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The α-Effect and Competing Mechanisms: The Gas-Phase Reactions of Microsolvated Anions with Methyl Formate

  • Research Article
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Journal of The American Society for Mass Spectrometry

Abstract

The enhanced reactivity of α-nucleophiles, which contain an electron lone pair adjacent to the reactive site, has been demonstrated in solution and in the gas phase and, recently, for the gas-phase SN2 reactions of the microsolvated HOO–(H2O) ion with methyl chloride. In the present work, we continue to explore the significance of microsolvation on the α-effect as we compare the gas-phase reactivity of the microsolvated α-nucleophile HOO–(H2O) with that of microsolvated normal alkoxy nucleophiles, RO–(H2O), in reactions with methyl formate, where three competing reactions are possible. The results reveal enhanced reactivity of HOO–(H2O) towards methyl formate, and clearly demonstrate the presence of an overall α-effect for the reactions of the microsolvated α-nucleophile. The association of the nucleophiles with a single water molecule significantly lowers the degree of proton abstraction and increases the SN2 and BAC2 reactivity compared with the unsolvated analogs. HOO–(H2O) reacts with methyl formate exclusively via the BAC2 channel. While microsolvation lowers the overall reaction efficiency, it enhances the BAC2 reaction efficiency for all anions compared with the unsolvated analogs. This may be explained by participation of the solvent water molecule in the BAC2 reaction in a way that continuously stabilizes the negative charge throughout the reaction.

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References

  1. Pliego, J.R., Riveros, J.M.: The gas-phase reaction between hydroxide ion and methyl formate: a theoretical analysis of the energy surface and product distribution. Chem Eur J 7, 169–175 (2001)

    Article  CAS  Google Scholar 

  2. Edwards, J.O., Pearson, R.G.: Factors determining nucleophilic reactivity. J Am Chem Soc 84, 16–24 (1962)

    Article  CAS  Google Scholar 

  3. Buncel, E., Wilson, H., Chuaqui, C.: Reactivity selectivity correlations. IV. The α-effect in SN2 reactions at sp3 carbon—the reactions of hydrogen-peroxide anion with methyl phenyl sulfates. J Am Chem Soc 104, 4896–4900 (1982)

    Article  CAS  Google Scholar 

  4. Dixon, J.E., Bruice, T.C.: α-Effect. V. Kinetic and thermodynamic nature of the α-effect for amine nucleophiles. J Am Chem Soc 94, 2052–2056 (1972)

    Article  CAS  Google Scholar 

  5. Fountain, K.R., Dunkin, T.W., Patel, K.D.: α-Effect with substituted N-methylbenzohydroxamates and substituted phenyldimethylsulfonium salts: toward understanding of an intrinsic α-effect. J Org Chem 62, 2738–2741 (1997)

    Article  CAS  Google Scholar 

  6. Fountain, K.R., Felkerson, C.J., Driskell, J.D., Lamp, B.D.: The α-effect in methyl transfers from S-methyldibenzothiophenium fluoroborate to substituted N-methylbenzohydroxamates. J Org Chem 68, 1810–1814 (2003)

    Article  CAS  Google Scholar 

  7. Gregory, M.J., Bruice, T.C.: α-Effect. II. Displacements on sp3-carbon. J Am Chem Soc 89, 4400–4402 (1967)

    Article  CAS  Google Scholar 

  8. McIsaac Jr., J.E., Subbaram, L.R., Subbaram, J., Mulhausen, H.A., Behrman, E.J.: Nucleophilic reactivity of peroxy anions. J Org Chem 37, 1037–1041 (1972)

    Article  CAS  Google Scholar 

  9. Fina, N.J., Edwards, J.O.: The α-effect. A review. Int J Chem Kinet 5, 1–23 (1973)

    Article  CAS  Google Scholar 

  10. Jencks, W.P., Carriuolo, J.: Reactivity of Nucleophilic reagents towards esters. J Am Chem Soc 82, 1778–1786 (1960)

    Article  CAS  Google Scholar 

  11. Bruice, T.C., Donzel, A., Huffman, R.W., Butler, A.R.: Aminolysis of phenyl acetates in aqueous solutions. VII. Observations on influence of salts, amine structure, and base strength. J Am Chem Soc 89, 2106–2121 (1967)

