Mass spectrometry, deuterium studies

The first mass spectrometric investigation of the thiazole ring was done by Clarke et al. (271). Shortly after, Cooks et al., in a study devoted to bicydic aromatic systems, demonstrated the influence of the benzo ring in benzothiazole (272). Since this time, many studies have been devoted to the influence of various types of substitution upon fragmentation schemes and rearrangements, in the case of alkylthiazoles by Buttery (273) arylthiazoles by Aune et al. (276), Rix et al. (277), Khnulnitskii et al. (278) functional derivatives by Salmona el al. (279) and Entenmann (280) and thiazoles isotopically labeled with deuterium and C by Bojesen et al. (113). More recently, Witzhum et al. have detected the presence of simple derivatives of thiazole in food aromas by mass spectrometry (281). 

His researches and those of his pupils led to his formulation in the twenties of the concept of active catalytic centers and the heterogeneity of catalytic and adsorptive surfaces. His catalytic studies were supplemented by researches carried out simultaneously on kinetics of homogeneous gas reactions and photochemistry. The thirties saw Hugh Taylor utilizing more and more of the techniques developed by physicists. Thermal conductivity for ortho-para hydrogen analysis resulted in his use of these species for surface characterization. The discovery of deuterium prompted him to set up production of this isotope by electrolysis on a large scale of several cubic centimeters. This gave him and others a supply of this valuable tracer for catalytic studies. For analysis he invoked not only thermal conductivity, but infrared spectroscopy and mass spectrometry. To ex-... 

As for silicon, secondary ion mass spectrometry (SIMS) is the most widely used profiling analysis technique for deuterium diffusion studies in III-V compounds. Deuterium advantageously replaces hydrogen for lowering the detection limit. The investigations of donor and acceptor neutralization effects have been usually performed through electrical measurements, low temperature photoluminescence, photothermal ionization spectroscopy (PTIS) and infrared absorption spectroscopy. These spectroscopic investigations will be treated in a separated part of this chapter. 

In another study, Streitwieser and Van Sickle (1962) measured the secondary /3-deuterium KIEs for the formation of carbanions from hydrocarbons with lithium cyclohexylamide in cyclohexylamine at 49.9°C. The rate constants needed for determining these KIEs for the formation of the carbanion (reaction (34)) were obtained by analysing the deuterium in the ethylbenzene recovered from the reaction at various times by mass spectrometry. 

Fragmentation of the nitroethylene radical cation has been studied by deuterium labelling and tandem mass spectrometry and compared to the fragmentation of the corresponding nitrosoethylene61. 

The gas-phase reactions of the fulvene radical cation with neutral 1,3-butadiene, alkenes and 2-propyl iodide have been investigated by Russell and Gross131a using ICR mass spectrometry. Unlike ionized benzene, ionized fulvene undergoes no C—C coupling with 2-propyl iodide. On the basis of deuterium and 13C labelling, the reaction of ionized fulvene with 1,3-butadiene was suggested to occur by [6 + 4] cycloaddition to yield tetrahydroazulene radical cations. Cycloadditions of neutral fulvene were also studied in this work. 

Andersen M.D., Shaffer J., Jennings P.A., Adams J.A. Structural characterization of protein kinase A as a function of nucleotide binding. Hydrogen-deuterium exchange studies using matrix-assisted laser desorption ionization-time of flight mass spectrometry detection. J. Biol. Chem. 2001, 276, 14204-14211. 

Englander J., Del Mar C., Li W, Englander S., Kim J., Stranz D., Hamuro Y., Woods Jr. V. Protein structure change studied by hydrogen-deuterium exchange, functional labeling, and mass spectrometry. Proc. Natl Acad. Sci. USA 2003, 100, 7057-7062. 

Ohashi, N., Furuuchi, S., and Yoshikawa, M. (1998). Usefulness of the hydrogen-deuterium exchange method in the study of drug metabolism using liquid chromatography-tandem mass spectrometry. J. Pharm. Biomed Anal. 18 325-334. 

Pan J, Rintala-Dempsey AC, Li Y, Shaw GS, Konermann L. 2006. Folding kinetics of the S100A11 protein dimer studied by time-resolved electrospray mass spectrometry and pulsed hydrogen-deuterium exchange. Biochemistry 45(9) 3005-3013. 

It has been shown by mass spectrometry that the deuteration of C60 leads to products richer in deuterium content in comparison to the hydrogenation which instead leads almost exclusively to C60H36 (Taylor 1999 Darwish et al. 1995). However, the spectra in Fig. 7.3 show that C60H36 and its deuterated analogous display the same band pattern apart the discussed isotopic shift and hence it is reasonable to state that C60D36 has been obtained and studied. This observation has been made also by other authors who have used also Raman in addition to FT-IR spectroscopy (Meletov et al 2001). 

Hydrogen-deuterium exchange experiments have been used extensively to study both structural parameters and dynamic and mechanistic aspects. They are utilized in conjunction with both NMR and IR studies. Mass spectrometry, with its high sensitivity and resolution, is ideally suited for isotopic exchange studies. 

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