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This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.The Dissociation Energy of the CN Bond in Benzylamine
M. Szwarc
Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences
Vol. 198, No. 1053 (Aug. 15, 1949), pp. 285292
Published by: Royal Society
Stable URL: http://www.jstor.org/stable/98171
Page Count: 8
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Abstract
The kinetics of the thermal decomposition of benzylamine were studied by a flow method using toluene as a carrier gas. The decomposition produced NH3 and dibenzyl in a molar ratio of 1: 1, and small quantities of permanent gases consisting mainly of H2. Over a temperature range of 150 degrees (650 to 800 degrees C) the process was found to be a homogeneous gas reaction, following firstorder kinetics, the rate constant being expressed by k = 6 × 1012 exp (59,000/RT) sec.1. It was concluded, therefore, that the mechanism of the decomposition could be represented by the following equations: $ \matrix\format\l \\ \quad \text{C}_{6}\text{H}_{5}.\text{CH}_{2}.\text{NH}_{2}\rightarrow \text{C}_{6}\text{H}_{5}.\text{CH}_{\boldsymbol{2}}\boldsymbol{\cdot}+\text{NH}_{2}\boldsymbol{\cdot}, \\ \text{C}_{6}\text{H}_{5}.\text{CH}_{3}+\text{NH}_{2}\boldsymbol{\cdot}\rightarrow \text{C}_{6}\text{H}_{5}.\text{CH}_{2}\boldsymbol{\cdot}+\text{NH}_{3}, \\ \quad \quad \ 2\text{C}_{6}\text{H}_{5}.\text{CH}_{2}\boldsymbol{\cdot}\rightarrow \text{dibenzyl}, \endmatrix $ and the experimentally determined activation energy of 59 ± 4 kcal./mole is equal to the dissociation energy of the CN bond in benzylamine. Using the available thermochemical data we calculated on this basis the heat of formation of the NH2 radical as 35· 5 kcal./mole, in a fair agreement with the result obtained by the study of the pyrolysis of hydrazine. A review of the reactions of the NH2 radicals is given.
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Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences © 1949 Royal Society