David C. Phillips

The microdetection of particulates from organometallic compounds: I. Metal acetylacetonate chelates

Abstract The new technique of organic particulate analysis (OPA) has been employed to evaluate the thermal decomposition of metal acetylacetonate chelates. Of the 23 compounds thus evaluated, 13 were found to give organoparticulation signals at temperatures In an attempt to characterize the nature of the particulates derived from these compounds, mass-spectral data were obtained on the effluent species arising from the thermal decompositions of the strongest particulate emitting metal acetylacetonates. The results showed that acetylacetone was the major component identified in both particulate and vapor effluents. With the exception of Cr(III) acetylacetonate, no metal was detected in these effluents. The OPA technique enabled the relative thermal stabilities of the metal acetylacetonates to be ascertained. Zn acetylacetonate was found to have the lowest thermal stability and the alkaline earth compounds the highest; the transition metal acetylacetonates exhibit intermediate thermal stabilities. Since a certain critical minimum particulate size (i.e., 25 A) seems to be necessary to produce a response on the ion chamber detector instrument, vapor-phase association of acetylacetone molecules may be occurring. This association would most probably occur through H-bonded species involving the enol form of the 1,3-diketone.

The microdetection of organoparticulates from diazonium compounds

Abstract 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.

Organoparticulate analysis of amine arenesulfonates

INTRODUCTION Previous publications in this area have described the adaptation of the new technique of organoparticulate analysis (6) (OPA), using ion chamber and condensation nuclei instrumentation, to investigate the thermal decomposition of various malonic acids (10) metal acetylacetonates (7), and diazonium compounds (8,9). We would now like to report the investigation of various areneand heterocyclic sulfonic acids and their amine salt derivatives using the same technique.

The Organic Particulate Thermal Analysis of Dithiocarbamate, Isocyanate and Cyanoethylated Compounds

Abstract The technique of Organic Particulate Thermal Analysis (OPTA) has been employed to investigate the thermal decomposition of a series of dithiocarbamate, isocyanate and cyanoethylated compounds; OPTA measures the temperature at which particulate or aerosol matter is emitted from a heated organic substance. Of the 22 compounds investigated, 15 showed strong organoparticulation activity below 200°C. With the possible exception of three compounds, no obvious correlation exists between the OPTA values and the melting or decomposition point of the compound. To explain the organoparticulation activity of these compounds, the hydrogen-bonding of polar, molecular species, present in the particulate matter, appeared necessary.