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.

苯基二氯异氰（phenyl isocyanide dichloride）与4-甲基苯基二氯异氰可作为特定聚氨酯生产链后期阶段可能生成的副产物的模型化合物。采用自旋捕获剂N-叔丁基-α-苯基硝酮（N-tert-butyl-α-phenylnitrone）的光化学电子顺磁共振（photochemical electron paramagnetic resonance, EPR）研究（照射波长λ>310nm）证实了此前提出的观点：ArN=CCl₂可作为氯自由基源。辐照过程中及辐照后记录的电子顺磁共振光谱经模拟验证后随时间演变，结果表明生成了短寿命的自旋捕获剂-氯自由基加合物以及长寿命的苯甲酰基-N-叔丁基硝酰自由基。在聚氨酯生产工艺溶剂邻二氯苯（o-C₆H₄Cl₂）中，对单独存在或与亚甲基二芳基异氰酸酯类物质混合的C₆H₅N=CCl₂进行光解，可得到含二氯联苯与三氯联苯异构体的混合物。