A structural and spectroscopic investigation of the hydrochlorination of 4,4-methylenedianiline

Gibson, E.K. , Winfield, J.M., Muir, K.W., Carr, R.H., Eaglesham, A., Gavezzotti, A. and Lennon, D. (2010) A structural and spectroscopic investigation of the hydrochlorination of 4,4-methylenedianiline. Physical Chemistry Chemical Physics, 12(15), pp. 3824-3833. (doi: 10.1039/b916368a)

Abstract

The hydrochlorination of 4,4-methylenedianiline, NH2C6H4CH2C6H4NH2 (MDA), in chlorobenzene to produce 4,4-methylenedianiline dihydrochloride, [H3NC6H4CH2C6H4NH3]Cl2 (MDA·2HCl) is an important reaction for the production of isocyanates, which are used to manufacture polyurethanes. This reaction is examined here. MDA is moderately soluble in chlorobenzene, whereas MDA·2HCl is effectively insoluble. Controlled addition of anhydrous HCl to MDA in chlorobenzene led to the isolation of a solid whose stoichiometry is MDA·HCl. Crystals obtained from solutions of MDA·HCl in methanol were found by X-ray analysis to consist of the basic hydrochloride salt, [MDAH2][Cl]2[MDA]2H2O, which is stabilised by complex hydrogen-bonding. The starting material MDA has an H-bonded structure in which the molecules are linked in a one-dimensional chain. Hydrogen-bonding is extensive in MDA·2HCl which contains ladders of [H3NC6H4CH2C6H4NH3]2+ dications stabilised by N–HCl linkages. Energy calculations on the crystalline systems allow an identification of the main factors in intermolecular cohesion; these are related to melting temperature and solubility data. Such improvements in understanding of solute–solute interactions are prerequisites for improving the atom economy of this important stage within the polyurethane manufacture process chain. The solid phase IR spectrum of MDA·2HCl is diagnostic, principally as a result of a Fermi resonance process.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Winfield, Professor John and Muir, Dr Kenneth and Lennon, Professor David and Gibson, Dr Emma
• Authors: Gibson, E.K., Winfield, J.M., Muir, K.W., Carr, R.H., Eaglesham, A., Gavezzotti, A., and Lennon, D.
• Subjects: Q Science > QD Chemistry
• College/School: College of Science and Engineering > School of Chemistry
• Journal Name: Physical Chemistry Chemical Physics
• ISSN: 1463-9076
• ISSN (Online): 1463-9084