The mass spectrometric fragmentation of n-alkanes |
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Authors: | Andr Lavanchy Raymond Houriet Tino Gumann |
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Institution: | André Lavanchy,Raymond Houriet,Tino Gäumann |
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Abstract: | The fragmentation of n-hexane, n-nonane and n-tetradecane under electron impact has been investigated, using 13C labelled compounds. The mechanism of the formation of the alkyl radical ions is quantitatively explained by using a method of calculation developed in an earlier publication for n-heptane. It is assumed that these ions are formed either by a direct C-C bond cleaveage or by a secondary olefin loss from an alkyl radical ion. In the latter case the probability for a particular carbon to be lost in the neutral fragment is assumed to be random. The probability for a direct cleavage to an alkyl ion is about 80% for an ion containing at least half of the number of carbon atoms of the molecular ion and 15% for the smaller ions. The M? H]+ ion seems to be a special case not yet clearly understood. Former results about the loss of methyl from the molecular ion are confirmed. |
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