H2CO

H2CO, commonly known as formaldehyde, is the simplest member of the aldehyde family. Its chemical formula CH2O reflects a carbonyl group doubly bonded to oxygen and bonded to two hydrogens. Formaldehyde is a colorless gas at room temperature with a sharp, penetrating odor and is highly soluble in water, where it exists predominantly as formaldehyde or as the formalin solution (about 37% formaldehyde in water).

Industrially, formaldehyde is produced primarily by the catalytic oxidation of methanol over metal catalysts, yielding a mixture that is normally supplied as an aqueous solution. It is a versatile chemical feedstock and a key precursor for resins such as urea-formaldehyde, phenol-formaldehyde, and melamine-formaldehyde resins, which are used in plastics, textiles, coatings, and plywood. Formaldehyde is also employed in embalming, disinfection, and as a fixative for biological specimens in microscopy and histology.

In chemistry, formaldehyde is reactive due to the electrophilic carbonyl carbon. It readily polymerizes to polyoxymethylene (paraformaldehyde) and participates in formylation and hydroxymethylation reactions, enabling a wide range of synthetic transformations. Its reactivity also underpins its toxicity and irritant properties.

Safety and regulation are central to handling formaldehyde. It is a potent irritant to eyes, skin, and the respiratory tract and is classified as a human carcinogen by several health agencies. Handling requires adequate ventilation, containment, and appropriate personal protective equipment. Environmental and occupational exposure limits vary by jurisdiction.

Detection and analysis of formaldehyde employ methods such as derivatization with DNPH for chromatographic measurement, infrared spectroscopy for gas-phase and solution-phase analysis, and various spectroscopic techniques in research and industry.