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formaldehyde(fôrmăl`dəhīd'), HCHO, the simplest aldehydealdehyde
[alcohol + New Lat. dehydrogenatus=dehydrogenated], any of a class of organic compounds that contain the carbonyl group, , and in which the carbonyl group is bonded to at least one hydrogen; the general formula for an aldehyde is RCHO, where R is hydrogen
..... Click the link for more information. . It melts at −92°C;, boils at −21°C;, and is soluble in water, alcohol, and ether; at STPSTP
or standard temperature and pressure,
standard conditions for measurement of the properties of matter. The standard temperature is the freezing point of pure water, 0°C; or 273.15°K;.
..... Click the link for more information. , it is a flammable, poisonous, colorless gas with a suffocating odor. Formaldehyde is used in the preparation of dyes, in the production of BakeliteBakelite
[for its inventor, L. H. Baekeland], synthetic thermosetting resin. It has been widely used both alone, to form whole objects, and in combination with other materials, as a laminate or a surface coating.
..... Click the link for more information. and other plastics and synthetic resins, and for several other purposes, such as in glues and adhesives used to produce laminated and composite woods and wood products. Pure gaseous formaldehyde is uncommon, since it readily polymerizes into paraformaldehyde, a white crystalline solid. Paraformaldehyde in the form of candles has been used for fumigating rooms, since it yields formaldehyde when heated. Formalin is a 40% by volume solution of formaldehyde in water, usually with a small amount of methanol (methyl alcohol) added to prevent polymerization; it is used as an antiseptic, disinfectant, and preservative for biological materials. Formaldehyde is prepared commercially by passing methanol vapor mixed with air over a catalyst, e.g., hot copper, to cause oxidation of the methanol; it is also prepared by the oxidation of natural gas. It forms formic acid when it is oxidized. The IUPAC name for formaldehyde is methanal.
(also methanal), CH2O, the first member of the homologous series of aliphatic aldehydes. A colorless gas with a pungent odor, formaldehyde is freely soluble in water and alcohol. It has a boiling point of – 19°C.
Formaldehyde is prepared commercially by the oxidation of methanol (methyl alcohol) or methane with atmospheric oxygen. Because it polymerizes readily, especially at temperatures up to 100°C, it is stored, transported, and used mainly in the form of Formalin or in the form of solid low-molecular polymers— trioxane and paraformaldehyde.
Formaldehyde is highly reactive. Many of its reactions form the basis of numerous commercial methods for the preparation of important products. For example, on interaction with ammonia, formaldehyde yields urotropine (hexamethylenetetramine); with urea, urea-formaldehyde resins; with melamine, melamine resins; with phenols, phenol-formaldehyde resins; with phenol-sul-fonic and napthalene sulfonic acids, tanning agents; and with ket-ene, beta-propiolactone. Formaldehyde is used in the manufacture of polyvinyl formal, isoprene, pentaerythritol, pharmaceuticals, and dyes. It is also used in the tanning of leather and as a disinfectant and deodorizing agent. The polymerization of formaldehyde yields polyformaldehyde.
Formaldehyde is toxic; its maximum tolerable concentration in the air is 0.001 mg/liter.