Mass spectra of some partially fluorinated aliphatic compounds

The mass spectra of several fluorohydrocarbons are shown and discussed. The fragmentation of these compounds displays a close correlation with the molecular structure and points to the importance of the charge-stabilisation concept for the ion intensities. The iodo-derivatives show a large abundant molecular ion.     

Mass spectra and pyrolysis of some oxymethylene-linked perfluoroaromatic compounds

The mass spectra of four oxymethylene-linked perfluoroaromatic compounds are reported and discussed. Proposed ion structures are substantiated by precise mass measurement. The principal fragmentation pathways involving scission of oxygen to methylene bonds are supported by appropriate metastable peaks. Parallels between the electron-impact and thermal behaviour of two of these compounds are noted.     

Mass spectra of some quinoline hydroxamic acids and related compounds

The mass spectra of some 3- and 4-substituted quinoline hydroxamic acids and related compounds have been interpreted, and proposed fragmentations substantiated by means of deuterium-labeling and accurate mass determinations. All compounds examined gave abundant molecular ions; most showed strong [M ? 16]⁺ ions and weak [M ? 17]⁺ ions. The expulsion of CO and HCN molecules and H and HCO radicals were common subsequent decompositions. The spectrum of 4-hydroxy-2-methylquinazoline-3-oxide (VII) was unique and showed that nitric oxide was expelled from the molecular ion.     

Mass spectra of boron compounds

The infrared and Raman spectra of six compounds (trimethylsiloxyethylene, (CH₃)₃SiOCHCH₂, methoxytrimethylsilane, (CH₃)₃SiOCH₃, and their deuterated derivatives: (CD₃)₃SiOCHCH₂, (CH₃)₃SiOCDCD₂, (CD₃)₃SiOCH₃, (CH₃)₃SiOCD₃ have been analysed.The majority of the bands observed have been assigned, in particular those due to ν(SiO).The study of the vinyl compounds shows that the enoxysilane exists in two conformers, the major being the gauche and the minor the s-cis one.     

Mass spectra of some azoles

The principal electron-impact fragmentation patterns of 3,4,5-triphenyl-1,2,4-triazole, 2,5-diphenyl-1,3,4-thiadiazole, their perfluorinated analogues and 2,5-di(pentafluorophenyl)-1,3,4-oxadiazole have been established from metastable ion evidence and precise mass measurements. Although ions produced by expulsion of nitrogen from the molecular-ions of these compounds are of low abundance, the simultaneous expulsion of nitrogen and a C₇X₅ radical (X = H or F) gives rise to abundant ions.     

Mass spectra of some furanosesquiterpenes

Some of the fragmentation modes operating in a few furanosesquiterpenes have been established from accurate mass measurements and metastable data.     

Mass spectra of some silylaryladamantanes

Conclusions The molecular weight and the number and nature of the substituents, and also their position, can be determined from the mass spectra of silylaryladamantanes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 707–708, March, 1982.     

Mass spectra of some diazadiamides

Electron impact mass spectra at nominally low electron energies are reported for a series of diazadiamides. Diazadiamides are of interest because of their use as ligands in transition metal complexes.     

Mass spectra of some thionocarbamates

The mass spectra of a number O-alkylthionocarbamates with two, one or no alkyl substituents on the nitrogen atom are presented and discussed. The main primary fragmentation pathways are McLafferty rearrangements, including the double so-called protonated McLafferty rearrangement. Generally, rearrangement products give charge delocalized ions, which release hydroxyl or sulphydryl radicals and water or hydrogen sulphide, to produce stable fragments. It has been found that the position of alkyl moieties may be deduced on the basis of mass spectral fragmentation patterns.     

Mass spectra of some steroidal diols

The mass spectral fragmentations of a number of steroidal 3,5- and 4,5-diols and some derivatives have been examined using high resolution mass spectrometry and deuterium labelling. Although the 3,5- and 4,5-diols have very similar mass spectra those of the derived ketols are quite characteristic. A pathway for the formation of the important m/e 332 ion in the mass spectrum of cholestan-4β,5α-diol has been postulated.     

Mass spectra of some oxadiazole derivatives

The mass spectra of some substituted oxadiazoles have been determined and analysed with the aid of high resolution mass spectrometry. Some characteristic and major differences between their spectra have been noted, and possible rationalizations have been advanced. The main fragmentation patterns of the 1,3,4-oxadiazole derivatives have been interpreted in terms of diazirine intermediates. Specific skeletal rearrangement processes have been observed in the spectra of the 1,3,4- and 1,2,4-oxadiazoles, and possible mechanisms are proposed.     

Mass spectra of some 1,2,4-thiadiazoles

Substituted 1,2,4-thiadiazoles were found to undergo fragmentation by loss of RCN from the molecular ion with both 3- and 5-substituents being involved to some extent. This was followed by loss of sulfur to yield a nitrilium ion. With 5-hydrazino substituents, hydrogen transfer was observed from the substituent to a ring nitrogen atom.     

Mass spectra of some substituted imidazoles

Comparison of fragmentation pathways and high resolution measurements has revealed that the molecular ions of 1-(2-hydroxy-2-phenylethyl)imidazoles undergo elimination of benzaldehyde. The parent ions of trans-1-styrylimidazoles also cyclise in a manner similar to their photochemical reactivity. A rearrangement involving OH or OMe transfer between the trans-1-styryl and 5-acid or 5-methyl ester group of an imidazole is also described.     

Mass spectra of some sulphonyl azides

A series of sulphonyl azides decomposed upon electron-impact with loss of azide radical. This fragmentation was in marked contrast to the photochemical behaviour of the compounds. An interesting ortho-extrusion process occurred in the mass spectrum of 2,4,6-triisopropylbenzenesulphonyl azide.