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The pyrolysis of diallyl and reactions of allyl radicals with l-butene.

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Title: The pyrolysis of diallyl and reactions of allyl radicals with l-butene.
Author: Ruzicka, Dalibor Josef
Degree Master of Science - MSc
Program Chemistry
Copyright Date: 1958
Subject Keywords Allyl
Abstract: A study has been made of the pyrolysis of 1,5-hexadiene (diallyl) and of the reactions of the allyl radicals thus produced with 1-butene. The pyrolysis of 1,5-hexadiene was found to be first order and appears to proceed mainly by free radical reactions in the temperature range 460 - 520° C. However, molecular rearrangement in the formation of cyclohexene and benzene are possible. The over-all activation energy for the process was found to be 31.3 kcal/mole for an A factor of 10⁸˙⁵ min¯¹. The main products among the gaseous compounds were methane, ethane, ethylene, propylene, and 1-butene. The main liquid products were cyclopentene, cyclopentadiene, 1-hexene and benzene. Evidence was obtained for hydrogen abstraction by allyl and addition of the allyl radical to olefinic double bonds. Activation energies for the formation of methane, ethane, propane, ethylene, propylene and 1-butene were determined. Addition of approximately 5 % by volume of 1,5-hexadiene was found to increase the rate of the pyrolysis of 1-butene about 6-7 times at 506° C. The formation of C₅-cyclic products and methane was found to be proportional to (diallyl)½ . This provides kinetic evidence that allyl radicals are involved directly in the formation of these products in the sensitized decomposition and also that the primary step in the pyrolysis of diallyl involves the formation of two allyl radicals. Mechanism for the pyrolysis of diallyl and for the reactions of allyl with 1-butene are discussed. A brief study has also been made of the pyrolysis of 1-butene in the presence of acetaldehyde. The thermal decomposition of 1-butene sensitized by addition of 25% by volume of acetaldehyde was carried out at 477° C. The decomposition of acetaldehyde was found to be inhibited by the presence of 1-butene by a factor of more than two. 1-butene, which practically does not decompose at the above temperature by itself, decomposes appreciably in the presence of acetaldehyde.
URI: http://hdl.handle.net/2429/39961
Series/Report no. UBC Retrospective Theses Digitization Project [http://www.library.ubc.ca/archives/retro_theses/]
Scholarly Level: Graduate

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