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Benzene, 1,3-dimethyl-

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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 evaluated as indicated in comments:
HL - Edward P. Hunter and Sharon G. Lias
L - Sharon G. Lias

Data compiled as indicated in comments:
B - John E. Bartmess
MM - Michael M. Meot-Ner (Mautner)
LBLHLM - Sharon G. Lias, John E. Bartmess, Joel F. Liebman, John L. Holmes, Rhoda D. Levin, and W. Gary Mallard
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 C8H10+ (ion structure unspecified)

Quantity Value Units Method Reference Comment
IE (evaluated)8.55 ± 0.02eVN/AN/AL
Quantity Value Units Method Reference Comment
Proton affinity (review)194.1kcal/molN/AHunter and Lias, 1998HL
Quantity Value Units Method Reference Comment
Gas basicity187.9kcal/molN/AHunter and Lias, 1998HL

Proton affinity at 298K

Proton affinity (kcal/mol) Reference Comment
195.2Aue, Guidoni, et al., 2000Experimental literature data re-evaluated by the authors using ab initio protonation entropies; MM
193.4 ± 0.29Fernandez, Jennings, et al., 1989T = 370 - 750K; Reference Sprot(CH3)2O = 16.5 J/mol K in Hunter and Lias, 1998 needs to be re-evaluated; MM

Gas basicity at 298K

Gas basicity (review) (kcal/mol) Reference Comment
188.3Aue, Guidoni, et al., 2000Experimental literature data re-evaluated by the authors using ab initio protonation entropies; MM
187.0 ± 0.43Fernandez, Jennings, et al., 1989T = 370 - 750K; Reference Sprot(CH3)2O = 16.5 J/mol K in Hunter and Lias, 1998 needs to be re-evaluated; MM

Protonation entropy at 298K

Protonation entropy (cal/mol*K) Reference Comment
4.59Fernandez, Jennings, et al., 1989T = 370 - 750K; Reference Sprot(CH3)2O = 16.5 J/mol K in Hunter and Lias, 1998 needs to be re-evaluated; MM

Ionization energy determinations

IE (eV) Method Reference Comment
8.56PEHowell, Goncalves, et al., 1984LBLHLM
8.57 ± 0.01EQLias and Ausloos, 1978LLK
8.90 ± 0.05EILoudon and Mazengo, 1974LLK
8.50 ± 0.02PEMaier and Turner, 1973LLK
8.55 ± 0.05PIAkopyan and Vilesov, 1966RDSH
8.56PIBralsford, Harris, et al., 1960RDSH
8.56 ± 0.01PIWatanabe, 1957RDSH
8.56PEHowell, Goncalves, et al., 1984Vertical value; LBLHLM
8.82PEKimura, Katsumata, et al., 1981Vertical value; LLK
8.55PEKoenig, Tuttle, et al., 1974Vertical value; LLK
8.71 ± 0.015PEKobayashi and Nagakura, 1972Vertical value; LLK
8.75 ± 0.03PEKlessinger, 1972Vertical value; LLK

Appearance energy determinations

Ion AE (eV) Other Products MethodReferenceComment
C7H7+11.8 ± 0.2CH3EILoudon and Mazengo, 1974LLK
C7H7+11.4 ± 0.1CH3EINounou, 1966RDSH
C7H7+11.3 ± 0.1CH3PIAkopyan and Vilesov, 1966RDSH
C8H9+12.3 ± 0.2HEILoudon and Mazengo, 1974LLK
C8H9+11.7 ± 0.1HPIAkopyan and Vilesov, 1966RDSH
C8H9+11.8 ± 0.1HEITait, Shannon, et al., 1962RDSH

De-protonation reactions

C8H9- + Hydrogen cation = Benzene, 1,3-dimethyl-

By formula: C8H9- + H+ = C8H10

Quantity Value Units Method Reference Comment
Deltar381.0 ± 2.6kcal/molG+TSCaldwell and Bartmessgas phase; value altered from reference due to change in acidity scale; B
Quantity Value Units Method Reference Comment
Deltar373.9 ± 2.5kcal/molIMRECaldwell and Bartmessgas phase; value altered from reference due to change in acidity scale; 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.

