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

Abstract

The hydrochlorination of 4,4'-methylenedianiline, NH(2)C(6)H(4)CH(2)C(6)H(4)NH(2) (MDA), in chlorobenzene to produce 4,4'-methylenedianiline dihydrochloride, [H(3)NC(6)H(4)CH(2)C(6)H(4)NH(3)]Cl(2) (MDA x 2 HCl) 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 x 2 HCl is effectively insoluble. Controlled addition of anhydrous HCl to MDA in chlorobenzene led to the isolation of a solid whose stoichiometry is MDA x HCl. Crystals obtained from solutions of MDA x HCl in methanol were found by X-ray analysis to consist of the basic hydrochloride salt, [MDAH(2)][Cl](2)[MDA](2)H(2)O, 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 x 2 HCl which contains ladders of [H(3)NC(6)H(4)CH(2)C(6)H(4)NH(3)](2+) dications stabilised by N-H...Cl 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 x 2 HCl is diagnostic, principally as a result of a Fermi resonance process.

Spectroscopic Characterization of Model Compounds, Reactants, and Byproducts Connected with an Isocyanate Production Chain

“…Gibson and co-workers have previously studied the hydrochlorination of 4,4′-methylenedianiline in chlorobenzene, providing a structural and spectroscopic awareness of the formation of the dihydrochloride salt, 4,4′-methylenedianiline dihydrochloride (MDA·2HCl, [H 3 NC 6 H 4 CH 2 C 6 H 4 NH 3 ]­Cl 2 ). In certain circumstances a monohydrochloride salt (MDA·HCl) can be isolated . Earlier work from Gibson et al also investigated the hydrochlorination of 4-benzylaniline (4-BA, C 6 H 4 CH 2 C 6 H 4 NH 2 ) in chlorobenzene .…”

The role of Jahn–Teller distortion in insulator to semiconductor phase transition in organic–inorganic hybrid compound (p-chloroanilinium)2CuCl4at high pressure

“…These modes are related to Fermi resonance processes corresponding to combination bands of R-NH 3 + deformation and rocking modes. 19 A mode at B812 cm À1 corresponding to C-H out of plane deformation shows softening up to B3 GPa and then it hardens up. For these modes, half the carbon atoms bend forward and the remaining backward.…”

“…We could not trace low frequency Cu-Cl stretching infrared vibrational modes due to the limitation of the HgCdTe detector. The assignments of some of the significant modes associated with vibrations of organic salt p-chloroanilinium chloride 18,19 are mentioned in Table 1. Our high pressure FTIR measurements on (PClAnCuCl) as shown in Fig.…”

The interaction of CO with a copper(ii) chloride oxy-chlorination catalyst

“…3 A prominent feedstock is methylene diphenyl diisocyanate (MDI), which is typically made via the reaction of phosgene with 4,4'methylenedianiline. 3 The total global production capacity for MDI in 2010 was 5 million tonnes, 5 with this material often prepared on-site within an integrated chemical complex. With respect to equations 2 and 3, it is seen that 1 mole of phosgene produces 2 moles of HCl and that there is no incorporation of chlorine into the product.…”