Date of Graduation

1972

Document Type

Dissertation

Degree Type

PhD

Department

Chemistry

Committee Chair

C. Gordon McCarty

Committee Co-Chair

Vincent J. Traynelds

Committee Member

D.W.H. MacDowell

Committee Member

Peter Popovich

Committee Member

Keith Gosling

Committee Member

Robert J. Borgman

Abstract

In all of the alcohol oxidations referred to previously, the alcohol was converted to some other substance (e.g., to tosylate, halide) before reaction with DMSO. Many alcohols, however, have been allowed to react with DMSO without prior conversion.⁴⁹ Traynelis et al. found that dehydration was the usual result when secondary and tertiary benzylic alcohols or tertiary aliphatic alcohols were heated at 160–185° in DMSO for nine to sixteen hours (equations 53 and 54). The dehydration of eleven alcohols was reported, and evidence suggested a carbonium ion mechanism.⁵⁰ A subsequent modification of reaction conditions permitted the dehydration of alcohols previously found to be resistant. A higher reaction temperature (190°) was necessary, as well as extended reaction times (48 hours). 1-Alkylcycloalkanols were also reported to dehydrate, but pinacols not only dehydrated but rearranged. This latter observation, as well as the formation of ether as well as olefin in some experiments, further reinforced the carbonium ion hypothesis, although no details of mechanism were advanced. Also in 1964, Traynelis and Hergenrother reported their results of a study of benzyl alcohol oxidations. Various ortho- and para-substituted benzyl alcohols were found to undergo conversion to the corresponding aldehyde if the DMSO solution was refluxed and if a stream of air was passed through it. Very little oxidation of the aldehyde to the corresponding acid occurred. Several things were interesting. Although oxygen is necessary for the reaction, it did not appear to be consumed as the oxidation progressed. If the reactions were carried out under a blanket of nitrogen, no oxidation took place. If t-butyl peroxide was introduced under oxygen-free conditions, then aldehyde formation was noted. The requirement for oxygen, and the success of the radical initiator, seemed to require a free radical mechanism for the reaction. On the other hand, electron-withdrawing substituents in the para position of benzyl alcohol seemed to slow the oxidation reaction, whereas electron-releasing ones greatly increased it. The latter results seemed to require a carbonium ion interpretation. It was to settle this question that a detailed study of the oxidation mechanism was undertaken. Reproduced with permission of the copyright owner. Further reproduction prohibited.

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