4,4'-Methylenedianiline
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4,4′-Methylenedianiline (MDA) is an organic compound with the formula . It is a colorless solid, although commercial samples can appear yellow or brown. It is produced on an industrial scale, mainly as a precursor to
polyurethane Polyurethane (; often abbreviated PUR and PU) is a class of polymers composed of organic chemistry, organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane term ...
s.


Synthesis and applications

In the industrial production, MDA is produced by reaction of formaldehyde and
aniline Aniline (From , meaning ' indigo shrub', and ''-ine'' indicating a derived substance) is an organic compound with the formula . Consisting of a phenyl group () attached to an amino group (), aniline is the simplest aromatic amine. It is an in ...
in the presence of
hydrochloric acid Hydrochloric acid, also known as muriatic acid or spirits of salt, is an aqueous solution of hydrogen chloride (HCl). It is a colorless solution with a distinctive pungency, pungent smell. It is classified as a acid strength, strong acid. It is ...
. MDA is a common monomer in the synthesis of polymer materials. These include polyamides, polyimides and polyimines. MDA is also used extensively as a precursor to methylene diphenyl diisocyanate (MDI). Here, MDA is treated with
phosgene Phosgene is an organic chemical compound with the formula . It is a toxic, colorless gas; in low concentrations, its musty odor resembles that of freshly cut hay or grass. It can be thought of chemically as the double acyl chloride analog of ...
to produce MDI. MDI, in turn, is a precursor to many
polyurethane Polyurethane (; often abbreviated PUR and PU) is a class of polymers composed of organic chemistry, organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane term ...
foams. Lower quantities are used as hardeners in epoxy resins and adhesives, as well as in the production of high-performance polymers. Additionally, hydrogenation of MDA can be performed to produce 4,4,diaminodicyclohexylmethane, which is also used in polymer chemistry. MDA can also be applied as a bidentate (bridging) ligand in the formation of metal-coordination complexes.


Safety

MDA is considered a potential occupational carcinogen by the US National Institute for Occupational Safety and Health. The
Occupational Safety and Health Administration The Occupational Safety and Health Administration (OSHA; ) is a regulatory agency of the United States Department of Labor that originally had federal visitorial powers to inspect and examine workplaces. The United States Congress established ...
has set a permissible exposure limit at 0.01 ppm over an eight-hour time-weighted average, and a short-term exposure limit at 0.1 ppm. It is suspected
carcinogen A carcinogen () is any agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and biologic agents such as viruse ...
. It is included in the " substances of very high concern" list of the European Chemicals Agency ( ECHA). The compound was blamed in a mass poisoning in the vicinity of Epping,
Essex Essex ( ) is a Ceremonial counties of England, ceremonial county in the East of England, and one of the home counties. It is bordered by Cambridgeshire and Suffolk to the north, the North Sea to the east, Kent across the Thames Estuary to the ...
, United Kingdom during 1965 during which 84 individuals were poisoned through accidental contamination of flour used to make bread.


Related compounds

* 4,4'-Thiodianiline *
4,4'-Oxydianiline 4,4′-Oxydianiline (ODA) is an organic compound with the chemical formula, formula Oxygen, O(Carbon, C6Hydrogen, H4Nitrogen, NH2)2. It is an ether derivative of aniline. This colourless solid is a useful monomer and Cross-link, cross-linking agent ...
* Dapsone


References


External links

* * * * {{DEFAULTSORT:Methylenedianiline, 4,4'- 4-Aminophenyl compounds IARC Group 2B carcinogens Mass poisoning