Origin of impurities formed in the polyurethane production chain. 1. Conditions for chlorine transfer from an aryl isocyanide dichloride byproduct

Phenyl and 4-methylphenyl isocyanide dichlorides are models for byproduct that may be formed in the later stages of certain polyurethane production chains. Photochemical electron paramagnetic resonance (EPR) studies (λ > 310 nm), using the spin trap, N-tert-butyl-α-phenylnitrone, confirm a previously made suggestion that ArN=CCl 2 can behave as a chlorine radical source. EPR spectra recorded during and after irradiation and supported by simulations evolve over time and indicate formation of the short-lived spin trap-Cl • adduct and a longer lived benzoyl-N-tert-butylnitroxide radical. Photolysis of C 6H 5N=CCl 2, either alone or mixed with methylene diaryl isocyanate species, in o-C 6H 4Cl 2, a polyurethane process solvent, led to the formation of mixtures containing dichloro- and trichlorobiphenyl isomers. © 2011 American Chemical Society.