Benzyne


Reaction thermochemistry 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

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Individual Reactions

benzynide anion + Hydrogen cation = Benzyne

By formula: C6H3- + H+ = C6H4

Quantity Value Units Method Reference Comment
Δr1584. ± 13.kJ/molG+TSGuo and Grabowski, 1991gas phase; Acidity between MeOH and tBuOH, comparable to EtOH
Quantity Value Units Method Reference Comment
Δr1552. ± 13.kJ/molIMRBGuo and Grabowski, 1991gas phase; Acidity between MeOH and tBuOH, comparable to EtOH
Δr1556. ± 21.kJ/molIMRBGronert and DePuy, 1989gas phase

(CAS Reg. No. 72863-53-7 • 4294967295Benzyne) + Benzyne = CAS Reg. No. 72863-53-7

By formula: (CAS Reg. No. 72863-53-7 • 4294967295C6H4) + C6H4 = CAS Reg. No. 72863-53-7

Quantity Value Units Method Reference Comment
Δr82. ± 17.kJ/molN/AAndrade and Riveros, 1996gas phase
Δr70. ± 15.kJ/molTherWenthold and Squires, 1995gas phase
Δr66. ± 13.kJ/molCIDTWenthold, Paulino, et al., 1991gas phase; Between PhF, furan

(CAS Reg. No. 77748-26-6 • 4294967295Benzyne) + Benzyne = CAS Reg. No. 77748-26-6

By formula: (CAS Reg. No. 77748-26-6 • 4294967295C6H4) + C6H4 = CAS Reg. No. 77748-26-6

Quantity Value Units Method Reference Comment
Δr226. ± 18.kJ/molN/AMeot-ner and Kafafi, 1988gas phase; anchored to 88MEO scale, not the "87 acidity scale". The Kiefer, Zhang, et al., 1997 BDE is for ortho.

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
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
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 C6H4+ (ion structure unspecified)

Quantity Value Units Method Reference Comment
Proton affinity (review)841.kJ/molN/AHunter and Lias, 1998HL
Quantity Value Units Method Reference Comment
Gas basicity808.5kJ/molN/AHunter and Lias, 1998HL

Electron affinity determinations

EA (eV) Method Reference Comment
1.2650 ± 0.0080LPESWenthold, Squires, et al., 1998Triplet state 3.8±0.5 kcal/mol up.; B
0.5640 ± 0.0070LPESWenthold, Squires, et al., 1998Triplet state 37.5±0.3 kcal/mol up.; B
1.249 ± 0.022CIDTWenthold, Hu, et al., 1996B
0.5594 ± 0.0087CIDTWenthold, Hu, et al., 1996B
0.560 ± 0.010LPESLeopold, Miller, et al., 1986B

Ionization energy determinations

IE (eV) Method Reference Comment
9.03 ± 0.05PEZhang and Chen, 1992LL
9.24PEDewar and Tien, 1985LBLHLM
8.95ESTRosenstock, Stockbauer, et al., 1980LLK
9.8 ± 0.2EIGrutzmacher and Hubner, 1969RDSH
9.5 ± 0.2EIGrutzmacher and Lohmann, 1967RDSH

De-protonation reactions

benzynide anion + Hydrogen cation = Benzyne

By formula: C6H3- + H+ = C6H4

Quantity Value Units Method Reference Comment
Δr1584. ± 13.kJ/molG+TSGuo and Grabowski, 1991gas phase; Acidity between MeOH and tBuOH, comparable to EtOH; B
Quantity Value Units Method Reference Comment
Δr1552. ± 13.kJ/molIMRBGuo and Grabowski, 1991gas phase; Acidity between MeOH and tBuOH, comparable to EtOH; B
Δr1556. ± 21.kJ/molIMRBGronert and DePuy, 1989gas phase; B

References

Go To: Top, Reaction thermochemistry data, 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.

