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Benzyne


Gas phase 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: Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein

Quantity Value Units Method Reference Comment
Deltafgas105. ± 2.4kcal/molIonRiveros, Ingeman, et al., 1991Bracketing technique
Deltafgas106. ± 3.kcal/molIonWenthold, Paulino, et al., 1991collision-induced dissociation
Deltafgas118. ± 5.kcal/molIonPollack and Hehre, 1980 

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

Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. A general reaction search form is also available. Future versions of this site may rely on reaction search pages in place of the enumerated reaction displays seen below.

Individual Reactions

benzynide anion + Hydrogen cation = Benzyne

By formula: C6H3- + H+ = C6H4

Quantity Value Units Method Reference Comment
Deltar378.7 ± 3.1kcal/molG+TSGuo and Grabowski, 1991gas phase; Acidity between MeOH and tBuOH, comparable to EtOH
Quantity Value Units Method Reference Comment
Deltar371.0 ± 3.0kcal/molIMRBGuo and Grabowski, 1991gas phase; Acidity between MeOH and tBuOH, comparable to EtOH
Deltar372.0 ± 5.0kcal/molIMRBGronert and DePuy, 1989gas phase

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

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

Quantity Value Units Method Reference Comment
Deltar19.5 ± 4.1kcal/molN/AAndrade and Riveros, 1996gas phase
Deltar16.7 ± 3.7kcal/molTherWenthold and Squires, 1995gas phase
Deltar15.7 ± 3.0kcal/molCIDTWenthold, Paulino, et al., 1991, 2gas phase; Between PhF, furan

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

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

Quantity Value Units Method Reference Comment
Deltar54.1 ± 4.4kcal/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

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Vibrational and/or electronic energy levels, References, Notes

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)201.kcal/molN/AHunter and Lias, 1998HL
Quantity Value Units Method Reference Comment
Gas basicity193.2kcal/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
Deltar378.7 ± 3.1kcal/molG+TSGuo and Grabowski, 1991gas phase; Acidity between MeOH and tBuOH, comparable to EtOH; B
Quantity Value Units Method Reference Comment
Deltar371.0 ± 3.0kcal/molIMRBGuo and Grabowski, 1991gas phase; Acidity between MeOH and tBuOH, comparable to EtOH; B
Deltar372.0 ± 5.0kcal/molIMRBGronert and DePuy, 1989gas phase; B

Vibrational and/or electronic energy levels

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Gas phase ion energetics data, References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled by: Marilyn E. Jacox

State:   ?


 Energy 
 (cm-1
 Med.   Transition   «lambda»min 
 (nm) 
 «lambda»max 
 (nm) 
 References

Tx = 50200 Ar Munzel and Schweig, 1988
Simon, Munzel, et al., 1990

State:   ?


 Energy 
 (cm-1
 Med.   Transition   «lambda»min 
 (nm) 
 «lambda»max 
 (nm) 
 References

Tx = 40600 Ar Munzel and Schweig, 1988
Simon, Munzel, et al., 1990

State:   ?


 Energy 
 (cm-1
 Med.   Transition   «lambda»min 
 (nm) 
 «lambda»max 
 (nm) 
 References

Tx = 28730 Ne Radziszewski, Hess, et al., 1992

State:   ?


 Energy 
 (cm-1
 Med.   Transition   «lambda»min 
 (nm) 
 «lambda»max 
 (nm) 
 References

Tx = 26300 Ar Munzel and Schweig, 1988

State:   a


 Energy 
 (cm-1
 Med.   Transition   «lambda»min 
 (nm) 
 «lambda»max 
 (nm) 
 References

To = 13140 ± 50 gas Leopold, Stevens-Miller, et al., 1986
Wenthold, Squires, et al., 1998, 2


Vib. 
sym. 
 No.   Approximate 
 type of mode 
 cm-1   Med.   Method   References

a1 1520 ± 40 gas PE Wenthold, Squires, et al., 1998, 2
1395 ± 30 gas PE Leopold, Stevens-Miller, et al., 1986
Wenthold, Squires, et al., 1998, 2
1275 ± 30 gas PE Wenthold, Squires, et al., 1998, 2
560 ± 20 gas PE Leopold, Stevens-Miller, et al., 1986
Wenthold, Squires, et al., 1998, 2

