Overview
Occurrence
Processes in the upper atmosphere contribute up to 90% of the total formaldehyde in the environment. Formaldehyde is an intermediate in the oxidation (or combustion) of methane, as well as of other carbon compounds, e.g. in forest fires, automobile exhaust, and tobacco smoke. When produced in the atmosphere by the action of sunlight and oxygen on atmospheric methane and other hydrocarbons, it becomes part of smog. Formaldehyde has also been detected in oute…
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 o…
Synthesis and industrial production
Formaldehyde was first reported in 1859 by the Russian chemist Aleksandr Butlerov (1828–86) In his paper, Butlerov referred to formaldehyde as "dioxymethylen" (methylene dioxide) [page 247] because his empirical formula for it was incorrect (C4H4O4). It was conclusively identified by August Wilhelm von Hofmann, who first announced the production of formaldehyde by passing methanol vapor in air over hot platinum wire. With modifications, Hoffmann's method remains th…
Organic chemistry
Formaldehyde is a building block in the synthesis of many other compounds of specialised and industrial significance. It exhibits most of the chemical properties of other aldehydes but is more reactive.
Formaldehyde, unlike most aldehydes, oligomerizes spontaneously. The trimer is 1,3,5-trioxane, and the polymer is called paraformaldehyde. Many cyclic oligomers have been isolated. Similarly…
Uses
Formaldehyde is a common precursor to more complex compounds and materials. In approximate order of decreasing consumption, products generated from formaldehyde include urea formaldehyde resin, melamine resin, phenol formaldehyde resin, polyoxymethylene plastics, 1,4-butanediol, and methylene diphenyl diisocyanate. The textile industry uses formaldehyde-based resins as f…
Safety
In view of its widespread use, toxicity, and volatility, formaldehyde poses a significant danger to human health. In 2011, the US National Toxicology Program described formaldehyde as "known to be a human carcinogen".
However, concerns are associated with chronic (long term) exposure by inhalation as may happen from thermal or chemical decomposition of formalde…
Contaminant in food
Scandals have broken in both the 2005 Indonesia food scare and 2007 Vietnam food scare regarding the addition of formaldehyde to foods to extend shelf life. In 2011, after a four-year absence, Indonesian authorities found foods with formaldehyde being sold in markets in a number of regions across the country. In August 2011, at least at two Carrefour supermarkets, the Central Jakarta Livestock and Fishery Sub-Department found cendol containing 10 parts per million of …