Abstract
Several mass spectrometry methods were explored to determine the regiospecificity of deuterium substitutions in hydrocarbon mixtures. The case investigated in this work was that of ethane mixtures obtained by catalytic H-D exchange between either C2H6 and D2 or C2D6 and H2 over platinum surfaces. A total of ten isotopologs are possible, and were indeed detected in all cases. Deconvolution of low-resolution mass spectra was found sufficient to determine the composition of the gas mixtures in terms of the total number of deuterium substitutions, but not to identify symmetric versus asymmetric substitutions in the C2D2H4, C2D3H3, and C2D4H2 products. High-resolution mass spectrometry allowed the separation of the intensities due to C2X +4 fragments from those from molecular C2X +6 signals (X = H or D), and with that for a more accurate determination of the composition of the mixtures. Relative probabilities were determined for the symmetric versus asymmetric removal of X2 from C2X +6 ions and for isotope scrambling in the mass spectrometer, and with that information fairly good cracking patterns were then calculated for the C2X +4 fragments produced by each individual pure C2X6 isotopologue. However, total deconvolution of all ten components in the ethane mixtures obtained by H-D exchange catalysis was beyond the experimental accuracy of the measurements. Tandem mass spectrometry/collision-induced decomposition mass spectrometry (MS/CID-MS) proved more useful for this task. In particular, it was possible to determine the proportion of symmetric versus asymmetric double H-D exchange in samples for which the total ethane-d 2 (in the case of C2H6 + D2) or ethane-d 4 (with C2D6 + H2) amounted to only ∼3% on the ethane mix. A comparison with other analytical methods, NMR in particular, is provided.
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References
Thomas, A. F. Deuterium Labeling in Organic Chemistry; Appleton-Century-Crofts: New York, 1971.
Ozaki, A. Isotopic Studies of Heterogeneous Catalysis, Kodansha/Academic Press: Tokyo and New York, 1977.
Vederas, J. C. The Use of Stable Isotopes in Biosynthetic Studies. Nat. Prod. Rep. 1987, 4, 277–337.
De Meer, K. M.; Roef, M. J.; Kulik, W.; Jakobs, C. In Vivo Research with Stable Isotopes in Biochemistry, Nutrition, and Clinical Medicine. An Overview. Isotop. Environ. Health Studies 1999, 35, 19–37.
Heumann, K. G. Isotopic Analyses of Inorganic and Organic Substances by Mass Spectrometry. Int. J. Mass Spectrom. 1982, 45, 87–110.
Dienes, T.; Pastor, S. J.; Schurch, S.; Scott, J. R.; Yao, J.; Cui, S. L.; Wilkins, C. L. Fourier Transform Mass Spectrometry—Advancing Years (1992 Mid 1996). Mass Spectrom. Rev. 1996, 15, 163–211.
Loaiza, A.; Xu, M.; Zaera, F. On the Mechanism of the H-D Exchange Reaction in Ethane over Platinum Catalysts. J. Catal. 1996, 159, 127–139.
Aryafar, M.; Zaera, F. Kinetic Study of the Catalytic Oxidation of Alkanes over Nickel, Palladium, and Platinum Foils. Catal. Lett. 1997, 48, 173–183.
Ali, A. H.; Zaera, F. Kinetic Study on the Selective Catalytic Oxidation of 2-Propanol to Acetone over Nickel Foils. J. Mol. Catal. A 2002, 177, 215–235.
Amenomiya, Y.; Pottie, R. F. Mass Spectra of Some Deuteriated Ethanes. II. An Empirical Method of Calculation of the Spectra. Can. J. Chem. 1968, 46, 1741–1746.
Vidavsky, I.; Gross, M. L. In Handbook of Instrumental Techniques for Analytical Chemistry; Settle, F., Ed.; Prentice Hall: Upper Saddle River, NJ, 1997; pp 589–608.
Loaiza, A.; Borchardt, D.; Zaera, F. An NMR Method for the Analysis of Mixtures of Alkanes with Different Deuterium Substitutions. Spectrochim. Acta A 1997, 53, 2481–2493.
Zaera, F. An Organometallic Guide to the Chemistry of Hydrocarbon Moieties on Transition Metal Surfaces. Chem. Rev. 1995, 95, 2651–2693.
Zaera, F. Outstanding Mechanistic Questions in Heterogeneous Catalysis. J. Phys. Chem. B 2002, 106, 4043–4052.
