Methyl radical

• Formula: CH₃
• Molecular weight: 15.0345
• IUPAC Standard InChI: InChI=1S/CH3/h1H3 Copy

  
• IUPAC Standard InChIKey: WCYWZMWISLQXQU-UHFFFAOYSA-N Copy
• CAS Registry Number: 2229-07-4
• Chemical structure:
  This structure is also available as a 2d Mol file or as a computed 3d SD file
  The 3d structure may be viewed using Java or Javascript.
• Isotopologues:
  • Methyl-d3 radical
  • Methyl-d3 radical
• Permanent link for this species. Use this link for bookmarking this species for future reference.
• Information on this page:
  • Gas phase thermochemistry data
  • Gas phase ion energetics data
  • References
  • Notes
• Other data available:
  • Reaction thermochemistry data
  • Ion clustering data
  • Vibrational and/or electronic energy levels
• Data at other public NIST sites:
  • Electron-Impact Ionization Cross Sections (on physics web site)
  • Gas Phase Kinetics Database
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• NIST / TRC Web Thermo Tables, professional edition (thermophysical and thermochemical data)

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Gas phase thermochemistry data

Go To: Top, Gas phase ion energetics data, References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Gas Phase Heat Capacity (Shomate Equation)

C_p° = A + B*t + C*t² + D*t³ + E/t²
H° − H°_298.15= A*t + B*t²/2 + C*t³/3 + D*t⁴/4 − E/t + F − H
S° = A*ln(t) + B*t + C*t²/2 + D*t³/3 − E/(2*t²) + G
    C_p = heat capacity (cal/mol*K)
    H° = standard enthalpy (kcal/mol)
    S° = standard entropy (cal/mol*K)
    t = temperature (K) / 1000.

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Gas phase ion energetics data

Go To: Top, Gas phase thermochemistry data, References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data evaluated as indicated in comments:
L - Sharon G. Lias

Data compiled as indicated in comments:
B - John E. Bartmess
LL - Sharon G. Lias and Joel F. Liebman
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
RDSH - Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron

View reactions leading to CH₃⁺ (ion structure unspecified)

Electron affinity determinations

Ionization energy determinations

Appearance energy determinations

Cation De-protonation reactions

CH₂^- +  =

By formula: CH₂^- + H⁺ = CH₃⁺

References

Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Chase, 1998
Chase, M.W., Jr., NIST-JANAF Themochemical Tables, Fourth Edition, J. Phys. Chem. Ref. Data, Monograph 9, 1998, 1-1951. [all data]

Tsang, 1996
Tsang, W., Heats of Formation of Organic Free Radicals by Kinetic Methods in Energetics of Organic Free Radicals, Martinho Simoes, J.A.; Greenberg, A.; Liebman, J.F., eds., Blackie Academic and Professional, London, 1996, 22-58. [all data]

Ellison, Engelking, et al., 1978
Ellison, G.B.; Engelking, P.C.; Lineberger, W.C., An experimental determination of the geometry and electron affinity of CH₃, J. Am. Chem. Soc., 1978, 100, 2556. [all data]

Feldman, Rackwitz, et al., 1977
Feldman, D.; Rackwitz, R.; Kaiser, H.J.; Heincke, E., Photodetachment bei einigen neagtiven molekulionen: P₂-, As₂-, CH₂-, CH₃-, S₃-, Z. Naturforsch. A:, 1977, 32, 600. [all data]

Bohme, Lee-Ruff, et al., 1972
Bohme, D.K.; Lee-Ruff, E.; Young, L.B., Acidity order of selected bronsted acids in the gas phase at 300K, J. Am. Chem. Soc., 1972, 94, 5153. [all data]

Check, Faust, et al., 2001
Check, C.E.; Faust, T.O.; Bailey, J.M.; Wright, B.J.; Gilbert, T.M.; Sunderlin, L.S., Addition of Polarization and Diffuse Functions to the LANL2DZ Basis Set for P-Block Elements, J. Phys. Chem. A,, 2001, 105, 34, 8111, https://doi.org/10.1021/jp011945l . [all data]

Page, 1972
Page, F.M., Experimental determination of the electron affinities of inorganic radicals, Adv. Chem. Ser., 1972, 36, 68. [all data]

Page and Goode, 1969
Page, F.M.; Goode, G.C., Negative Ions and the Magnetron., Wiley, NY, 1969. [all data]

Gaines and Page, 1968
Gaines, A.F.; Page, F.M., The Stabilities of Negative Ions.I. The Methyl-, Diphenylmethyl, and Triphenylmethyl Negative Ions, Int. J. Mass Spectrom. Ion Phys., 1968, 1, 4-5, 315, https://doi.org/10.1016/0020-7381(68)85008-9 . [all data]

Berkowitz, Ellison, et al., 1994
Berkowitz, J.; Ellison, G.B.; Gutman, D., Three methods to measure RH bond energies, J. Phys. Chem., 1994, 98, 2744. [all data]

