The microdetection of organoparticulates from diazonium compounds

The thermal decompositions of a series of diazonium compounds have been investigated using the new technique of organic particulate analyses (OPA). This extremely sensitive technique makes possible the detection of particulates emitted from the diazonium compounds during thermal decomposition. The submicron particulates derived in this fashion are readily detectable by their influence on the output current of an ion chamber detector or by their effect on the cloud chamber of a condensation nuclei monitor.Of the 14 diazonium compounds evaluated, 11 were found to exhibit particulation behavior below 190 °C. In some cases, very strong particulation was detectable. No apparent correlation between the organic particulation temperature range (OPTR) and their literature thermal decomposition temperatures was evident. Efforts were made to characterize the nature of the particulates using mass spectrometry but this was hampered by the extreme complexities of the spectral patterns.In terms of their abilities to produce particulates, the diazonium compounds can be placed in four main groups reflecting their chemical composition, molecular size, and degree of substitution. Vapor phase association of the molecular fragments formed during thermal decomposition might be occurring to produce the required particulate size detectable by the present instrumentation.