The mass spectra of some chromans

The mass spectra of 4-p-hydroxyphenyl-2,2,4-trimethylchroman and of its thia, selena and sulphonyl analogues are reported and discussed. Formal charge localization on the oxygen atom of the oxo compound is reflected in the production of an abundant [M - 15]⁺ ion. Lack of charge location on the heteroatom of the seleno compound leads to a retro-Diels-Alder reaction. The thio compound exhibits intermediate behaviour, but charge localization on the oxygen atoms is preferred in the sulphone.     

The mass spectra of some guanidines

The mass spectra of guanidine and ten of its derivatives have been studied under both high and low resolution conditions. Evidence was detected for the migration of methyl groups, the formation of intermediate three-membered ring structures and decompositions involving expulsion of N^. with release of kinetic energy.     

The mass spectra of some aromatic polyketones

The behaviour of some aromatic tri- and tetraoxo compounds and of their p-substituted derivatives under electron-impact has been investigated by means of high and low resolution mass spectrometry, metastable refocusing and deuterium labelling. Some characteristic fragmentation processes observed with these compounds indicate that their molecular ions exist in the enol form. The formation of principal fragment ions is discussed.     

The mass spectra of some cyclic ethers

The mass spectral fragmentations of the saturated five-, six- and seven-membered ring ethers have been determined by studying their site-specifically deuterated analogues by both high and low-resolution mass spectrometry. The initial processes, governing the fragmentations of the cyclic ethers are shown to be identical with the well-known processes of linear nonbranched ethers, i.e. predominant α-fisson in the lower members and predominant carbon-oxygen fisson with charge retention on the carbon atom in the higher members.     

The mass spectra of some 3,5-diarylisoxazoles

The mass spectra of several 3,5-diarylisoxazoles are reported. The fragmentation patterns of 3-aryl-5-phenyl- and 5-aryl-3-phenylisoxazoles are very significantly different.     

The mass spectra of some 1,3,2-oxazaphospholanes

The mass spectra of six 1,3,2-oxazaphospholanes have been obtained. The compounds studied give strong m/e=M lines; the relative stability of the molecular ion correlates with the structure of the molecule. During the process of dissociative ionization, cleavage of the C-C and the P-O bonds in the ring takes place, with the molecular ion losing a R'CHO molecule. It has been shown that the molecule of an olefin is formed from the molecular ion mainly through an alkoxy group. A probable process of dissociative ionization is the loss by the molecular ion of an alkoxy group or, in the case of the 2-chloro derivative, the loss of a Cl atom.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 894–897, July, 1973.     

The mass spectra of some pyrazole compounds

The mass spectra of ten pyrazole compounds have been determined. Fragmentation schemes have been derived by means of the metastable defocusing method. The predominant process is cleavage of the nitrogen-nitrogen bond resulting in expulsion of HCN. The process second in prominence is the loss of a nitrogen molecule after initial removal of a hydrogen radical or a substituent, giving the species [C₃H₂R]⁺, probably a cyclopropenyl ion. In general, the fragmentation pattern is strongly influenced by the substituent.     

The mass spectra of some 1,3,2-oxazaborolidines

Low resolution mass spectra of a series of alkylphenyl-1,3,2-oxazaborolidines are reported. The characteristic fragmentations are shown to be an aid to the elucidation of the substituents in the 1,3,2-oxazaborolidine ring by means of a ‘substituent shift’ technique.     