Zaera, F. Surface Chemistry of Hydrocarbon Fragments on Transition Metals: Towards Understanding Catalytic Processes. Catal. Lett. 2003, 91, 1–9.
Zaera, F. On the Mechanism for the Hydrogenation of Olefins on Transition-Metal Surfaces: The Chemistry of Ethylene on Pt(111). Langmuir 1996, 12, 88–94.
Zaera, F. The Surface Chemistry of Hydrocarbons on Transition Metal Surfaces: A Critical Review. Isr. J. Chem. 1998, 38, 293–311.
Zaera, F. Probing Catalytic Reactions at Surfaces. Prog. Surf. Sci. 2001, 69, 1–98.
Zaera, F.; Tjandra, S. The Thermal Chemistry of Neopentyl Iodide on Ni(100) Surfaces: Selectivity between α-C-H and γ-C-H and between C-H and C-C Bond-Scission Steps in Chemisorbed Neopentyl Moieties. J. Am. Chem. Soc. 1996, 118, 12738–12746.
Zaera, F. Selectivity in Hydrocarbon Catalytic Reforming: A Surface Chemistry Perspective. Appl. Catal. A 2002, 229, 75–91.
Zaera, F. Preparation and Reactivity of Alkyl Groups Adsorbed on Metal Surfaces. Acc. Chem. Res. 1992, 25, 260–265.
Zaera, F.; Tjandra, S.; Janssens, T. V. W. Selectivity Among Dehydrogenation Steps for Alkyl Groups on Metal Surfaces: Comparison Between Nickel and Platinum. Langmuir 1998, 14, 1320–1327.
Davis, S. M.; Gillespie, W. D.; Somorjai, G. A. Deuterium Isotope Effects for Hydrocarbon Reactions Catalyzed Over Platinum Single Crystal Surfaces. J. Catal. 1983, 83, 131–140.
Brown, R.; Kemball, C.; Oliver, J. A.; Sadler, I. H. The Use of Deuterium NMR Spectroscopy in Mechanistic Studies of Alkane-Eexchange Reactions on Supported Platinum and Rhodium Catalysts. J. Chem. Res. 1985, 3201–3246 (M).
Lambert, J. B.; Shurvell, H. F.; Lightner, D. A.; Cooks, R. G. Organic Structural Spectroscopy; Prentice Hall: Upper Saddle River, NJ, 1998.
McLafferty, F. W. Tandem Mass Spectrometric Analysis of Complex Biological Mixtures. Int. J. Mass Spectrom. 2001, 212, 81–87.
Kienhuis, P. G. M.; Geerdink, R. B. A Mass Spectral Library Based on Chemical Ionization and Collision-Induced Dissociation. J. Chromatogr. A 2002, 974, 161–168.
Yinon, J. Advances in Forensic Applications of Mass Spectrometry, 2nd ed.; CRC Press: Boca Raton, FL, 2004.
Williams, J. D.; Burinsky, D. J. Mass Spectrometric Analysis of Complex Mixtures Then and Now: The Impact of Linking Liquid Chromatography and Mass Spectrometry. Int. J. Mass Spectrom. 2001, 212, 111–133.
Murata, M.; Izumikawa, M.; Tachibana, K.; Fujita, T.; Naoki, H. Labeling Pattern of Okadaic Acid from 18O2 and [18O2]Acetate Elucidated by Collision-Induced Dissociation Tandem Mass Spectrometry. J. Am. Chem. Soc. 1998, 120, 147–151.
Deng, Y. Z.; Pan, H.; Smith, D. L. Selective Isotope Labeling Demonstrates that Hydrogen Exchange at Individual Peptide Amide Linkages Can be Determined by Collision-Induced Dissociation Mass Spectrometry. J. Am. Chem. Soc. 1999, 121, 1966–1967.
Kim, M. Y.; Maier, C. S.; Reed, D. J.; Deinzer, M. L. Site-Specific Amide Hydrogen/Deuterium Exchange in E-coli Thioredoxins Measured by Electrospray Ionization Mass Spectrometry. J. Am. Chem. Soc. 2001, 123, 9860–9866.
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Published online August 6, 2004
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Loaiza, A., Zaera, F. Regiospecificity in deuterium labeling determined by mass spectrometry. J Am Soc Mass Spectrom 15, 1366–1373 (2004). https://doi.org/10.1016/j.jasms.2004.07.002
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DOI: https://doi.org/10.1016/j.jasms.2004.07.002