INVESTIGATION OF THE POLYMERIZATION OF 1,4-DINITROSOBENZENE BY LOW-TEMPERATURE INFRARED AND UV ABSORPTION-SPECTROSCOPY

Warming poly(1,4-phenyleneazine NN-dioxide) at 50-65-degrees-C and dep ositing under vacuum onto a CsI window at cryogenic temperatures gives 1,4-dinitrosobenzene, identified from infrared bands around 1520,1120 ,850,and 780 cm-1, which are characteristic for aromatic C-nitroso com pounds. Thin films of 1,4-dinitrosobenzene were warmed from 32 K to ro om temperature in vacuo, and the polymerization reaction was shown to proceed through an intermediate, stable from 180 to 220 K. The interme diate shows C-nitroso- vibrational frequencies similar to those of the monomer but also has a strong band at 1260 cm-1 typical for an O-N=N- O vibration in its infrared spectrum, assigned to the trans dimer of 1 ,4-dinitrosobenzene. Further warming of these films above 220 K result s in formation of oligomers, and finally at temperatures from ca. 260 K to room temperature, complete polymerization occurs to regenerate po ly(1,4-phenyleneazine N,N-dioxide). Similar results were obtained from UV absorption spectroscopy, which detected formation of an intermedia te at ca. 180 K that on further warming to room temperature gave the p olymer.