Flash-vacuum Pyrolysis of 1-Acylbenzotriazole: Direct Observation of Cyclopenta-2,4-dienylidenemethaneimines by Tandem Mass Spectrometry and Low-temperature Infrared Spectrometry

Article abstract of DOI:10.1002/oms.1210250404

A real-time analysis of the flash-vacuum pyrolysis products of 1-acetylbenzotriazole (1) and 1-benzoylbenzotriazole (2) was performed by tandem mass spectrometry.In the temperature range 500-600 deg C, these compounds lose nitrogen, yielding N-acetyl- and N-benzoylcyclopenta-2,4-dienylidenemethaneimines (10 and 17, respectively).At higher pyrolysis temperatures, 1 gives 2-methylbenzoxazole, cyanocyclopentadiene, methylcyanocyclopentadiene(s), benzonitrile and ketene, which were identified by collision-activated mass spectrometry.Low-temperature infrared experiments confirmed the pyrolytic transformation 1(2) -> 10(17) at mediated temperatures.