Formaldehyde is a colorless gas with a pungent odor. It is highly soluble in water and ether, with solutions reaching up to 55% concentration [2]. It can be mixed with solvents like ethanol and acetone in any proportion and is insoluble in petroleum ether. Liquids can become cloudy upon prolonged storage at cooler temperatures and form trioxymethane precipitates at lower temperatures [5]. Some formaldehyde evaporates during the process, but most converts to trioxymethane.

Flammable, obtained in 1859. Molecular weight: 30.03. Relative density: 1.067 (air = 1). Formaldehyde is commonly used in the form of formalin or polymers. Formalin is a water solution with a concentration of 35% to 40% (usually 37%) formaldehyde, where formaldehyde exists in the form of hydrates or oligomers.

Redox property

Formaldehyde is highly reactive in chemistry. Under the catalysis of metals or metal oxides, it is easily reduced to methanol; when oxidized, it can produce formic acid, carbon dioxide, and water. Formaldehyde is a strong reducing agent, and its reductivity is significantly enhanced in trace alkaline conditions. In the air, it can slowly oxidize to formic acid.

Condensation Reaction

Formaldehyde itself can undergo condensation reactions. In general commercial products, 10%-12% of methanol is added as an inhibitor to prevent polymerization. It can react with aldehydes and ketones through alcohol condensation. It readily condenses with amines or amine compounds, such as reacting with ammonia to form melamine, or condensing with urea to produce dimethylol urea. Formaldehyde can condense with syngas to produce ethylene glycol. Redox properties.

Formaldehyde is highly reactive chemically. Under the catalytic action of metals or metal oxides, it is easily reduced to methanol; upon oxidation, it can form formic acid or carbon dioxide and water. Formaldehyde is a strong reducing agent, with an exceptionally strong reductivity in trace amounts of alkalinity, and it can slowly oxidize into formic acid in the air.

Condensation Reaction

Formaldehyde can undergo condensation reactions on its own. In general commodities, 10%-12% of methanol is added as an inhibitor to prevent polymerization. It can react with aldehydes and ketones through an aldol condensation. It readily condenses with amines or amine compounds, such as reacting with ammonia to form melamine, or condensing with urea to produce dimethylol urea. Formaldehyde can condense with syngas to produce ethylene glycol.

Chronic Toxicity

Long-term exposure to formaldehyde can impair respiratory function, the integration of information in the nervous system, and the body's response, and has toxic effects on the cardiovascular, endocrine, digestive, reproductive systems, and kidneys. General symptoms include headaches, fatigue, loss of appetite, palpitations, insomnia, weight loss, and autonomic nervous system disorders. Animal experiments also confirm the pathological changes in the aforementioned systems.

To Mutation

Formaldehyde can cause mutations in Salmonella typhimurium and Escherichia coli regardless of the presence of a metabolic activation system. Continuous dynamic exposure of mice to formaldehyde at concentrations of 0.5mg/m³, 1.0mg/m³, and 3.0mg/m³ for 72 hours significantly increased the micro-nucleus rate of bone marrow polychromatophilic erythrocytes.

Carcinogenicity