Methoxy radical
- Formula: CH3O
- Molecular weight: 31.0339
- IUPAC Standard InChI: InChI=1S/CH3O/c1-2/h1H3
- IUPAC Standard InChIKey: GRVDJDISBSALJP-UHFFFAOYSA-N
- CAS Registry Number: 2143-68-2
- Chemical structure:
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Gas phase ion energetics data
Go To: Top, 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
LBLHLM - Sharon G. Lias, John E. Bartmess, Joel F. Liebman, John L. Holmes, Rhoda D. Levin, and W. Gary Mallard
View reactions leading to CH3O+ (ion structure unspecified)
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| IE (evaluated) | 10.72 | eV | N/A | N/A | L |
| Quantity | Value | Units | Method | Reference | Comment |
| ΔfH(+) ion,0K | 253.1 | kcal/mol | N/A | N/A |
Ionization energy determinations
| IE (eV) | Method | Reference | Comment |
|---|---|---|---|
| 10.72 | DER | Ruscic and Berkowitz, 1991 | LL |
| 8.6 | DER | Lias, Bartmess, et al., 1988 | LL |
| 8.3 ± 0.3 | CIEL | Griffiths and Harris, 1987 | LBLHLM |
| 7.37 ± 0.03 | PE | Dyke, 1987 | LBLHLM |
Appearance energy determinations
| Ion | AE (eV) | Other Products | Method | Reference | Comment |
|---|---|---|---|---|---|
| CHO+ | 8.73 | H2 | PI | Kuo, Zhang, et al., 1994 | LL |
Anion protonation reactions
CH3O- + =
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔrH° | 382. ± 2. | kcal/mol | AVG | N/A | Average of 6 values; Individual data points |
| Quantity | Value | Units | Method | Reference | Comment |
| ΔrG° | 376.02 ± 0.62 | kcal/mol | H-TS | Nee, Osterwalder, et al., 2006 | gas phase; B |
| ΔrG° | 376.04 ± 0.55 | kcal/mol | H-TS | Osborn, Leahy, et al., 1998 | gas phase; B |
| ΔrG° | 374.0 ± 2.0 | kcal/mol | IMRE | Bartmess, Scott, et al., 1979 | gas phase; The acidity is 1.2 kcal/mol stronger than that from the D-EA cycle, due to the multi-compound fit for the acidity scale.; value altered from reference due to change in acidity scale; B |
| ΔrG° | 374.6 ± 2.1 | kcal/mol | H-TS | Haas and Harrison, 1993 | gas phase; Both metastable and 50 eV collision energy.; B |
| ΔrG° | 375.10 ± 0.60 | kcal/mol | TDEq | Meot-ner and Sieck, 1986 | gas phase; Experimental entropy: 21.5 eu, 0.6 less than H2O; B |
References
Go To: Top, 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.
Ruscic and Berkowitz, 1991
Ruscic, B.; Berkowitz, J.,
Photoionization mass spectrometric studies of the isomeric transient species CD2OH and CD3O,
J. Chem. Phys., 1991, 95, 4033. [all data]
Lias, Bartmess, et al., 1988
Lias, S.G.; Bartmess, J.E.; Liebman, J.F.; Holmes, J.L.; Levin, R.D.; Mallard, W.G.,
Gas-phase ion and neutral thermochemistry,
J. Phys. Chem. Ref. Data, Suppl. 1, 1988, 17, 1-861. [all data]
Griffiths and Harris, 1987
Griffiths, W.J.; Harris, F.M.,
Ionization energies of CH3O and CH3S radicals measured by charge-inversion energy-loss spectrometry,
Chem. Phys. Lett., 1987, 142, 7. [all data]
Dyke, 1987
Dyke, J.M.,
Properties of gas-phase ions,
J. Chem. Soc. Faraday Trans., 1987, 83, 69. [all data]
Kuo, Zhang, et al., 1994
Kuo, S.-C.; Zhang, Z.; Klemm, R.B.; Liebman, J.F.; Stief, L.J.; Nesbitt, F.L.,
Photoionization of hydroxymethyl (CD2OH and CD3O) radicals: Photoion efficiency spectra, ionization energies and thermochemistry,
J. Phys. Chem., 1994, 98, 4026. [all data]
Nee, Osterwalder, et al., 2006
Nee, M.J.; Osterwalder, A.; Zhou, J.; Neumark, D.M.,
Slow electron velocity-map imaging photoelectron spectra of the methoxide anion,
J. Chem. Phys., 2006, 125, 1, 014306, https://doi.org/10.1063/1.2212411
. [all data]
Osborn, Leahy, et al., 1998
Osborn, D.L.; Leahy, D.J.; Kim, E.H.; deBeer, E.; Neumark, D.M.,
Photoelectron spectroscopy of CH3O- and CD3O-,
Chem. Phys. Lett., 1998, 292, 4-6, 651-655, https://doi.org/10.1016/S0009-2614(98)00717-9
. [all data]
Bartmess, Scott, et al., 1979
Bartmess, J.E.; Scott, J.A.; McIver, R.T., Jr.,
The gas phase acidity scale from methanol to phenol,
J. Am. Chem. Soc., 1979, 101, 6047. [all data]
Haas and Harrison, 1993
Haas, M.J.; Harrison, A.G.,
The Fragmentation of Proton-Bound Cluster Ions and the Gas-Phase Acidities of Alcohols,
Int. J. Mass Spectrom. Ion Proc., 1993, 124, 2, 115, https://doi.org/10.1016/0168-1176(93)80003-W
. [all data]
Meot-ner and Sieck, 1986
Meot-ner, M.; Sieck, L.W.,
Relative acidities of water and methanol, and the stabilities of the dimer adducts,
J. Phys. Chem., 1986, 90, 6687. [all data]
Notes
Go To: Top, Gas phase ion energetics data, References
- Symbols used in this document:
AE Appearance energy IE (evaluated) Recommended ionization energy ΔfH(+) ion,0K Enthalpy of formation of positive ion at 0K 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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