A stereochemical approach toward a more detailed understanding of electron impact induced elimination reactions

Mark M. Green, Richard J. Cook, John M. Schwab, R. B. Roy

Research output: Contribution to journalArticle

Abstract

Electron impact induced elimination reactions involving the loss of small molecules, such as water and hydrogen chloride from alcohols and chlorides, possess considerable potential for the application of mass spectrometry to stereochemical problems. In the present work the elimination of water and hydrogen chloride has been found to obey identical steric driving forces in acyclic systems following the observation of equivalent propensity for the abstraction of the pro-R over the pro-S hydrogen at C-4 in (S)-2-pentyl alcohol and chloride. This similarity is not extended entirely in cyclohexanol and cyclohexyl chloride. Diastereotopic deuterium labeling has revealed that 1,4 elimination in both compounds is stereospecific while the 1,3 process is only stereospecific in the chloride. Ring opening has been proposed as a prerequisite to 1,3 elimination in cyclohexanol and this hypothesis allows correlation of the apparently dissimilar behavior of cyclic and acyclic alcohols and as well explains such anomalous results as a 90/1 difference for loss of water from the stereoisomers of 4-f-butylcyclohexanol while the derived chlorides exhibit stereoinsensitive loss of hydrogen chloride. Deuterium scrambling is found not to intervene in both low and high voltage measurement in these systems and thus offers a counterpoint to recent examples in ketones. A general theory is proposed connecting site selective hydrogen abstracting elimination reactions to the size of the heteroatom involved and findings on the model compounds studied here suggest that ground-state interatomic distances may be extrapolated to the ionized states in the mass spectrometer and thereby used to predict the positions of hydrogen abstraction.

Original languageEnglish (US)
Pages (from-to)3076-3083
Number of pages8
JournalJournal of the American Chemical Society
Volume92
Issue number10
StatePublished - 1970

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Chlorides
Electrons
Hydrochloric Acid
Hydrogen
Cyclohexanols
Deuterium
Alcohols
Water
Pentanols
Stereoisomerism
Voltage measurement
Mass spectrometers
Ketones
Labeling
Ground state
Mass spectrometry
Mass Spectrometry
Observation
Molecules

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

A stereochemical approach toward a more detailed understanding of electron impact induced elimination reactions. / Green, Mark M.; Cook, Richard J.; Schwab, John M.; Roy, R. B.

In: Journal of the American Chemical Society, Vol. 92, No. 10, 1970, p. 3076-3083.

Research output: Contribution to journalArticle

Green, Mark M. ; Cook, Richard J. ; Schwab, John M. ; Roy, R. B. / A stereochemical approach toward a more detailed understanding of electron impact induced elimination reactions. In: Journal of the American Chemical Society. 1970 ; Vol. 92, No. 10. pp. 3076-3083.
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