State:   X


Vib. 
sym. 
 No.   Approximate 
 type of mode 
 cm-1   Med.   Method   References

a1 1 CH stretch 3094 w m Ne IR Radziszewski, Hess, et al., 1992
1 CH stretch 3088 N2 IR Dunkin and MacDonald, 1979
2 CH stretch 3071 w Ne IR Radziszewski, Hess, et al., 1992
3 CC stretch 1860 ± 15 gas PE Leopold, Stevens-Miller, et al., 1986
Wenthold, Squires, et al., 1998, 2
3 CC stretch 1846 w Ne IR Radziszewski, Hess, et al., 1992
4 Mixed 1415 w Ne IR Radziszewski, Hess, et al., 1992
5 Mixed 1271 w Ne IR Radziszewski, Hess, et al., 1992
6 CH deform. 1055 w m Ne IR Radziszewski, Hess, et al., 1992
6 CH deform. 1053 m Ar IR Chapman, Mattes, et al., 1973
6 CH deform. 1056 N2 IR Dunkin and MacDonald, 1979
Nam and Leroi, 1987
7 Ring stretch 1010 ± 40 gas PE Leopold, Stevens-Miller, et al., 1986
Wenthold, Squires, et al., 1998, 2
7 Ring stretch 1039 m Ne IR Radziszewski, Hess, et al., 1992
7 Ring stretch 1038 m Ar IR Chapman, Mattes, et al., 1973
7 Ring stretch 1039 N2 IR Dunkin and MacDonald, 1979
Nam and Leroi, 1987
8 Ring stretch 982 w m Ne IR Radziszewski, Hess, et al., 1992
9 Ring deform. 600 ± 15 gas PE Leopold, Stevens-Miller, et al., 1986
Wenthold, Squires, et al., 1998, 2
9 Ring deform. 589 w Ne IR Radziszewski, Hess, et al., 1992
b1 14 CH wag 838 w Ne IR Radziszewski, Hess, et al., 1992
15 CH wag 737 s Ne IR Radziszewski, Hess, et al., 1992
15 CH wag 736 vs Ar IR Chapman, Mattes, et al., 1973
15 CH wag 743 N2 IR Dunkin and MacDonald, 1979
Nam and Leroi, 1987
16 Ring torsion 388 w m Ne IR Radziszewski, Hess, et al., 1992
b2 17 CH stretch 3086 m Ne IR Radziszewski, Hess, et al., 1992
18 CH stretch 3049 w Ne IR Radziszewski, Hess, et al., 1992
19 Ring stretch 1451 m Ne IR Radziszewski, Hess, et al., 1992
19 Ring stretch 1451 m Ar IR Chapman, Mattes, et al., 1973
19 Ring stretch 1448 N2 IR Dunkin and MacDonald, 1979
Nam and Leroi, 1987
20 Mixed 1394 w m Ne IR Radziszewski, Hess, et al., 1992
20 Mixed 1395 N2 IR Nam and Leroi, 1987
20 Mixed 1355 N2 IR Nam and Leroi, 1987
21 Mixed 1307 w Ne IR Radziszewski, Hess, et al., 1992
22 Mixed 1094 w Ne IR Radziszewski, Hess, et al., 1992
23 Ring deform. 849 m s Ne IR Radziszewski, Hess, et al., 1992
23 Ring deform. 849 s Ar IR Chapman, Mattes, et al., 1973
23 Ring deform. 847 N2 IR Dunkin and MacDonald, 1979
Nam and Leroi, 1987
24 Ring deform. 472 vs Ne IR Radziszewski, Hess, et al., 1992
24 Ring deform. 469 vs Ar IR Chapman, Mattes, et al., 1973
24 Ring deform. 472 N2 IR Dunkin and MacDonald, 1979
Nam and Leroi, 1987

Additional references: Jacox, 1994, page 386; Jacox, 2003, page 364; Brown, Godfrey, et al., 1986; Robertson, Godfrey, et al., 2003; Kukolich, Tanjaroon, et al., 2003; Kukolich, McCarthy, et al., 2004

Notes

wWeak
mMedium
sStrong
vsVery strong
oEnergy separation between the v = 0 levels of the excited and electronic ground states.
xEnergy separation between the band maximum of the excited electronic state and the v = 0 level of the ground state.

