LOW-TEMPERATURE MATRIX-ISOLATION INFRARED-SPECTROSCOPY - A METHOD TO CHARACTERIZE REACTIVE SPECIES FROM LOW-PRESSURE PYROLYSIS OF HYDROCARBONS FOR MECHANISTIC ELUCIDATIONS

In organic high-temperature gas-phase chemistry, radical chain processes and simple radical reaction routes are considered to be those which dominate the reaction process and decide essentially on the composition of the product mixtures. The measured radical concentrations, however, are normally so low that they can not be detected directly as individuals on stream. An effective and efficient method for detecting and characterizing radicals which are generated at high temperatures and low pressures in the gas phase is low-temperature matrix-isolation in combination with IR spectroscopy. This method is based on the capture of the radical species in question (together with other products) in a solid inert gas matrix at very low temperatures, followed by recording matrix IR spectra of the respective product mixtures. The results presented in this paper proceed chiefly from the author's groups, and are supposed to give an impression of the possibilities and frontiers of the detection and IR spectroscopic characterization of radical species generated by way of very low pressure pyrolysis.