p-Xylene

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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)8.44 ± 0.05eVN/AN/AL
Quantity Value Units Method Reference Comment
Proton affinity (review)794.4kJ/molN/AHunter and Lias, 1998HL
Quantity Value Units Method Reference Comment
Gas basicity766.8kJ/molN/AHunter and Lias, 1998HL

Electron affinity determinations

EA (eV) Reference Comment
0.001519 ± 0.000087Hammer, Diri, et al., 2003B

Proton affinity at 298K

Proton affinity (kJ/mol) Reference Comment
793.7Aue, Guidoni, et al., 2000Experimental literature data re-evaluated by the authors using ab initio protonation entropies; MM
790.5 ± 1.1Fernandez, 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) (kJ/mol) Reference Comment
766.9Aue, Guidoni, et al., 2000Experimental literature data re-evaluated by the authors using ab initio protonation entropies; MM
771.3 ± 1.4Fernandez, 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 (J/mol*K) Reference Comment
44.2Fernandez, 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
8.52 ± 0.01EQLias and Ausloos, 1978LLK
8.44PEBock, Kaim, et al., 1978LLK
8.80 ± 0.05EILoudon and Mazengo, 1974LLK
8.37 ± 0.02PEMaier and Turner, 1973LLK
8.52CTSKinoshita, 1962RDSH
8.445PIBralsford, Harris, et al., 1960RDSH
8.44 ± 0.02PIVilesov and Terenin, 1957RDSH
8.445 ± 0.015PIWatanabe, 1954RDSH
8.48SHammond, Price, et al., 1950RDSH
8.44PEHowell, Goncalves, et al., 1984Vertical value; LBLHLM
8.43PEKoenig, Tuttle, et al., 1974Vertical value; LLK
8.6 ± 0.03PEKlessinger, 1972Vertical value; LLK

Appearance energy determinations

Ion AE (eV) Other Products MethodReferenceComment
C5H5+16.3 ± 0.2C2H2+CH3EITajima and Tsuchiya, 1973LLK
C7H7+11.5 ± 0.3?EIMcLafferty and Winkler, 1974LLK
C7H7+11.9 ± 0.2CH3EILoudon and Mazengo, 1974LLK
C7H7+11.05 ± 0.05CH3PIAkopyan and Vilesov, 1968RDSH
C7H7+11.3 ± 0.1CH3EINounou, 1966RDSH
C8H9+12.1 ± 0.2HEILoudon and Mazengo, 1974LLK
C8H9+11.35 ± 0.05HPIAkopyan and Vilesov, 1968RDSH
C8H9+11.9 ± 0.1HEITait, Shannon, et al., 1962RDSH

De-protonation reactions

C8H9- + Hydrogen cation = p-Xylene

By formula: C8H9- + H+ = C8H10

Quantity Value Units Method Reference Comment
Δr1598. ± 10.kJ/molG+TSBartmess, Scott, et al., 1979gas phase; value altered from reference due to change in acidity scale; B
Quantity Value Units Method Reference Comment
Δr1568. ± 9.6kJ/molIMREBartmess, Scott, et al., 1979gas 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]

Hammer, Diri, et al., 2003
Hammer, N.I.; Diri, K.; Jordan, K.D.; Desfrancois, C.; Compton, R.N., Dipole-bound anions of carbonyl, nitrile, and sulfoxide containing molecules, J. Chem. Phys., 2003, 119, 7, 3650-3660, https://doi.org/10.1063/1.1590959 . [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]

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]

Bock, Kaim, et al., 1978
Bock, H.; Kaim, W.; Rohwer, H.E., Die hyperkonjugative Stabilisierung von p-Xylol-Radikalkationen durch (H3C)3Si-Substituenten, Chem. Ber., 1978, 111, 3573. [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]

Kinoshita, 1962
Kinoshita, M., The absorption spectra of the molecular complexes of aromatic compounds with p-bromanil, Bull. Chem. Soc. Japan, 1962, 35, 1609. [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]

Vilesov and Terenin, 1957
Vilesov, F.I.; Terenin, A.N., The photoionization of the vapors of certain organic compounds, Dokl. Akad. Nauk SSSR, 1957, 115, 744, In original 539. [all data]

Watanabe, 1954
Watanabe, K., Photoionization and total absorption cross section of gases. I. Ionization potentials of several molecules. Cross sections of NH3 and NO, J. Chem. Phys., 1954, 22, 1564. [all data]

Hammond, Price, et al., 1950
Hammond, V.J.; Price, W.C.; Teegan, J.P.; Walsh, A.D., The absorption spectra of some substituted benzenes and naphthalenes in the vacuum ultra-violet, Faraday Discuss. Chem. Soc., 1950, 9, 53. [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 π-complexes with metals. Comparison of the standard oxidation potentials and vertical ionization potentials, J. Am. Chem. Soc., 1984, 106, 3968. [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]

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

Tajima and Tsuchiya, 1973
Tajima, S.; Tsuchiya, T., Energetics consideration of C5H5+ ions produced from various precursors by electron impact, Bull. Chem. Soc. Jpn., 1973, 46, 3291. [all data]

McLafferty and Winkler, 1974
McLafferty, F.W.; Winkler, J., Gaseous tropylium, benzyl, tolyl, and norbornadienyl cations, J. Am. Chem. Soc., 1974, 96, 5182. [all data]

Akopyan and Vilesov, 1968
Akopyan, M.E.; Vilesov, F.I., Mass-spectrometric investigation of the photo-ionization of benzene and its methyl derivatives, Khim. Vysokikh Energ., 1968, 2, 107, In original 89. [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]

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]


Notes

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