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Issue 4, 1997
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Competitive charge-remote and anion-induced fragmentations of the non-8-enoate anion. A charge-remote reaction which co-occurs with hydrogen scrambling

Abstract

The non-8-enoate anion undergoes losses of the elements of C3H6, C4H8 and C6H12 on collisional activation. The mechanisms of these processes have been elucidated by a combination of product ion and labelling (2H and 13C) studies, together with a neutralisation reionisation mass spectrometric study. These studies allow the following conclusions to be made. (i) The loss of C3H6 involves cyclisation of the enolate anion of non-8-enoic acid to yield the cyclopentyl carboxylate anion and propene. (ii) The loss of ‘C4H8’ is a charge-remote process (one which proceeds remote from the charged centre) which yields the pent-4-enoate anion, butadiene and dihydrogen. This process co-occurs and competes with complex H scrambling. (iii) The major loss of ‘C6H12’ occurs primarily by a charge-remote process yielding the acrylate anion, hexa-1,5-diene and dihydrogen, but in this case no H scrambling accompanies the process. (iv) It is argued that the major reason why the two charge-remote processes occur in preference to anion-induced losses of but-1-ene and hex-1-ene from the respective 4- and 2-anions is that although these anions are formed, they have alternative and lower energy fragmentation pathways than those involving the losses of but-1-ene and hex-1-ene; viz. the transient 4-anion undergoes facile proton transfer to yield a more stable anion, whereas the 2-(enolate) anion undergoes preferential cyclisation followed by elimination of propene [see (i) above].

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Article information


J. Chem. Soc., Perkin Trans. 2, 1997, 695-702
Article type
Paper

Competitive charge-remote and anion-induced fragmentations of the non-8-enoate anion. A charge-remote reaction which co-occurs with hydrogen scrambling

S. Dua, J. H. Bowie, B. A. Cerda, C. Wesdemiotis, Mark. J. Raftery, J. F. Kelly, M. S. Taylor, S. J. Blanksby and M. A. Buntine, J. Chem. Soc., Perkin Trans. 2, 1997, 695
DOI: 10.1039/A607437E

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