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Abstract

In the Introduction, evidence is presented in support of the view that acetylene is a key intermediate in the production of carbon by the burning and pyrolysis of hydrocarbons. It is also pointed out that recent investigations of the decomposition of acetylene show that polyalkynes are the main products formed prior to carbon formation and that there is a need for kinetic information regarding the reactions of unsaturated radicals (mainly the ethynyl radical) with alkynes.

The Experimental Section describes the construction of a static vacuum apparatus. This comprises a quartz reactor which can be irradiated by a low-pressure mercury vapour lamp. Ethynyl radicals may be generated by the photolysis of monobromoethyne at 253.7 mm and the gaseous products formed in the reactor can be analysed by on-line gas chromatography.

The Results Section shows how the photolysis of monobromoethyne is affected by variations in photolysis time, initial pressure of monobromoethyne and pressures of added nitric oxide and inert gases. A description is also given of analytical measurements on the primary products formed by the reaction of ethynyl radicals with both alkanes and alkynes.

The Discussion Section shows that the ethynyl radical can react with an alkyne either by addition to a triple bond:

(MATHEMATICAL EQUATION CANNOT BE FORMATTED, READ THE ABSTRACT TO SEE)

The kinetic results indicate that all these reactions have low activation energies whilst hydrogen displacement reactions probably have activation energies and A factors of about 3 kcal.mol(superscript -1) and 10(superscript 8) 1.mole (superscript -1) sec (superscript -1) respectively, Using the data obtained from these experiments a new mechanism for acetylene pyrolysis is proposed and an outline is given of the probable role which the ethynyl radical plays in the reactions leading to carbon formation.

Publication Type:	Thesis (Doctoral)
Subjects:	Q Science > QD Chemistry
Departments:	School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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