formaldehyde

Formaldehyde (systematic name methanal) is an organic compound with the formula and structure . The compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section Forms below). It is stored as aqueous solutions (formalin), which consists mainly of the hydrate CH2(OH)2. It is the simplest of the aldehydes. It is produced commercially as a precursor to many other materials and chemical compounds. In 2006, the global production rate of formaldehyde was estimated at 12 million tons per year. It is mainly used in the production of industrial resins, e.g., for particle board and coatings. Small amounts also occur naturally. Formaldehyde is classified as a carcinogen. Additionally, it can cause respiratory and skin irritation upon exposure. Forms Formaldehyde is more complicated than many simple carbon compounds in that it adopts several diverse forms. These compounds can often be used interchangeably and can be interconverted. Molecular formaldehyde. A colorless gas with a characteristic pungent, irritating odor. It is stable at about 150 °C, but polymerizes when condensed to a liquid. 1,3,5-Trioxane, with the formula (CH2O)3. It is a white solid that dissolves without degradation in organic solvents. It is a trimer of molecular formaldehyde. Paraformaldehyde, with the formula HO(CH2O)nH. It is a white solid that is insoluble in most solvents. Methanediol, with the formula CH2(OH)2. This compound also exists in equilibrium with various oligomers (short polymers), depending on the concentration and temperature. A saturated water solution, of about 40% formaldehyde by volume or 37% by mass, is called "100% formalin". A small amount of stabilizer, such as methanol, is usually added to suppress oxidation and polymerization. A typical commercial-grade formalin may contain 10–12% methanol in addition to various metallic impurities.