4,4'-Methylenedianiline Explained

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 polyurethanes.

Synthesis and applications

In the industrial production, MDA is produced by reaction of formaldehyde and aniline in the presence of hydrochloric acid.^[1]

MDA is a common monomer in the synthesis of polymer materials. These include polyamides,^[2] polyimides and polyimines.^[3] MDA is also used extensively as a precursor to Methylene diphenyl diisocyanate (MDI). 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.^[4]

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.^[5]

It is suspected carcinogen.^[6] It is included in the "substances of very high concern" list of the European Chemicals Agency (ECHA).^[7] 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.^[8]

Related compounds

• 4,4'-Thiodianiline
• 4,4'-Oxydianiline
• Dapsone

External links

• Web site: International Labour Organization . icsc1111 .
• Web site: Centers for Disease Control and Prevention . NIOSH Pocket Guide to Chemical Hazards .
• Web site: European Union Risk Assessment Report . https://web.archive.org/web/20070317063316/http://ecb.jrc.it/DOCUMENTS/Existing-Chemicals/RISK_ASSESSMENT/REPORT/mdareport008.pdf . 2007-03-17 .
• Web site: Petersen JH, Mortensen SK, Pedersen GA . Memorandum for the Danish Veterinary and Food Administration on . An acute case of primary aromatic amines migrating from cooking utensils . Danish Institute for Food and Veterinary Research . 12 October 2004 .

Notes and References

1. Web site: Data on manufacture, import, export, uses and release of 4-4' diaminodiphenylmethane . https://web.archive.org/web/20111001072741/http://echa.europa.eu/doc/consultations/recommendations/tech_reports/tech_rep_mda.pdf . 2011-10-01 .
2. 10.1021/acsomega.1c06983 . Direct Synthesis of Thermally Stable Semiaromatic Polyamides by Bulk Polymerization Using Aromatic Diamines and Aliphatic Dicarboxylic Acids . Taiki . Endo . Tomoya . Higashihara . ACS Omega . 2022 . 7 . 10 . 8753–8758. free . 35309482 . 8928493 .
3. 10.1021/acs.macromol.2c01595 . Raman Spectroscopy Reveals Phase Separation in Imine-Based Covalent Adaptable Networks . S.K. . Schoustra . M.H.P. . De Heer Kloots . J. . Posthuma . D. . Van Doorn . J.A. . Dijksman . M.M.J. . Smulders . Macromolecules . 2022 . 55 . 23 . 10341–10355 . free . 36530523 . 9753755 . 2022MaMol..5510341S .
4. Encyclopedia: Roose P, Eller K, Henkes E, Rossbacher R, Höke H . Amines, Aliphatic. Ullmann’s Encyclopedia of Industrial Chemistry. 2005. Wiley-VCH. Weinheim. 10.1002/14356007.a02_001. 3-527-30673-0.
5. Web site: 4,4'-Methylenedianiline . NIOSH Pocket Guide on Chemical Hazards .
6. Web site: ToxFAQs for 4,4'-Methylenedianiline . Agency for Toxic Substances and Disease Registry .
7. Web site: Background document for 4,4'-Diaminodiphenylmethane (MDA) . European Chemicals Agency . 2015-02-24 . 2017-08-22 . https://web.archive.org/web/20170822174713/https://echa.europa.eu/documents/10162/13640/mda_en.pdf . dead .
8. Kopelman H, Robertson MH, Sanders PG, Ash I . The Epping jaundice . British Medical Journal . 1 . 5486 . 514–6 . February 1966 . 5902696 . 1843808 . 10.1136/bmj.1.5486.514 .