    Google Scholar 

  12. Nomura, Y., Kubozono, T., Hidaka, M., Horibe, M., Mizushima, N., Yamamoto, N., Takahashi, T., Komiyama, M.: Predominant role of basicity of leaving group in α-effect for nucleophilic ester cleavage. Bioorg Chem 32, 26–37 (2004)

    Article  CAS  Google Scholar 

  13. Dixon, J.E., Bruice, T.C.: α-Effect. IV. Additional observation on the α-effect employing malachite green as substrate. J Am Chem Soc 93, 6592–6597 (1971)

    Article  CAS  Google Scholar 

  14. Wiberg, K.B.: The mechanisms of hydrogen peroxide reactions. II. A comparison of the reactivity of hydroxyl ion and hydroperoxide ion toward benzonitrile. J Am Chem Soc 77, 2519–2521 (1955)

    Article  CAS  Google Scholar 

  15. Buncel, E., Um, I.H.: The α-effect and its modulation by solvent. Tetrahedron 60, 7801–7825 (2004)

    Article  CAS  Google Scholar 

  16. Isolani, P.C., Riveros, J.M.: Energy-requirements for indirect formation of cluster ions in gas-phase ion–molecule reaction of negative ions with esters of formic-acid. Chem Phys Lett 33, 362–364 (1975)

    Article  CAS  Google Scholar 

  17. DePuy, C.H., Della, E.W., Filley, J., Grabowski, J.J., Bierbaum, V.M.: Absence of an α-effect in the gas phase nucleophilic reactions of HOO–. J Am Chem Soc 105, 2481–2482 (1983)

    Article  CAS  Google Scholar 

  18. DePuy, C.H., Grabowski, J.J., Bierbaum, V.M., Ingemann, S., Nibbering, N.M.M.: Gas-phase reactions of anions with methyl formate and N,N-dimethylformamide. J Am Chem Soc 107, 1093–1098 (1985)

    Google Scholar 

  19. Frink, B.T., Hadad, C.M.: Flowing afterglow study of the gas phase nucleophilic reactions of some formyl, acetyl, and cyclic esters. J Chem Soc Perkin Trans 2, 2397–2407 (1999)

    Article  Google Scholar 

  20. Garver, J.M., Yang, Z., Wehres, N., Nichols, C.M., Worker, B.B., Bierbaum, V.M.: The α-effect in elimination reactions and competing mechanisms in the gas phase. Int J Mass Spectrom 330, 182–190 (2012)

    Article  Google Scholar 

  21. Johlman, C.L., Wilkins, C.L.: Gas-phase reactions of nucleophiles with methyl formate. J Am Chem Soc 107, 327–332 (1985)

    Article  CAS  Google Scholar 

  22. Takashima, K., Riveros, J.M.: Gas-phase pathways for ester hydrolysis. J Am Chem Soc 100, 6128–6132 (1978)

    Article  CAS  Google Scholar 

  23. Patterson, E.V., Fountain, K.R.: On gas-phase α-effects. I. The gas-phase manifestation and potential SET character. J Org Chem 71, 8121–8125 (2006)

    Article  CAS  Google Scholar 

  24. McAnoy, A.M., Paine, M.R.L., Blanksby, S.J.: Reactions of the hydroperoxide anion with dimethyl methylphosphonate in an ion trap mass spectrometer: evidence for a gas-phase α-effect. Org Biomol Chem 6, 2316–2326 (2008)

    Article  CAS  Google Scholar 

  25. McAnoy, A.M., Williams, J., Paine, M.R.L., Rogers, M.L., Blanksby, S.J.: Ion–molecule reactions of O, S-dimethyl methylphosphonothioate: evidence for intramolecular sulfur oxidation during VX perhydrolysis. J Org Chem 74, 9319–9327 (2009)

    Article  CAS  Google Scholar 

  26. Thomsen, D.L., Reece, J.N., Nichols, C.M., Hammerum, S., Bierbaum, V.M.: Investigating the α-effect in gas-phase SN2 reactions of microsolvated anions. J Am Chem Soc 135, 15508–15514 (2013)