Nagano, Murthy, et al., 1993
Nagano, Y.; Murthy, S.; Beauchamp, J.L., Thermochemical properties and gas-phase ion chemistry of phenylsilane investigated by FT-ICR spectrometry. Identification of parent- and fragment-ion structural isomers by their specific reactivities, J. Am. Chem. Soc., 1993, 115, 10805. [all data]

Houle and Beauchamp, 1979
Houle, F.A.; Beauchamp, J.L., Photoelectron spectroscopy of methyl, ethyl, isopropyl, and tert-butyl radicals. Implications for the thermochemistry and structures of the radicals and their corresponding carbonium ions, J. Am. Chem. Soc., 1979, 101, 4067. [all data]

Reeher, Flesch, et al., 1976
Reeher, J.R.; Flesch, G.D.; Svec, H.J., The mass spectra and ionization potentials of the neutral fragments produced during the electron bombardment of aromatic compounds, Org. Mass Spectrom., 1976, 11, 154. [all data]

Kaposi, Riedel, et al., 1975
Kaposi, O.; Riedel, M.; Sanchez, G.R., Mass-spectrometric study of electron-impact and heterogeneous pyrolytic decomposition of methyl bromide, Acta Chim. Acad. Sci. Hung., 1975, 85, 361. [all data]

Golob, Jonathan, et al., 1973
Golob, L.; Jonathan, N.; Morris, A.; Okuda, M.; Ross, K.J., The first ionization potential of the methyl radical as determined by photoelectron spectroscopy, J. Electron Spectrosc. Relat. Phenom., 1973, 1, 506. [all data]

Potts, Glenn, et al., 1972
Potts, A.W.; Glenn, K.G.; Price, W.C., General discussion, Faraday Discuss. Chem. Soc., 1972, 54, 64. [all data]

Jonathan, 1972
Jonathan, N., General discussion, Faraday Discuss. Chem. Soc., 1972, 54, 64. [all data]

Lossing and Semeluk, 1970
Lossing, F.P.; Semeluk, G.P., Free radicals by mass spectrometry. XLII.Ionization potentials and ionic heats of formation for C₁-C₄ alkyl radicals, Can. J. Chem., 1970, 48, 955. [all data]

Williams and Hamill, 1968
Williams, J.M.; Hamill, W.H., Ionization potentials of molecules and free radicals and appearance potentials by electron impact in the mass spectrometer, J. Chem. Phys., 1968, 49, 4467. [all data]

Chupka and Lifshitz, 1968
Chupka, W.A.; Lifshitz, C., Photoionization of CH₃⁺; heat of formation of CH₂, J. Chem. Phys., 1968, 48, 1109. [all data]

Elder, Giese, et al., 1962
Elder, F.A.; Giese, C.; Steiner, B.; Inghram, M., Photo-ionization of alkyl free radicals, J. Chem. Phys., 1962, 36, 3292. [all data]

Herzberg and Shoosmith, 1956
Herzberg, G.; Shoosmith, J., Absorption spectrum of free CH₃ and CD₃ radicals, Can. J. Phys., 1956, 34, 523. [all data]

Dyke, Jonathan, et al., 1976
Dyke, J.; Jonathan, N.; Lee, E.; Morris, A., Vacuum ultraviolet photoelectron spectroscopy of transient species, J. Chem. Soc. Faraday Trans. 2, 1976, 72, 1385. [all data]

Koenig, Balle, et al., 1975
Koenig, T.; Balle, T.; Snell, W., Helium(I) photoelectron spectra of organic radicals, J. Am. Chem. Soc., 1975, 97, 662. [all data]

Potts, Glenn, et al., 1972, 2
Potts, A.W.; Glenn, K.G.; Price, W.C., General discussion, Faraday Discuss. Chem. Soc., 1972, 54, 65. [all data]

Waldron, 1956
Waldron, J.D., The ionization and dissociation of methyl radicals on electron impact, Metropolitan Vickers Gaz., 1956, 27, 66. [all data]

Leopold, Murray, et al., 1985
Leopold, D.G.; Murray, K.K.; Miller, A.E.S.; Lineberger, W.C., Methylene: A study of the X3B1 and the 1A1 states by photoelectron spectroscopy of CH₂^- and CD₂^-, J. Chem. Phys., 1985, 83, 4849. [all data]

Notes

Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, References

• Symbols used in this document:
  

  AE	Appearance energy
  EA	Electron affinity
  IE (evaluated)	Recommended ionization energy
  S°gas,1 bar	Entropy of gas at standard conditions (1 bar)
  ΔfH(+) ion,0K	Enthalpy of formation of positive ion at 0K
  ΔfH°gas	Enthalpy of formation of gas at standard conditions
  ΔrG°	Free energy of reaction at standard conditions
  ΔrH°	Enthalpy of reaction at standard conditions

• Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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