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[(Benzyloxy)methyl]dialkylsilyl-substitued 1,3-dithianes show in CI-MS an abundant loss of benzaldehyde from the [M + H](+) quasi-molecular ion. The fragmentation is explained with an intramolecular redox process, where a hydride is proposed to be transferred from the benzyl position to a neighboring thionium ion. This would form a particle that could readily lose benzaldehyde as a neutral fragment. The CI-MS results provide an explanation for the unusual instability of (benzyloxy)methyl-substituted silanes towards acids. In fact, the formation of benzaldehyde was established in the decomposition of a (benzyloxy)methyl-substituted acylsilane in the presence of Lewis or Bronsted acids and ethanethiol. The CI-MS study, therefore, represents a useful method to recognize unusual reactions that are - or might be - important in solution.

Neighboring‐Group Participation in the Gas Phase: Intramolecular Deacetalization of Hydroxyacetals under the Conditions of Chemical IonizationHerrn Prof. Dr. Christoph Tamm zum 70. Geburtstag gewidmet Under the conditions of chemical ionization (NH3, isobutane, ND3), hydroxyacetals do not show the expected [M + H+] signal, but the peak corresponding to the loss of the alcohol component of the acetal. This reaction is dependent on the presence of the OH group in the vicinity of the acetal and on the ring size of the heterocycle being formed. M+· is detected to a small extent as a consequence of charge exchange during chemical ionization.

The unusual chemical ionization mass spectrometric behavior of bis(benzyloxy)silanes showing heavy fragmentation and an [M - 1]+ fragment, instead of the expected [M + 1]+ ion with isobutane as the reactant gas, was investigated by means of (chloromethyl)bis(benzyloxy)methylsilane and model compounds. It could be shown that probably an intramolecular hydride transfer to an adjacent proton via a six-membered transition state gives rise to the uncommon [M - 1]+ quasi-molecular ion. Similar intramolecular reactions transferring a hydride, a chloromethyl, a phenyl or a benzyl group via cyclic transition states to a neighboring electrophile are held responsible for five of the six additional major fragments. The results demonstrate that fragmentation reactions become important in chemical ionization mass spectrometry if a molecule or an initially formed cluster ion possesses reactive groups which are in close proximity to each other.

Field-desorption and electron-impact mass spectral investigations of mono- and oligo-nuclear ferracyclic ring systems of type Fex(CO)y(C2R2)2 (x = 1, 2, 3: y = 6, 8) are described which for the first time show intense molecular ion peaks, which enable ready recognition of the molecular composition. The fragmentations and their dependence on the ion source and sample temperature, electron energy and sample-inlet mode under electron-impact conditions are discussed.

Mass spectral studies of the thermally labile ferracyclic complexes (1)–(4) and the related systems (5) and (6) result for the first time in the observation of intense molecular ion peaks by the use of special electron-impact and field-desorption techniques which enable a rapid determination of the basic composition of this type of compound.

Note on the Mass Spectral Decomposition of Monohalogenated Acetic Acids and its EstersBesides the well known ester fragmentation reactions two unusual decomposition reactions are observed in the mass spectra of the title compounds, leading to the ions [M‐CO2]+ and [M‐HX]+. The rearrangement reactions involved in the formation of these ions are discussed.

Chemischer InformationsdienstVolume 12, Issue 45 Physical Organic Chemistry ChemInform Abstract: MASS SPECTROMETRIC STUDIES. PART 36. MASS SPECTROMETRIC DECOMPOSITION OF MONOHALOGENATED ACETIC ACIDS AND ESTERS A. LORENZI-RIATSCH, A. LORENZI-RIATSCHSearch for more papers by this authorN. BILD, N. BILDSearch for more papers by this authorM. HESSE, M. HESSESearch for more papers by this author A. LORENZI-RIATSCH, A. LORENZI-RIATSCHSearch for more papers by this authorN. BILD, N. BILDSearch for more papers by this authorM. HESSE, M. HESSESearch for more papers by this author First published: November 10, 1981 https://doi.org/10.1002/chin.198145059AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume12, Issue45November 10, 1981 RelatedInformation

