MeO anion
- Formula: CH3O-
- Molecular weight: 31.0345
- CAS Registry Number: 3315-60-4
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Gas phase ion energetics data
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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Data compiled by: John E. Bartmess
Electron affinity of neutral species
| EAneutral (eV) | Method | Reference | Comment |
|---|---|---|---|
| 1.5690 ± 0.0019 | LPES | Nee, Osterwalder, et al., 2006 | |
| 1.5720 ± 0.0040 | LPES | Ramond, Davico, et al., 2000 | |
| 1.5680 ± 0.0050 | LPES | Osborn, Leahy, et al., 1998 | |
| 1.685 ± 0.094 | D-EA | Bartmess, Scott, et al., 1979 | 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 |
| 1.570 ± 0.022 | LPES | Engleking, Ellison, et al., 1978 | Confirmed by high level calculations: Hiraoka, Shimizu, et al., 1995 |
| 1.591 ± 0.040 | PD | Janousek, Zimmerman, et al., 1978 | |
| <1.591 ± 0.039 | PD | Reed and Brauman, 1975 | |
| 2.59998 | EIAE | Tsuda and Hamill, 1964 | From MeOMe |
| 0.3816 | SI | Page and Goode, 1969 | The Magnetron method, lacking mass analysis, is not considered reliable. |
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 |
| ΔrG° | 376.04 ± 0.55 | kcal/mol | H-TS | Osborn, Leahy, et al., 1998 | gas phase |
| 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 |
| ΔrG° | 374.6 ± 2.1 | kcal/mol | H-TS | Haas and Harrison, 1993 | gas phase; Both metastable and 50 eV collision energy. |
| 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 |
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.
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]
Ramond, Davico, et al., 2000
Ramond, T.M.; Davico, G.E.; Schwartz, R.L.; Lineberger, W.C.,
Vibronic structure of alkoxy radicals via photoelectron spectroscopy,
J. Chem. Phys., 2000, 112, 3, 1158-1169, https://doi.org/10.1063/1.480767
. [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]
Engleking, Ellison, et al., 1978
Engleking, P.C.; Ellison, G.B.; Lineberger, W.C.,
Laser photodetachment electron spectrometry of methoxide, deuteromethoxide, and thiomethoxide: Electron affinities and vibrational structure of CH3O, and CH3S,
J. Chem. Phys., 1978, 69, 1826. [all data]
Hiraoka, Shimizu, et al., 1995
Hiraoka, K.; Shimizu, A.; Minamitsu, A.; Nasu, M.; Fujimaki, S.; Yamabe, S.,
The small binding energies of the negative cluster ions: SF5-(SF6)1, SF6-(SF6)1 and F-(SF6)n (n=1 and 2), in the gas phase,
Chem. Phys. Lett., 1995, 241, 5-6, 623, https://doi.org/10.1016/0009-2614(95)00676-U
. [all data]
Janousek, Zimmerman, et al., 1978
Janousek, B.K.; Zimmerman, A.H.; Reed, K.J.; Brauman, J.I.,
Electron detachment from aliphatic molecular anions. Gas phase electron affinites of methoxyl, tert-butoxyl, and neopentoxyl radicals,
J. Am. Chem. Soc., 1978, 100, 6142. [all data]
Reed and Brauman, 1975
Reed, K.J.; Brauman, J.I.,
Electron affinities of alkoxy radicals and the bond dissociation energies in aliphatic alcohols,
J. Am. Chem. Soc., 1975, 97, 1625. [all data]
Tsuda and Hamill, 1964
Tsuda, S.; Hamill, W.H.,
Ionization Efficiency Measurements by the Retarding Potential Difference Method,
Adv. Mass Spectrom., 1964, 3, 249. [all data]
Page and Goode, 1969
Page, F.M.; Goode, G.C.,
Negative Ions and the Magnetron., Wiley, NY, 1969. [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:
EAneutral Electron affinity of neutral species 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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