4,4'-Methylenedianiline
4,4′-Methylenedianiline 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 polyurethanes.
Synthesis and applications
In the industrial production, MDA is produced by reaction of formaldehyde and aniline in the presence of hydrochloric acid.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. Here, MDA is treated with phosgene to produce MDI. MDI, in turn, is a precursor to many polyurethane 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 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 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. It is included in the "substances of very high concern" list of the European Chemicals Agency. The compound was blamed in a mass poisoning in the vicinity of Epping, Essex, United Kingdom during 1965 during which 84 individuals were poisoned through accidental contamination of flour used to make bread.