Mass spectrometric investigation of benzyliderieaniline

The mass spectral fragmentation of benzylideneaniline has been studied by deuterium labelling. Under electron impact, molecular ions undergo simple fission at the phenyl–N, phenyl–C and C?N bonds, hydrogen migration reactions, and skeletal rearrangement fragmentations. Except in the skeletal rearrangement reactions, hydrogen scrambling does not feature in benzylideneaniline upon electron impact.     

Mass spectrometric investigation of carbohydrates

Conclusions The pathways of the fragmentation of completely methylated- methyl-L-arabopyranoside were studied in detail. The data obtained will serve as a basis for establishing the structure of the partially methylated pentopyranosides.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 277–283, February, 1967.The authors would like to express their deep gratitude to R. A. Khmel'nitskii and A. A. Polyakova for kindly permitting the use of a mass spectrometer, equipped with a multiloop oscillograph.     

Mass spectrometric investigation of carbohydrates

Conclusions The pathways of fragmentation of 2,3,4-tri-O-methyl--methyl-D-fucoside were studied. The data obtained serve as the basis for establishing the structure of partially methylated 6-deoxyhexoses.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 543–548, March, 1967.     

全乙酰化低聚木糖的质谱研究

本文报道了全乙酰化木糖(1)～木六糖(6)的电子轰击质谱(70eV,20eV)及化学电离(反应气体CH_4,i-C_4H_(10),NH_3)质谱的研究结果.根据亚稳峰及高分辨测定资料,阐述了木糖全乙酰化物的碎裂途径,讨论了木二糖～木六糖全乙酰化物的碎裂机理,指出了低聚木糖质谱的特征碎片离子.在所研究的电子轰击质谱中均未观察到分子离子,只有以NH_3为反应气体的化学电离质谱才获得准分子离子,其中全乙酰化木糖(1)～木三糖(3)的[M+NH_4]~+为基峰,而全乙酰化木四糖(4)～木六糖(6)的[M+NH_4]~+离子强度较弱。     

Mass spectrometric investigation of phenylthiovinyl chlorides

Three isomeric phenylthiovinyl chlorides (β-, E and Z, and α-) have been examined under EI and FI conditions with particular attention paid to the fragmentation leading to [C₈H₇S]⁺ ions via loss of Cl˙. Kinetic energy release data, MIKE and CAD MIKE spectra obtained with these precursors, as well as with model compounds, suggest the thioacylium ion PhCH₂CS⁺ as the predominant structure observed for the [C₈H₇S]⁺ species in all cases examined. A comparison is made with the solution behaviour of incipient β-thiovinyl carbenium ions, which are known to rearrange to the S-bridged thiirenium structure.     

Mass spectrometric investigation of bimolecular compounds

Two points involving molecular structure have been investigated using mass spectrometry. First, mass spectra have been obtained that indicate a rapid means for differentiating bimolecular compounds from other structural isomers. Second, the mass spectrometric method has been used to evaluate bonding within bimolecular compounds. Quinone compounds have been reacted with dhydroxybenzene compounds to produce quinhydrone products, and upon mass spectrometric analysis, the quinhydrones decompose to regenerate derivatives of the starting materials. Evaluation of the decomposition products suggests that the hydroxyl hydrogens are involved in a resonance structure, and while in symmetrical quinhydrones, the hydroxyl hydrogens are probably associated equally with each reactant, unsymmetrical quinhydrones generate an unbalanced electronic distribution that eliminates the complete equivalency of the hydrogens.     

Mass spectrometric studies of dithiophosphinato metal complexes

Electron impact induced fragmentation reactions of planar, tetrahedral, octahedral and oligomeric metal dithiophosphinates Me(II)L₂ (L=Et₂PS₂^?; Me(II)=Zn, Cd, Hg, Pb, Co, Mn, Ni, Pd, Pt), Me(III)L₃ (Me(III) = Sb, Bi, In, Rh, Ir) and (Me(I)I)_n (Me(I)/n=Tl/1, Au/2, Cu/4) have been studied. Fragmentation patterns, which are in accordance with metastable peak determinations by linked scans, are reported. In the case of the transition metals the spectra of the complexes show abundant [M]^+· predominantly metal containing ions and, the former being weak and the intensities of the latter being considerably reduced in the case of metal complexes with filled d shells. With planar or tetrahedral transition metal complexes no dependence of fragmentation on the coordination geometry can be observed. The dependence of fragmentation on d configuration, ionization energy of the metal and metal ligand π bonding is discussed. In the case of the oligomeric complexes strong metal-metal interaction is observed even under electron impact.     

Mass spectrometric investigation of transformed steroids and related compounds

Conclusions The basic pathways of the decomposition of certain polyhydroxyketones of the pregene series and their partially acetylated derivatives under electron impact were elucidated, and the principles relating the nature of the mass spectrum to the configuration of the substituents in the D ring were found.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2510–2515, November, 1973.     