Hunter and Lias, 1998
Hunter, E.P.; Lias, S.G., Evaluated Gas Phase Basicities and Proton Affinities of Molecules: An Update, J. Phys. Chem. Ref. Data, 1998, 27, 3, 413-656, https://doi.org/10.1063/1.556018 . [all data]

Aue, Guidoni, et al., 2000
Aue, D.H.; Guidoni, M.; Betowski, L.D., Ab initio calculated gas-phase basicities of polynuclear aromatic hydrocarbons, Int. J. Mass Spectrom., 2000, 201, 283. [all data]

Fernandez, Jennings, et al., 1989
Fernandez, T.; Jennings, K.R.; Mason, R.S., Gas-phase proton transfer reactions in xylene-dimethyl ether mixtures, J. Chem. Soc. Faraday Trans. 2, 1989, 85, 1813. [all data]

Howell, Goncalves, et al., 1984
Howell, J.O.; Goncalves, J.M.; Amatore, C.; Klasinc, L.; Wightman, R.M.; Kochi, J.K., Electron transfer from aromatic hydrocarbons and their «pi»-complexes with metals. Comparison of the standard oxidation potentials and vertical ionization potentials, J. Am. Chem. Soc., 1984, 106, 3968. [all data]

Lias and Ausloos, 1978
Lias, S.G.; Ausloos, P.J., eIonization energies of organic compounds by equilibrium measurements, J. Am. Chem. Soc., 1978, 100, 6027. [all data]

Loudon and Mazengo, 1974
Loudon, A.G.; Mazengo, R.Z., Steric strain and electron-impact. The behaviour of some n, n'-dimethyl- 1,1-binaphthyls, some n, n'-dimethylbiphenyls and model compounds, Org. Mass Spectrom., 1974, 8, 179. [all data]

Maier and Turner, 1973
Maier, J.P.; Turner, D.W., Steric inhibition of resonance studied by molecular photoelectron spectroscopy. Part 2. Phenylethylenes, J. Chem. Soc. Faraday Trans. 2, 1973, 69, 196. [all data]

Akopyan and Vilesov, 1966
Akopyan, M.E.; Vilesov, F.I., A mass-spectrometric study of the photo-ionisation of benzene derivatives at wavelengths up to 885 A, Zh. Fiz. Khim., 1966, 40, 125, In original 63. [all data]

Bralsford, Harris, et al., 1960
Bralsford, R.; Harris, P.V.; Price, W.C., The effect of fluorine on the electronic spectra and ionization potentials of molecules, Proc. Roy. Soc. (London), 1960, A258, 459. [all data]

Watanabe, 1957
Watanabe, K., Ionization potentials of some molecules, J. Chem. Phys., 1957, 26, 542. [all data]

Kimura, Katsumata, et al., 1981
Kimura, K.; Katsumata, S.; Achiba, Y.; Yamazaki, T.; Iwata, S., Ionization energies, Ab initio assignments, and valence electronic structure for 200 molecules in Handbook of HeI Photoelectron Spectra of Fundamental Organic Compounds, Japan Scientific Soc. Press, Tokyo, 1981. [all data]

Koenig, Tuttle, et al., 1974
Koenig, T.; Tuttle, M.; Wielesek, R.A., The He(I) photoelectron spectra of xylenes and metacyclophanes. A reassignment of the lowest ionic state of [2.2] metacyclophane, Tetrahedron Lett., 1974, 2537. [all data]

Kobayashi and Nagakura, 1972
Kobayashi, T.; Nagakura, S., Photoelectron spectra of nitro-compounds, Chem. Lett., 1972, 903. [all data]

Klessinger, 1972
Klessinger, M., Ionization potentials of substituted benzenes, Angew. Chem. Int. Ed. Engl., 1972, 11, 525. [all data]

Nounou, 1966
Nounou, P., Etude des composes aromatiques par spectrometrie de masse. I. Mesure des potentials d'ionisation et d'apparition par la methode du potential retardateur et interpretation des courbes d'ionisation differentielle, J. Chim. Phys., 1966, 63, 994. [all data]

Tait, Shannon, et al., 1962
Tait, J.M.S.; Shannon, T.W.; Harrison, A.G., The structure of substituted C7 ions from benzyl derivatives at the appearance potential threshold, J. Am. Chem. Soc., 1962, 84, 4. [all data]

Caldwell and Bartmess
Caldwell, G.; Bartmess, J.E., , Unpublished results. [all data]


Notes

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