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A.F. Thomas

Bio: A.F. Thomas is an academic researcher. The author has contributed to research in topics: Fragmentation (mass spectrometry) & Mass spectrum. The author has an hindex of 1, co-authored 1 publications receiving 122 citations.

Papers
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Journal ArticleDOI
TL;DR: The mass spectra of a number of phenyl ethers in which the oxygen atom forms part of a heterocyclic ring have been measured and it is suggested that ions that are stabilized by the operation of the so-called "ortho-effect" are generally cyclic as mentioned in this paper.

122 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the Zerfallsreaktion organischer Molekule unter Elektronenbeschuss, die formal einer retro-Diels-Alder-Reaktion entspricht, wird diskutiert.

147 citations

Journal ArticleDOI
TL;DR: Several analytical cases of the main classes of components of the unsaponifiable matter obtained from olive oils or food matrices are reported, especially capillary gas chromatography.

105 citations

Journal ArticleDOI
TL;DR: Piperlongumine and piperlonguminine are shown to be N-(3,4,5-trimethoxycinnamoyl)-Δ5-piperidin-2-one and isobutylamide of piperic acid respectively.

101 citations

Book ChapterDOI
01 Jan 1978
TL;DR: In this paper, a review of electron impact induced ortho effects is presented, where the most important topics are hydrogen transfer and especially the question of concerted or multistep reaction, the influence of the structure on the selectivity of hydrogen migration via higher-membered transition states, the apparent cleavage of carbon/heteroatom bonds induced by hydrogen transfer, the redox processes which formally correspond to photochemical transformations, but which are completely different according to the reaction mechanisms, the different types of cyclization reactions, and the field of exchange processes preceding or accompanying unimolecular
Abstract: While in the early days of organic mass spectrometry the ortho effect was preferentially used as a diagnostic tool for structure elucidation, the recent research activities have concentrated on mechanisms and related aspects. Among these the following were the most important topics: hydrogen transfer and especially the question of concerted or multistep reaction; the influence of the structure on the selectivity of hydrogen migration via higher-membered transition states; the apparent cleavage of carbon/heteroatom bonds induced by hydrogen transfer; the redox processes which formally correspond to photochemical transformations, but which are completely different according to the reaction mechanisms; the different types of cyclization reactions; and the field of exchange processes preceding or accompanying unimolecular decompositions of ions in the gas phase. If a prognosis concerning the future activities in the field of electron impact induced ortho effects may be risked, the following aspects will probably become more important in addition to the topics discussed in this review: (i) Kinetic studies in the time range of nanoseconds to elucidate the time dependence of the different ortho effect reactions; (ii) ion/molecule reactions with the scope to obtain more information concerning the reactivities of open and closed shell systems; (iii) comparative studies in the fields of mass spectrometry, photochemistry and electrochemistry.

95 citations