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Formation and structure of [C 8 H 8 O] +˙ ions, generated from gas phase ions of phenyl‐cyclopropylcarbinol and 1‐phenyl‐1‐(hydroxymethyl)cyclopropane
Author(s) -
Dallinga J. W.,
Nibbering N. M. M.,
Louter G. J.
Publication year - 1981
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210160409
Subject(s) - cyclopropane , chemistry , hydroxymethyl , ion , enol , ring (chemistry) , phenylacetaldehyde , acetophenone , crystallography , stereochemistry , organic chemistry , catalysis
The structure and formation of [C 8 H 8 O] +. ions generated from phenylcyclopropylcarbinol and 1‐phenyl‐1‐hydroxymethylcyclopropane upon electron impact, have been studied using kinetic energy release measurements, by determination of ionization and appearance energies and by collisional activation. It is shown that the non‐decomposing [C 8 H 8 O] +˙ ions have exclusively the structure of the enol ion of phenylacetaldehyde, although it is less stable than the enol ion of acetophenone by about 45 kJ mol −1 . This has been interpreted as an indication that the [C 8 H 8 O] +˙ ions from phenylcyclopropylcarbinol are formed by an attack of either the phenyl ring or the hydroxyl group upon the C‐1C‐2 (or C‐1C‐3) bond of the cyclopropane ring under a simultaneous expulsion of ethene and migration of the attacking group to the C‐1 position. The [C 8 H 8 O] +˙ ion from 1‐phenyl‐1‐(hydroxymethyl)cyclopropane is formed by opening of the cyclopropane ring via a benzylic cleavage. A kinetically controlled hydrogen shift in the resulting ring opened ion prior to or during ethene loss then leads to the formation of [C 8 H 8 O] +˙ ions which have the structure of the enol ion of phenylacetaldehyde.