    Article  CAS  Google Scholar 

  27. Thomsen, D.L., Reece, J.N., Nichols, C.M., Hammerum, S., Bierbaum, V.M.: The α-effect in gas-phase SN2 reactions of microsolvated anions: methanol as a solvent. J Phys Chem A (2013). doi:10.1021/jp407698a

  28. Van Doren, J.M., Barlow, S.E., DePuy, C.H., Bierbaum, V.M.: The tandem flowing afterglow-SIFT-drift. Int J Mass Spectrom Ion Process 81, 85–100 (1987)

    Article  Google Scholar 

  29. Bierbaum, V.M. In: Encyclopedia of Mass Spectrometry; Gross, M.L., Caprioli, R., Eds.; Vol. 1, Elsevier: Amsterdam, pp. 98–109 (2003)

  30. Bickelhaupt, F.M., de Koning, L.J., Nibbering, N.M.M.: Anionic ether cleavage of tetrahydrofuran in the gas-phase. Tetrahedron 49, 2077–2092 (1993)

    Article  CAS  Google Scholar 

  31. Su, T., Chesnavich, W.J.: Parametrization of the Ion-Polar Molecule Collision Rate Constant by Trajectory Calculations. J Chem Phys 76, 5183–5185 (1982)

    Article  CAS  Google Scholar 

  32. Frisch, M.J., Trucks, G.W., Schlegel, H.B., Scuseria, G.E., Robb, M.A., Cheeseman, J.R., Scalmani, G., Barone, V., Mennucci, B., Petersson, G.A., Nakatsuji, H., Caricato, M., Li, X., Hratchian, H.P., Izmaylov, A.F., Bloino, J., Zheng, G., Sonnenberg, J.L., Hada, M., Ehara, M., Toyota, K., Fukuda, R., Hasegawa, J., Ishida, M., Nakajima, T., Honda, Y., Kitao, O., Nakai, H., Vreven, T., Montgomery, J.A., Jr., Peralta, J.E., Ogliaro, F., Bearpark, M., Heyd, J.J., Brothers, E., Kudin, K.N., Staroverov, V.N., Kobayashi, R., Normand, J., Raghavachari, K., Rendell, A., Burant, J.C., Iyengar, S.S., Tomasi, J., Cossi, M., Rega, N., Millam, N.J., Klene, M., Knox, J.E., Cross, J.B., Bakken, V., Adamo, C., Jaramillo, J., Gomperts, R., Stratmann, R.E., Yazyev, O., Austin, A.J., Cammi, R., Pomelli, C., Ochterski, J.W., Martin, R.L., Morokuma, K., Zakrzewski, V.G., Voth, G.A., Salvador, P., Dannenberg, J.J., Dapprich, S., Daniels, A.D., Farkas, Ö., Foresman, J.B., Ortiz, J.V., Cioslowski, J., Fox, D.J. Gaussian 09, Revision B.01. Gaussian, Inc, Wallingford (2010)

  33. Ren, Y., Yamataka, H.: G2(+) Investigation on the α-effect in the SN2 reactions at saturated carbon. Chem Eur J 13, 677–682 (2007)

    Article  CAS  Google Scholar 

  34. Glukhovtsev, M.N., Pross, A., Radom, L.: Gas-phase identity SN2 reactions of halide anions with methyl halides—a high-level computational study. J Am Chem Soc 117, 2024–2032 (1995)

    Article  CAS  Google Scholar 

  35. Scott, A.P., Radom, L.: Harmonic vibrational frequencies: an evaluation of Hartree-Fock, Moller-Plesset, quadratic configuration interaction, density functional theory, and semiempirical scale factors. J Phys Chem 100, 16502–16513 (1996)

    Google Scholar 

  36. Bohme, D.K., Mackay, G.I.: Bridging the gap between the gas-phase and solution: transition in the kinetics of nucleophilic displacement-reactions. J Am Chem Soc 103, 978–979 (1981)

    Google Scholar 

  37. Bohme, D.K., Raksit, A.B.: Gas-phase measurements of the influence of stepwise solvation on the kinetics of nucleophilic displacement-reactions with CH3Cl and CH3Br at room-temperature. J Am Chem Soc 106, 3447–3452 (1984)

