ISSN:
0030-493X
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The chemical ionization induced fragmentation behaviour of an open chain model compound, 5,7-undecanediol (meso and d,l stereoisomers), is studied and compared with that of previously studied alicyclic models, e.g. cyclohexanediols (cis and trans isomers). In close analogy to the latter, the major fragmentation processes are the one- and twofold loss of H2O from the protonated molecules [MH]+. As borne out by appropriately deuterium labelled analogues, the first loss of H2O is invariably a ‘clean’ heterolysis. The second loss is considerably more complex in that 1,3- and 1,4-elimination processes occur concurrently. While the 1,4-mode may be a direct elimination process in both types of compounds, the 1,3-mode is rearrangement induced in both. Whereas skeletal rearrangement (ring contraction) precedes this 1,3-elimination in the alicyclic models, hydrogen rearrangement (1,2-hydride shift) precedes it in the open chain model. No pronounced stereochemical effect is observed on the mechanistic course of the elimination processes, but is observed in their relative ease. The trimethylsilyl ethers of the stereoisomers of 5,7-undecanediol are also studied for analogous reactions, and are discussed in this context.
Additional Material:
5 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/oms.1210160111
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