CH2O

CH2O is the chemical formula for formaldehyde, the simplest aldehyde. It is a colorless gas with a pungent, penetrating odor at room temperature and is often sold or stored as formalin, an aqueous solution containing about 37% formaldehyde.

In structure, CH2O consists of a carbonyl group (C=O) bonded to two hydrogens. The carbon is sp2-hybridized, and the molecule is roughly planar. Formaldehyde is highly soluble in water and is highly reactive as an electrophile. It can polymerize under certain conditions to form polyoxymethylene and related oligomers.

Industrial production of formaldehyde is mainly by catalytic oxidation of methanol over a silver-containing catalyst, yielding formaldehyde in the gas phase, which is then absorbed in water to make solutions. Methanol for this process is typically derived from natural gas or other hydrocarbons. Formaldehyde also occurs in trace amounts in the environment and can be produced by various combustion processes and metabolic pathways in living organisms.

Uses of CH2O include being a fundamental building block in the manufacture of resins such as urea–formaldehyde and phenol–formaldehyde resins, which are used in wood products, textiles, and coatings. It serves as a disinfectant and preservative in laboratories and medicine, notably in the form of formalin for tissue fixation, and functions as an intermediate in numerous chemical syntheses.

Safety and regulation: Formaldehyde is toxic and classified as a human carcinogen. Exposure can irritate the eyes, nose, and throat and may cause sensitization. It is subject to occupational exposure limits and requires appropriate engineering controls, ventilation, and personal protective equipment.