K. Guthier, P. Hebgen, K. Homann
Apr 1, 1995
Citations
0
Influential Citations
12
Citations
Journal
Liebigs Annalen
Abstract
The pyrolysis of ethynylbenzene (1) in helium was studied in a tubular flow reactor at 10.7 mbar/1030°C and reaction times ranging from 5 to 30 ms. Reactive intermediates such as radicals and carbenes were scavenged with dimethyl disulfide (DMDS), Qualitative and quantitative analysis of the scavenging products and of the stable pyrolysis products were carried out by GC-MS analysis. – The radicals phenyl (2a), o-, m-, and p-ethynylphenyl (1c, d, e), 2- and 1-phenyl-vinyl (1a, b) 1- and 2-naphthyl (3a, b), methyl, hydrogen atoms, and radicals resulting from the addition of phenyl and ethynylphenyl radicals to the triple bond of ethynylbenzene were detected. Carbenes, such as phenylvinylidene, occur only in small traces and obviously play no role in the overall pyrolysis. Concentration profiles of the radicals and of some important pyrolysis products are presented and discussed. Based on the detected radicals, a reaction scheme for the pyrolysis of ethynylbenzene is proposed. Results of pyrolyses of mixtures of ethynylbenzene and ethyne show that naphthalene (3), acenaphthylene (12), and other compounds are produced by a sequence of ethyne addition and cyclization reactions.