The mass spectra of some silver salts

Fifteen of twenty-four silver(I) carboxylates examined give useful electron impact mass spectra. The compounds vaporize at moderate temperatures, apparently mainly as dimer with traces of higher oligomer in only a few cases. The molecular ion for the dimer is generally weak or absent, with the most abundant silver containing ion being [Ag₂(O₂CR)]⁺ in most cases. Metastable defocusing and deuterium labeling experiments on silver acetate have established some of the fragmentation pathways. The reported loss of carbon dioxide from perfluorocarboxylates to give intense peaks for organosilver ions was not observed in this study. Attempts to obtain spectra on the silver salts of organic materials other than carboxylic acids were successful in several cases. Silver trifluoromethanesulfonate, although much less volatile, gives a spectrum and fragmentation very much like the carboxylates, whereas silver trifluoromethanethiolate gives a complex spectrum which suggests tetramer as a major gas phase species. Of three compounds examined which have silver to nitrogen bonding only silver(II) phthalocyanine is sufficiently volatile to give a spectrum without decomposition. The field desorption spectra of the four compounds examined all show the ions Ag_nX_{n ? 1} for X=acetate (n=1 ? 6), X=p-chlorobenzoate (n=1 ? 4), X=methanesulfonate (n=1 ? 7) and X=p-toluenesulfonate (n=1 ? 5).     

The mass spectra of some diterpene lactones

The molecular ions of some diterpenoid trans-γ-and δ-lactones have been shown to lose the elements of carbon dioxide. The corresponding cis-lactones do not undergo fission in this manner. A mechanism for this stereospecific fragmentation is proposed.     

The mass spectra of some corticosteroid boronates

The mass spectra of methyl, n-butyl, t-butyl, phenyl and cyclohexyl boronates of various classes of steroid are reported and discussed. Steroid types represented are 17α, 21-dihydroxy-20-ketones, 17α, 20, 21-triols, 17α, 20-diols, 20, 21-ketols. Each gives rise to characteristic fragmentation modes, although derivatives of the 20α- and 20β-hydroxy compounds have similar spectra.     

The mass spectra of some methyl alkanesulphinates

Mass Spectra of the methyl esters of ethane, n-propane, isopropane, n-butane, sec-butane and tert-butane sulphinic acids have been determined. In general, the parent ions are of low abundance and the most prevalent are the hydrocarbon ions which arise by α-cleavage. Other ions that serve to characterise these compounds are those from the CH₄SO₂ and HSO₂ fragments.     

The mass spectra of some pentafluorophenylthio derivatives

Ionic fragmentations induced by electron-impact on compounds of the type C₆F₅SX (X ? H, CH₃, COCH₃, Cl, C₆F₅) and (C₆F₅S)₂, (C₆F₅S)₂Hg, (C₆F₅S)₃As and (C₆F₅SCH₂)₂ have been studied. Principal features of the mass spectra are reported. The [C₆F₅S]⁺ ion (m/e 199) is predominant and its mode of fragmentation has been deduced. The precursor ions for m/e 199 have been examined in (C₆F₅)₂S, (C₆F₅S)₂, (C₆F₅S)₂Hg, (C₆F₅S)₃As and C₆F₅SCl. Ion kinetic energy spectra of (C₆F₅)₂S, (C₆F₅S)₂, (C₆F₅S)₂Hg and C₆F₅SCl have been recorded, and all contain peaks corresponding to the fragmentation of the [C₆F₅S]⁺ ion.     

The mass spectra of some vicinally substituted nitropyridines

The fragmentation behaviour of 22 vicinally substituted nitropyridines has been studied under electron impact conditions. The decomposition patterns were found to be strongly affected by interaction of the substituent with the nitro group and the ring nitrogen. AH fragmentation sequences depend to a great extent on the position of the substituent in the ring.     

The mass spectra of some fluorine-containing dimethyl esters

The mass spectra of esters of the general formula MeO₂C·[CF₂]_n·CO₂Me, n = 6 to 9, are reported and briefly discussed. Common features of the mass spectra are prominent peaks at [M ? CO₂], [M ? CO₂ ? C₂F₄] and [M ? CO₂ ? 2C₂F₄].     

The mass spectra of some triterpenoid dehydration products

The mass spectra of ten dehydration and solvolysis products obtained from β-amyrin and glycyrrhetic acid were studied. With the exception of those resulting from ‘backbone’ rearrangement, they exhibited conventional fragmentation due to the ring C chromophore, like the parent alcohols. Only those products with a contracted ring A suffered loss of an isopropyl radical. In the latter type, special fragmentation features were exhibited by the isopropylcyclopentene and by the isopropylidene products. These differences enabled the assignment of probable structures for two unknown derivatives.