4,4'-Methylenedianiline

4,4′-Methylenedianiline (MDA) is an organic compound with the formula CH2(C6H4NH2)2. 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.

4,4′-Methylenedianiline
Names
Preferred IUPAC name
4,4′-Methylenedianiline
Other names
4,4′-Diaminodiphenylmethane; 4,4′-Methylenebisbenzenamine; MDA; para,para′-Diaminodiphenylmethane; Dianilinomethane; 4,4′-Diphenylmethanediamine; Bis(4-aminophenyl)methane
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.002.705
EC Number
  • 202-974-4
KEGG
RTECS number
  • BY5425000
UNII
UN number 2651
  • InChI=1S/C13H14N2/c14-12-5-1-10(2-6-12)9-11-3-7-13(15)8-4-11/h1-8H,9,14-15H2 ☒N
    Key: YBRVSVVVWCFQMG-UHFFFAOYSA-N ☒N
  • InChI=1/C13H14N2/c14-12-5-1-10(2-6-12)9-11-3-7-13(15)8-4-11/h1-8H,9,14-15H2
    Key: YBRVSVVVWCFQMG-UHFFFAOYAE
  • c1cc(N)ccc1Cc2ccc(N)cc2
Properties
C13H14N2
Molar mass 198.269 g·mol−1
Appearance Colorless solid
Odor faint, amine-like[1]
Density 1.05 g/cm3 (100°C)
Melting point 89 °C (192 °F; 362 K)
Boiling point 398 to 399 °C (748 to 750 °F; 671 to 672 K)
0.125 g/100 ml (20 °C)
Vapor pressure 0.0000002 mmHg (20°C)[1]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 potential carcinogen[1]
GHS labelling:
GHS08: Health hazard GHS07: Exclamation mark GHS09: Environmental hazard
Danger
H317, H341, H350, H370, H373, H411[2]
P201, P260, P273, P280, P308+P313[2]
Flash point 190 °C; 374 °F; 463 K[1]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 0.010 ppm ST 0.100 ppm[1]
REL (Recommended)
 Ca[1]
IDLH (Immediate danger)
 Ca [N.D.][1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Synthesis and applications

In the industrial production, MDA is produced by reaction of formaldehyde and aniline in the presence of hydrochloric acid.[3]

MDA is a common monomer in the synthesis of polymer materials. These include polyamides,[4] polyimides and polyimines.[5] 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.[6][7] Lower quantities are used as hardeners in epoxy resins and adhesives, as well as in the production of high-performance polymers.[3] Additionally, hydrogenation of MDA can be performed to produce 4,4,diaminodicyclohexylmethane, which is also used in polymer chemistry.[8]

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.[9]

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.[10]

References
  1. NIOSH Pocket Guide to Chemical Hazards. "#0415". National Institute for Occupational Safety and Health (NIOSH).
  2. Record of 4,4'-Diaminodiphenylmethane in the GESTIS Substance Database of the Institute for Occupational Safety and Health, accessed on 12 February 2021.
  3. "Data on manufacture, import, export, uses and release of 4-4' diaminodiphenylmethane" (PDF). Archived from the original (PDF) on 2011-10-01.
  4. Endo, Taiki; Higashihara, Tomoya (2022). "Direct Synthesis of Thermally Stable Semiaromatic Polyamides by Bulk Polymerization Using Aromatic Diamines and Aliphatic Dicarboxylic Acids". ACS Omega. 7 (10): 8753–8758. doi:10.1021/acsomega.1c06983.
  5. Schoustra, S.K.; De Heer Kloots, M.H.P.; Posthuma, J.; Van Doorn, D.; Dijksman, J.A.; Smulders, M.M.J. (2022). "Raman Spectroscopy Reveals Phase Separation in Imine-Based Covalent Adaptable Networks". Macromolecules. 55 (23): 10341–10355. doi:10.1021/acs.macromol.2c01595.
  6. "ToxFAQs for 4,4'-Methylenedianiline". Agency for Toxic Substances and Disease Registry.
  7. "Background document for 4,4'-Diaminodiphenylmethane (MDA)" (PDF). European Chemicals Agency.
  8. Roose P, Eller K, Henkes E, Rossbacher R, Höke H (2005). "Amines, Aliphatic". Ullmann’s Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a02_001. ISBN 3527306730.
  9. "4,4'-Methylenedianiline". NIOSH Pocket Guide on Chemical Hazards.
  10. Kopelman H, Robertson MH, Sanders PG, Ash I (February 1966). "The Epping jaundice". British Medical Journal. 1 (5486): 514–6. doi:10.1136/bmj.1.5486.514. PMC 1843808. PMID 5902696.
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