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Benzoic acid, 4-methyl-

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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

Data compiled as indicated in comments:
B - John E. Bartmess
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi

View reactions leading to C8H8O2+ (ion structure unspecified)

Quantity Value Units Method Reference Comment
Proton affinity (review)200.0kcal/molN/AHunter and Lias, 1998HL
Quantity Value Units Method Reference Comment
Gas basicity192.6kcal/molN/AHunter and Lias, 1998HL

Ionization energy determinations

IE (eV) Method Reference Comment
9.2 ± 0.2EIBenoit, 1973LLK
9.4PEMeeks, Wahlborg, et al., 1981Vertical value; LLK

Appearance energy determinations

Ion AE (eV) Other Products MethodReferenceComment
C7H7+12.6 ± 0.2COOHEIBenoit, 1973LLK
C8H7O+12.1 ± 0.2OHEIBenoit, 1973LLK

De-protonation reactions

C8H7O2- + Hydrogen cation = Benzoic acid, 4-methyl-

By formula: C8H7O2- + H+ = C8H8O2

Quantity Value Units Method Reference Comment
Deltar341.0 ± 2.1kcal/molG+TSKebarle and McMahon, 1977gas phase; B
Deltar340.7 ± 2.1kcal/molG+TSDecouzon, Exner, et al., 1996gas phase; relative to benzoate at 333.0 kcal/mol; B
Quantity Value Units Method Reference Comment
Deltar334.0 ± 2.0kcal/molIMREKebarle and McMahon, 1977gas phase; B
Deltar333.7 ± 2.0kcal/molIMREDecouzon, Exner, et al., 1996gas phase; relative to benzoate at 333.0 kcal/mol; 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]

Benoit, 1973
Benoit, F., Substituent effects in mass spectrometry. III. Substituent effects in the dissociation of the molecular ions of para and meta subtituted benzoic acids, Org. Mass Spectrom., 1973, 7, 295. [all data]

Meeks, Wahlborg, et al., 1981
Meeks, J.; Wahlborg, A.; McGlynn, S.P., Photoelectron spectroscopy of carbonyls: Benzoic acid and its derivatives, J. Electron Spectrosc. Relat. Phenom., 1981, 22, 43. [all data]

Kebarle and McMahon, 1977
Kebarle, P.; McMahon, T.B., Intrinsic Acidities of Substituted Phenols and Benzoic Acids Determined by Gas Phase Proton Transfer Equilibria, J. Am. Chem. Soc., 1977, 99, 7, 2222, https://doi.org/10.1021/ja00449a032 . [all data]

Decouzon, Exner, et al., 1996
Decouzon, M.; Exner, O.; Gal, J.-F.; Maria, P.-C., Non-classical Buttressing Effect: Gas-phase Ionization of Some Methyl Substituted Benzoic Acids, J. Chem. Soc. Perkin Trans., 1996, 2, 4, 475, https://doi.org/10.1039/p29960000475 . [all data]


Notes

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