyde for use in downstream processes. The principal applications are in the manufacture of resins, including urea-formaldehyde, phenol-formaldehyde, and melamine-formaldehyde, which are used in woodworking, textiles, and coatings. Formaldehyde is also employed as a disinfectant, preservative, fixative in histology, and crosslinking agent in various plastics and textiles.

Safety and regulation are important for formaldehyde due to its hazards. It is an irritant to the eyes, skin, and respiratory tract and is classified by the IARC as a Group 1 carcinogen to humans. Exposure is controlled through ventilation, containment, and personal protective equipment, with regulatory limits varying by country. Environmental fate involves relatively rapid oxidation in the atmosphere and biodegradation in water.