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CCl2 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 C6H5NCCl2, either alone or mixed with methylene diaryl isocyanate species,
in o-C6H4Cl2, a
polyurethane process solvent, led to the formation of mixtures containing
dichloro- and trichlorobiphenyl isomers.