Guo and Grabowski, 1991
Guo, Y.L.; Grabowski, J.J., Reactions of the Benzyne Radical Anion in the Gas Phase, the Acidity of the Phenyl Radical, and the Heat of Formation of ortho-Benzyne, J. Am. Chem. Soc., 1991, 113, 16, 5923, https://doi.org/10.1021/ja00016a001 . [all data]

Gronert and DePuy, 1989
Gronert, S.; DePuy, C.H., The Dehydrophenyl Anion and the Gas Phase Ion Chemistry of Benzyne, J. Am. Chem. Soc., 1989, 111, 26, 9253, https://doi.org/10.1021/ja00208a032 . [all data]

Andrade and Riveros, 1996
Andrade, P.B.M.; Riveros, J.M., Relative Gas-phase Acidities of Fluoro- and Chlorobenzene, J. Mass Spectrom., 1996, 31, 7, 767, https://doi.org/10.1002/(SICI)1096-9888(199607)31:7<767::AID-JMS345>3.0.CO;2-Q . [all data]

Wenthold and Squires, 1995
Wenthold, P.G.; Squires, R.R., Determination of the gas-phase acidities of halogen-substituted aromatic compounds using the silane-cleavage method, J. Mass Spectrom., 1995, 30, 1, 17, https://doi.org/10.1002/jms.1190300105 . [all data]

Wenthold, Paulino, et al., 1991
Wenthold, P.G.; Paulino, J.A.; Squires, R.R., The Absolute Heats of Formation of ortho-Benzyne, meta-Benzyne, and para-Benzyne, J. Am. Chem. Soc., 1991, 113, 19, 7414, https://doi.org/10.1021/ja00019a044 . [all data]

Meot-ner and Kafafi, 1988
Meot-ner, M.; Kafafi, S.A., Carbon Acidities of Aromatic Compounds, J. Am. Chem. Soc., 1988, 110, 19, 6297, https://doi.org/10.1021/ja00227a003 . [all data]

Kiefer, Zhang, et al., 1997
Kiefer, J.H.; Zhang, Q.; Kern, R.D.; Yao, J.; Jursic, B., Pyrolysis of Aromatic Azines: Pyrazine, Pyrimidine, and Pyridine, J. Phys. Chem. A, 1997, 101, 38, 7061, https://doi.org/10.1021/jp970211z . [all data]

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]

Wenthold, Squires, et al., 1998
Wenthold, P.G.; Squires, R.R.; Lineberger, W.C., Ultraviolet photoelectron spectroscopy of the o-, m-, and p-benzyne negative ions. Electron affinities and singlet-triplet splittings for o-, m-, and p-benzyne, J. Am. Chem. Soc., 1998, 120, 21, 5279-5290, https://doi.org/10.1021/ja9803355 . [all data]

Wenthold, Hu, et al., 1996
Wenthold, P.G.; Hu, J.; Squires, R.R., o-, m-, and p-Benzyne Negative Ions in the Gas Phase: Synthesis, Authentication, and Thermochemistry, J. Am. Chem. Soc., 1996, 118, 47, 11865, https://doi.org/10.1021/ja960663+ . [all data]

Leopold, Miller, et al., 1986
Leopold, D.G.; Miller, A.G.; Lineberger, W.C., Determination of the singlet-triplet splitting and electron affinity of, o-benzyne by negative ion photoelectron spectroscopy, J. Am. Chem. Soc., 1986, 108, 1379. [all data]

Zhang and Chen, 1992
Zhang, X.; Chen, P., Photoelectron spectrum of o-benzyne. Ionization potentials as a measure of singlet-triplet gaps, J. Am. Chem. Soc., 1992, 114, 3147. [all data]

Dewar and Tien, 1985
Dewar, M.J.S.; Tien, T.-P., Photoelectron spectrum of benzyne, J. Chem. Soc., Chem. Commun., 1985, 1243. [all data]

Rosenstock, Stockbauer, et al., 1980
Rosenstock, H.M.; Stockbauer, R.; Parr, A.C., Photoelectron-photoion coincidence study of benzonitrile, J. Chim. Phys., 1980, 77, 745. [all data]

Grutzmacher and Hubner, 1969
Grutzmacher, H.-F.; Hubner, J., Massenspektrometrie instabiler molekule. III: Nachweis und untersuchungen zur stabilitat chlorsubstituierter dehydrobenzole in der gasphase, Org. Mass Spectrom., 1969, 2, 649. [all data]

Grutzmacher and Lohmann, 1967
Grutzmacher, H.-F.; Lohmann, J., Massenspektrometrie instabiler organischer Molekule. I. Ionisations-potential und Bildungsenthalpie von Dehydrobenzol, Ann. Chem., 1967, 705, 81. [all data]


Notes

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