    Article  CAS  Google Scholar 

  38. Hierl, P.M., Ahrens, A.F., Henchman, M., Viggiano, A.A., Paulson, J.F., Clary, D.C.: Nucleophilic displacement as a function of hydration number and temperature: rate constants and product distribution for OD-(D2O)0,1,2 + CH3Cl at 200–500 K. J Am Chem Soc 108, 3142–3143 (1986)

    Google Scholar 

  39. Hierl, P.M., Paulson, J.F., Henchman, M.J.: Translational energy-dependence of cross-sections for reactions of OH–(H2O)n with CH3Cl and CH3Br. J Phys Chem 99, 15655–15661 (1995)

    Article  CAS  Google Scholar 

  40. Seeley, J.V., Morris, R.A., Viggiano, A.A.: Temperature dependences of the rate constants and branching ratios for the reactions of F–(H2O)(0–5) with CH3Br. J Phys Chem A 101, 4598–4601 (1997)

    Article  CAS  Google Scholar 

  41. Viggiano, A.A., Arnold, S.T., Morris, R.A., Ahrens, A.F., Hierl, P.M.: Temperature dependences of the rate constants and branching ratios for the reactions of OH–(H2O)(0–4) + CH3Br. J Phys Chem 100, 14397–14402 (1996)

    Article  CAS  Google Scholar 

  42. Pross, A., Shaik, S.S.: Reactivity–selectivity relationships. A quantum-mechanical approach to transition-state structure. application to the SN2 reaction of benzyl derivatives. J Am Chem Soc 103, 3702–3709 (1981)

    Article  CAS  Google Scholar 

  43. Bordwell, F.G., Clemens, A.H.: Correlation between the basicity of carbanions and their ability to transfer an electron. J Org Chem 46, 1035–1037 (1981)

    Google Scholar 

  44. Terrier, F., Mokhtari, M., Goumont, W., Halle, J.C., Buncel, E.: High Bronsted βnuc values in SNAr displacement. An indicator of the SET pathway? Org Biomol Chem 1, 1757–1763 (2003)

    Google Scholar 

  45. Hoz, S.: The α-effect: on the origin of transition-state stabilization. J Org Chem 47, 3545–3547 (1982)

    Article  CAS  Google Scholar 

  46. Paranjothy, M., Sun, R., Zhuang, Y., Hase, W.L.: Direct chemical dynamics simulations: coupling of classical and quasiclassical trajectories with electronic structure theory. Wiley Interdisc Rev Comput Mol Sci 3, 296–316 (2013)

    Article  CAS  Google Scholar 

  47. Otto, R., Xie, J., Brox, J., Trippel, S., Stei, M., Best, T., Siebert, M.R., Hase, W.L., Wester, R.: Reaction dynamics of temperature-variable anion water clusters studied with crossed beams and by direct dynamics. Faraday Discuss 157, 41–57 (2012)

    Article  CAS  Google Scholar 

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Acknowledgments

The authors gratefully acknowledge NSF (CHE-1012321 and CHE-1300886) for their support of the research. D.L.T thanks the Danish Chemical Society and the Augustinus Foundation, C.M.N. thanks the AFOSR, and J.N.R. thanks the Colorado Diversity Initiative for financial support.

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Authors and Affiliations

  1. Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100, Copenhagen, Denmark

    Ditte L. Thomsen & Steen Hammerum

  2. Department of Chemistry and Biochemistry, University of Colorado, 215 UCB, Boulder, CO, 80309, USA

    Ditte L. Thomsen, Charles M. Nichols, Jennifer N. Reece & Veronica M. Bierbaum

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  1. Ditte L. Thomsen
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  2. Charles M. Nichols
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Correspondence to Veronica M. Bierbaum.

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Thomsen, D.L., Nichols, C.M., Reece, J.N. et al. The α-Effect and Competing Mechanisms: The Gas-Phase Reactions of Microsolvated Anions with Methyl Formate. J. Am. Soc. Mass Spectrom. 25, 159–168 (2014). https://doi.org/10.1007/s13361-013-0781-z

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