References

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Gas phase ion energetics data, Vibrational and/or electronic energy levels, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Riveros, Ingeman, et al., 1991
Riveros, J.M.; Ingeman, S.; Nibbering, N.M.M., Formation of gas-phase solvated Br-and I- ion/molecule reactions of halobenzenes. Revised heat of formation of benzyne, J. Am. Chem. Soc., 1991, 113, 1053. [all data]

Wenthold, Paulino, et al., 1991
Wenthold, P.G.; Paulino, J.A.; Squires, R.R., The absolute heats of formation of o-,m-, and p-benzyne, J. Am. Chem. Soc., 1991, 113, 7414-7415. [all data]

Pollack and Hehre, 1980
Pollack, S.K.; Hehre, W.J., Determination of the heat of formation of ortho-benzyne by ion cyclotron resonance spectroscopy, Tetrahedron Lett., 1980, 21, 2483-2486. [all data]

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, 2
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]

Munzel and Schweig, 1988
Munzel, N.; Schweig, A., UV/VIS absorption spectrum, geometry and electronic structure of transient o-benzyne, Chem. Phys. Lett., 1988, 147, 2-3, 192, https://doi.org/10.1016/0009-2614(88)85082-6 . [all data]

Simon, Munzel, et al., 1990
Simon, J.G.G.; Munzel, N.; Schweig, A., Matrix isolation photochemistry: photoequilibrium between transient o-benzyne, carbon monoxide and transient cyclopentadienylideneketene in an argon matrix, Chem. Phys. Lett., 1990, 170, 2-3, 187, https://doi.org/10.1016/0009-2614(90)87113-6 . [all data]

Radziszewski, Hess, et al., 1992
Radziszewski, J.G.; Hess, B.A., Jr.; Zahradnik, R., Infrared spectrum of o-benzyne: experiment and theory, J. Am. Chem. Soc., 1992, 114, 1, 52, https://doi.org/10.1021/ja00027a007 . [all data]

Leopold, Stevens-Miller, et al., 1986
Leopold, D.G.; Stevens-Miller, A.E.; Linebergr, 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, 7, 1379, https://doi.org/10.1021/ja00267a003 . [all data]

Wenthold, Squires, et al., 1998, 2
Wenthold, P.G.; Squires, R.R.; Lineberger, W.C., Ultraviolet Photoelectron Spectroscopy of the, J. Am. Chem. Soc., 1998, 120, 21, 5279, https://doi.org/10.1021/ja9803355 . [all data]

Dunkin and MacDonald, 1979
Dunkin, I.R.; MacDonald, J.G., J. Chem. Soc., 1979, Chem. Commun. 772. [all data]

Chapman, Mattes, et al., 1973
Chapman, O.L.; Mattes, K.; McIntosh, C.L.; Pacansky, J.; Calder, G.V.; Orr, G., Photochemical transformations. LII. Benzyne, J. Am. Chem. Soc., 1973, 95, 18, 6134, https://doi.org/10.1021/ja00799a060 . [all data]

Nam and Leroi, 1987
Nam, H.-H.; Leroi, G.E., On the vibrational spectrum of matrix isolated o-benzyne, J. Mol. Struct., 1987, 157, 1-3, 301, https://doi.org/10.1016/0022-2860(87)87100-4 . [all data]

Jacox, 1994
Jacox, M.E., Vibrational and electronic energy levels of polyatomic transient molecules, American Chemical Society, Washington, DC, 1994, 464. [all data]

Jacox, 2003
Jacox, M.E., Vibrational and electronic energy levels of polyatomic transient molecules: supplement B, J. Phys. Chem. Ref. Data, 2003, 32, 1, 1-441, https://doi.org/10.1063/1.1497629 . [all data]

Brown, Godfrey, et al., 1986
Brown, R.D.; Godfrey, P.D.; Rodler, M., Microwave spectrum of benzyne, J. Am. Chem. Soc., 1986, 108, 6, 1296, https://doi.org/10.1021/ja00266a028 . [all data]

Robertson, Godfrey, et al., 2003
Robertson, E.G.; Godfrey, P.D.; McNaughton, D., The microwave spectrum of o-benzyne measured in a novel Stark modulated spectrometer for transient molecules, J. Mol. Spectrosc., 2003, 217, 1, 123, https://doi.org/10.1016/S0022-2852(02)00021-8 . [all data]

Kukolich, Tanjaroon, et al., 2003
Kukolich, S.G.; Tanjaroon, C.; McCarthy, M.C.; Thaddeus, P., Microwave spectrum of o-benzyne produced in a discharge nozzle, J. Chem. Phys., 2003, 119, 8, 4353, https://doi.org/10.1063/1.1593015 . [all data]

Kukolich, McCarthy, et al., 2004
Kukolich, S.G.; McCarthy, M.C.; Thaddeus, P., Molecular Structure of, J. Phys. Chem. A, 2004, 108, 14, 2645, https://doi.org/10.1021/jp031344p . [all data]


Notes

Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, Gas phase ion energetics data, Vibrational and/or electronic energy levels, References