Mass spectrometric investigation of acetylated amidosulfates of D-galactose

Conclusions Acetates of the 2-dimethylamidosulfate of galactose are characterized by the presence of peaks of ions with m/e 259, 245, 222, 199, 180, 139; for the 3-dimethylamidosulfate ions with m/e 288, 242, 200, 140 are observed; for the 4-dimethylamidosulfate m/e 288, 271, 245, 211; for the 6-dimethylamidosulfate m/e 455, 307, 234, 183.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1084–1088, May, 1975.     

Mass spectrometric investigation of substituted 1,3-emthiolane S-oxides

The electron impact mass spectrometry of four model 2-phenyl-2-alkyl-l,3-dithiolane S-oxides is described and discussed with the aid of B/E mass-analysed ion kinetic energy collisional spectroscopy and labelling experiments, as well as of fast atom bombardment spectra. The mechanisms of the common fragmentation patterns are given.     

Mass spectrometric decompositions of copper complexes with esters and amides of nicotinic acid

Mass spectrometric decompositions of complexes of nicotinic acid esters and amides with copper are discussed. Liquid secondary ion mass spectrometry (LSIMS) was used as an ionisation technique and metastable ion spectra were recorded by using B/E linked scans. The fragmentation pathways consist mainly of the loss of one ligand molecule and also the cleavage of amide or ester bonds. It may be possible, on the basis of cleaved neutral fragments, to determine the site of coordination in the gas phase. It was also found that the presence of a chlorine atom affects the fragmentation pathways of complexes.     

Mass spectrometric investigation of ethyl-containing siloxanes and aromatic silyl ethers

The mass spectra of four linear ethylsiloxanes and eight aromatic silyl ethers are reported. General fragmentation patterns for the benzyltriethylsilyl ethers and their vinylogues are discussed. The spectra of the ethylsiloxanes and ethers are compared with those of their methyl analogues.     

Mass spectrometric investigation of N-sulfonylated purine nucleic bases and nucleosides

The gas/phase behaviour of N-sulfonylated purine nucleic bases and nucleosides towards electron impact (EI) and matrix-assisted laser desorption/ionization (MALDI) occurring in a ion trap of a Fourier transform ion cyclotron resonance mass spectrometer is investigated. The influence of the storage time on the protonated molecule ([M+H](+)) abundance under EI conditions confirms that the formation of these ions proceeds through ion/molecule reactions. Using stored-waveform inverse Fourier transform (SWIFT) selective isolation of M(+.) or H(3)O(+), self-chemical ionization, M(+.)/M, and chemical ionization, H(3)O(+)/M, are detected. Investigation of specific EI expulsion of SO(2), SO(2)H and/or SO(2)H(2) from M(+.) and/or [M+H](+) shows that oxygen protonation in bond;SO(2)bond; proceeds faster than nitrogen protonation. Expulsion of SO(2) from molecular ions is not observed in MALDI mass spectra of nucleosides.     

Mass spectrometric investigation of buspirone drug in comparison with thermal analyses and MO-calculations

The buspirone drug is usually present as hydrochloride form of general formula C(21)H(31)N(5)O(2).HCl, and of molecular weight (MW)=421.96. It is an analgesic anxiolytic drug, which does not cause sedative or depression of central nervous system. In the present work it is investigated using electron impact mass spectral (EI-MS) fragmentation at 70 eV, in comparison with thermal analyses (TA) measurements (TG/DTG and DTA) and molecular orbital calculation (MOC). Semi-empirical MO calculation, PM3 procedure, has been carried out on buspirone both as neutral molecule (in TA) and the corresponding positively charged species (in MS). The calculated MOC parameters include bond length, bond order, particle charge distribution on different atoms and heats of formation. The fragmentation pathways of buspirone in EI-MS lead to the formation of important primary and secondary fragment ions. The mechanism of formation of some important daughter ions can be illuminated from comparing with that obtained using electrospray ESIMS/MS mode mass spectrometer through the accurate mass measurement determination. The losses of the intermediate aliphatic part (CH2)4 due to cleavage of N-C bond from both sides is the primary cleavage in both techniques (MS and TA). The PM3 provides a base for fine distinction among sites of initial bond cleavage and subsequent fragmentation of drug molecule in both TA and MS techniques; consequently the choice of the correct pathway of such fragmentation knowing this structural session of bonds can be used to decide the active sites of this drug responsible for its chemical, biological and medical reactivity.     

Mass spectrometric investigation of adduct formation by methylated cyclodextrins

FABMS has been employed to detect the formation of supramolecular adducts between methylated cyclodextrins and (i) organic ammonium salts, (ii) organometallic cations, and (iii) neutral metalloorganic complexes. This is a facile technique for studying the second sphere coordination of transition metal complexes by chemically-modified cyclodextrins.     

Mass spectrometric investigation of isomeric 1,2,3,4-tetrahydro-4-oxoquinazolines

Six isomeric methylphenyl-1,2,3,4-tetrahydro-4-oxoquinazolines have been prepared and their fragmentation patterns upon electron impact studied. Deuterium labelling and high-resolution measurements were performed in order to facilitate the interpretation of the spectra. The dissociation of the molecular ion follows two main routes, the fragmentation being governed by the position of the phenyl group.