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Methane Activation: Challenges and Improved Reactivity

Explore the challenges and improved reactivity in the activation of methane, including the selection of solvent and selective functionalization. Learn about the high yield, good selectivity, and steric control in ethane borylation.

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Methane Activation: Challenges and Improved Reactivity

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  1. Background • Activation of methane Strong C–H bonds Sparing solubility Poor chemoselectivity • Application R. A. Periana, D. J. Taube, Science 280, 560–564 (1998).

  2. Pioneering work Waltz, K. M.; He, X.; Muhoro, C.; Hartwig, J. F. J. Am. Chem. Soc. 1995, 117, 11357.

  3. Borylation of methane • Products • React pressure (8274 kPa) • Reaction with 3 • Chemoselectivity • Temperature (150℃)

  4. Mechanism

  5. Computational results

  6. Improved reactivity • Products • React pressure (1379-3447 kPa) • Reaction with 1 • Temperature (120℃) • Inverse relationship

  7. Overview • Application of computation • Rational experiment design

  8. Challenges • Strong C–H bonds of methane • Selection of solvent • Selective functionalization

  9. Background C. W. Liskey, J. F. Hartwig. J. Am. Chem. Soc. 134, 12422–12425 (2012). H. Chen, S. Schlecht, T. C. Semple, J. F. Hartwig, Science 287, 1995–1997 (2000). J. M. Murphy, J. F. Hartwig, J. Am. Chem. Soc. 128, 13684–13685 (2006).

  10. Background

  11. Rh catalyst

  12. Ir and Ru catalyst

  13. Comparison of time

  14. Comparison of selectivity Fig. 3. Evaluation of the selectivity in CH4/CH3Bpin borylation. (A to C) Reaction time profiles (top) for (A) Ir catalyst 2/3, (B) Rh catalyst 1, and (C) Ru catalyst 4. Red squares (left y axes) represent formation of CH2(Bpin)2, and blue circles (right y axes) represent formation of CH3Bpin. CH3Bpin: CH2(Bpin)2 ratios at early time points, relative rates, and DDG‡ values for the three catalyst systems are given below their respective time profile graphs.

  15. Comparison of catalysts for ethane borylation

  16. Overview • High yield • Good selectivity • Sterical control

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