Chemischer InformationsdienstVolume 8, Issue 16 Physical Organic Chemistry ChemInform Abstract: MASS SPECTROMETRIC BEHAVIOR OF NITROGEN COMPOUNDS. 24. LOSS OF VINYL ALCOHOL FROM 1-AMINO-3-ARYLOXY-2-PROPANOLS UNDER ELECTRON IMPACT R. LONGONI, R. LONGONISearch for more papers by this authorP. BERNTSSON, P. BERNTSSONSearch for more papers by this authorN. BILD, N. BILDSearch for more papers by this authorM. HESSE, M. HESSESearch for more papers by this author R. LONGONI, R. LONGONISearch for more papers by this authorP. BERNTSSON, P. BERNTSSONSearch for more papers by this authorN. BILD, N. BILDSearch for more papers by this authorM. HESSE, M. HESSESearch for more papers by this author First published: April 19, 1977 https://doi.org/10.1002/chin.197716045AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume8, Issue16April 19, 1977 RelatedInformation

Loss of vinyl alcohol from 1‐amino‐3‐aryloxy‐2‐propanols under electron impactUnder electron impact compounds of type 1 (see Scheme 1) split off 44 mass units from the molecular ion. This unusual reaction was studied using derivatives and deuterium labelled compounds. It could be demonstrated that for this fragmentation reaction 16 is the important structural feature from which H2(C3)C(2)HOH (44 mass units) is lost. The preferred reaction mechanism involves a transition state in which four members of the side chain are involved (Scheme 2, mechanism 2).

The mass spectral behavior of substituted 2-phenyl-1, 3-dioxolanes has been studied. In the spectra of this group of compounds the most important peak is m/e 105 for which benzoylonium structure b is proposed. Another interestingion in the mass spectra of these compounds is c. This ion is protonated benzoic acid.

Chemischer InformationsdienstVolume 3, Issue 22 Heterocyclic Compounds ChemInform Abstract: MASSENSPEKTREN CYCLISCHER KETALE R. BOEHM, R. BOEHMSearch for more papers by this authorN. BILD, N. BILDSearch for more papers by this authorM. HESSE, M. HESSESearch for more papers by this author R. BOEHM, R. BOEHMSearch for more papers by this authorN. BILD, N. BILDSearch for more papers by this authorM. HESSE, M. HESSESearch for more papers by this author First published: May 30, 1972 https://doi.org/10.1002/chin.197222088Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. References R. BOEHM, N. BILD, M. HESSE, MASSENSPEKTREN CYCLISCHER KETALE, Helv. Chim. Acta, 1972, 55, 630. DOI: 10.1002/hlca.19720550236; 10.1002/hlca.19720550236 CASWeb of Science®Google Scholar Volume3, Issue22May 30, 1972 ReferencesRelatedInformation

AbstractVitamin B1, in chloride (1) or iodide form, decomposes thermally in the mass spectrometer mainly into 2‐methyl‐4‐amino‐5‐chloromethyl(iodomethyl)‐pyrimidine and 4‐methyl‐5‐β‐hydroxyethyl‐thiazole, and partly, by loss of HCl (HI) under cyclisation, into the base 2. The mass spectrum exhibits peaks due to these products and their fragments. The mass spectra of some model compounds are discussed.

AbstractBeim Vergleich der Massenspektren verschiedener N‐Oxide ergeben sich bezüglich der Pike M+‐16 und M+‐17 bei denjenigen aromatischer Amine allgemein gültige Verhaltensweisen. Die N‐Oxide aliphatischer Amine hingegen zeigen zusätzlich zu diesen beiden Zerfallsmöglichkeiten noch M+‐18‐Pike. Wenig intensive Molekular‐Ionenpike, thermische Abspaltung von O und H2O und das gänzliche Fehlen von M+‐16‐, M+‐17‐ und M+‐18‐Piken können neben den beiden Folgeprodukten der Cope‐Reaktion in hohem Masse den massenspektrometrischen Nachweis dieser Verbindungsklasse erschweren.