UBC Theses and Dissertations

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UBC Theses and Dissertations

The thermal decomposition of cyclobutane at low pressures Ogawa, Rosalind


The thermal decomposition of cyclobutane is a homogeneous,unimolecular reaction;ethylene being the only product.The rate law :- K = 10¹⁵•³ e⁻⁶¹’⁰⁰⁰[symbol omitted] sec.⁻¹ was found to be obeyed in the pressure region 10 to 40 mm. and temperature range 398° to 450°C. Cyclobutane undergoes a wall reaction to form propylene and 1-butene. The high pressure rate constant falls off at low pressures and reaches a limiting low pressure rate when activation is maintained by collision with the walls of the reactor. The low pressure limiting rate decreases as the size of the reactor increases. The fall off curves gave best agreement with values of the Slater parameter, n, between 5 and 8, and values of the Kassel parameter, s, between 3 and 7. It was concluded that the ring vibrations are of major importance in the dissociation, and that the C—H bond vibrations are relatively unimportant. No evidence for a tetramethylene biradical intermediate was found. The reaction mechanism probably involves the simultaneous splitting of two opposite C—C bonds.

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