Formaldehyde

Formaldehyde ( (listen) fer-mal-duh-hahyd, also (listen) fawr-) (systematic name methanal) is a naturally occurring organic compound with the formula CH2O (H−CHO). The pure compound is a pungent-smelling colourless gas that polymerises spontaneously into paraformaldehyde (refer to section Forms below), hence it is stored as an aqueous solution (formalin). It is the simplest of the aldehydes (R−CHO). The common name of this substance comes from its similarity and relation to formic acid. Formaldehyde is an important precursor to many other materials and chemical compounds.

Synonyms: FORMALIN I Methanal I Oxomethane
Chemical Formula: CH2O
CAS Number: 50-00-0

Characteristics

Melting Point: -15°C

Boiling Point: 97°C

Flash Point: 56 °C

Density: 1.09 g/mL at 25 °C

Uses and Applications

Key applications

Solvents

Industries

General information about Formaldehyde

Formaldehyde is also known as methanal. The gas is one of the most widely produced organic chemicals.

Formaldehyde appears in nature in many different forms. For example, as an intermediate product of metabolism in mammalian cells (including human cells) and bacteria. Formaldehyde is also found in wood and various foods such as apples, grapes, fresh milk (lowest concentration) and hake (highest concentration).

Formaldehyde is the most abundant carbonyl compound in the earth's atmosphere. It is formed during the photochemical reaction of hydrocarbons or the incomplete combustion of fossil fuels and biomass. The combustion of fuel and wood creates atmospheric formaldehyde, with the larger emissions coming from biogenic sources, such as the oxidation of methane and isoprene.

Scientists detected formaldehyde as the first polyatomic organic molecule in many regions of our galaxy. Extraterrestrial formaldehyde is being discussed as a possible source of organic compounds that signalled the origin of life on Earth.

Properties of Formaldehyde

Formaldehyde is a colourless, pungent-smelling gas with the molecular formula CH2O. The organic chemical compound dissolves well in water, ethanol and diethyl ether. The aqueous solution of formaldehyde is called formalin or, more rarely, formol. Formaldehyde is the simplest member of the aldehyde group of substances, as it consists of only one aldehyde group and one hydrogen atom. Formaldehyde is flammable; it ignites at a temperature of 430 degrees Celsius and above. It forms explosive mixtures with air in a concentration range of seven to 73% by volume.

Formaldehyde can be converted into formic acid through oxidation. The IUPAC name formaldehyde is derived from "formica", the Latin word for ant.

Formaldehyde is very reactive. It reacts with itself and other reactants in a series of syntheses to form a variety of products. These reactions include oxidation-reduction reactions, addition or condensation reactions with organic and inorganic substances and self-polymerisation reactions.

Formaldehyde is produced catalytically by oxidation (formox process) or dehydrogenation (silver catalyser process) of methanol. The formox process is the dominant, simpler production method, but the silver process enables the production of higher quality formaldehyde due to a lower formic acid content.

Formaldehyde in the chemical industry

Formaldehyde is one of the most important organic raw materials in the chemical industry and serves as a starting material for many other chemical compounds. The largest market is for urea-formaldehyde resins, which are used as binders for wood-based materials such as chipboard and medium-density fibreboard as well as for the production of glue and adhesives. Urea-formaldehyde resins are also used for impregnating agents and textile finishing agents.

Phenoplastics, polyoxymethylenes and a range of other chemical intermediates such as pentaerythritol and paraformaldehyde, which is used in cell biology, among other things, also have significant market shares.

Melamine-formaldehyde resins are used as impregnating resins, for example to apply decorative paper to laminate flooring or as a component of plastic crockery and cutlery. MF resins are also used in the automotive industry in the form of clear lacquers.

Methylol compounds of formaldehyde and urea, such as methylol urea, which form aminoplasts in the fibre through further condensation, are used in cellulose fibres such as cotton fibres or viscose fibres for textiles. They prevent or reduce creasing of the fabric and increase the dimensional stability of textiles.

Phenol-formaldehyde resins (PF) or phenoplastics are synthetic polymers that are produced with formaldehyde. They are used to produce novolaks, which are used as photoresist materials in microelectronics. They are also used in the production of solid, moulded plastic products such as handles for household and electrical appliances or billiard and skittle balls.

Polyoxymethylene is used in the automotive and electronics industries for technical components such as gear wheels, ball bearings and fastening elements.

Pentaerythritol can be found in plastics, paints, cosmetics and many other applications. It is also used in the production of plasticisers, emulsifiers and explosives such as nitropenta and pentaerythritol trinitrate.

The production of methylene diphenyl isocyanates is also a rapidly growing market for formaldehyde. The main applications are polyurethane foams (e.g. for construction foam and kitchen sponges), paints, adhesives, elastomers and sealants, which are used in the construction industry, for household appliances, shoes and other consumer goods as well as in the automotive industry.

Further areas of application for formaldehyde

Formaldehyde is used in many different areas for disinfection and sterilization. It is available as a 40% solution in water and is used as a fungicide and preservative, for example in the form of formaldehyde releasers in cosmetics. Formaldehyde is also used for room disinfection. It can be nebulized in gaseous form or applied as an aqueous solution. Small medical parts are fumigated with formaldehyde in formaldehyde sterilizers.

In the food industry, fish and meat are given a certain taste in the smoking process and the food is also preserved. Formaldehyde is released during the pyrolysis of hardwoods.

As formaldehyde renders various bacterial toxins and viruses harmless, inactivated vaccines contain CH2O. In livestock farming, formaldehyde is used as a fumigant (in empty stables) to prevent infectious diseases.

Formaldehyde is a protein-crosslinking, additive fixative, i.e. it stops the autolysis and putrefaction of tissue samples and makes them permanently stable. For this reason, it is used in cadaver preservation and the preservation of anatomical and biological specimens.