Benzene, hexamethyl-

• Formula: C₁₂H₁₈
• Molecular weight: 162.2713
• IUPAC Standard InChI: InChI=1S/C12H18/c1-7-8(2)10(4)12(6)11(5)9(7)3/h1-6H3 Copy

  
• IUPAC Standard InChIKey: YUWFEBAXEOLKSG-UHFFFAOYSA-N Copy
• CAS Registry Number: 87-85-4
• Chemical structure:
  This structure is also available as a 2d Mol file or as a computed 3d SD file
  The 3d structure may be viewed using Java or Javascript.
• Isotopologues:
  • Hexamethylbenzene, deuterated
• Other names: Hexamethylbenzene; Mellitene; 1,2,3,4,5,6-Hexamethylbenzene
• Permanent link for this species. Use this link for bookmarking this species for future reference.
• Information on this page:
  • Condensed phase thermochemistry data
  • Phase change data
  • Reaction thermochemistry data
  • Gas phase ion energetics data
  • Ion clustering data
  • References
  • Notes
• Other data available:
  • Gas phase thermochemistry data
  • IR Spectrum
  • Mass spectrum (electron ionization)
  • UV/Visible spectrum
  • Gas Chromatography
• Options:
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• NIST / TRC Web Thermo Tables, professional edition (thermophysical and thermochemical data)

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Condensed 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 as indicated in comments:
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
DH - Eugene S. Domalski and Elizabeth D. Hearing

Constant pressure heat capacity of liquid

Constant pressure heat capacity of solid

Phase change 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 as indicated in comments:
BS - Robert L. Brown and Stephen E. Stein
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director
AC - William E. Acree, Jr., James S. Chickos
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
DRB - Donald R. Burgess, Jr.
CAL - James S. Chickos, William E. Acree, Jr., Joel F. Liebman, Students of Chem 202 (Introduction to the Literature of Chemistry), University of Missouri -- St. Louis
DH - Eugene S. Domalski and Elizabeth D. Hearing

Enthalpy of vaporization

Enthalpy of sublimation

Enthalpy of fusion

Entropy of fusion

Temperature of phase transition

Enthalpy of phase transition

Entropy of phase transition

Reaction thermochemistry data

Go To: Top, Condensed phase thermochemistry data, Phase change data, Gas phase ion energetics data, Ion clustering 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 as indicated in comments:
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
M - Michael M. Meot-Ner (Mautner) and Sharon G. Lias

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

=

By formula: C₁₂H₁₈ = C₁₂H₁₈

=

By formula: C₁₂H₁₈ = C₁₂H₁₈

C₆H₇N⁺ +  = (C₆H₇N⁺ • )

By formula: C₆H₇N⁺ + C₁₂H₁₈ = (C₆H₇N⁺ • C₁₂H₁₈)

Bond type: Charge transfer bond (positive ion)

=

By formula: C₁₂H₁₈ = C₁₂H₁₈

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:
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
B - John E. Bartmess

View reactions leading to C₁₂H₁₈⁺ (ion structure unspecified)

Electron affinity determinations

Ionization energy determinations

Ion clustering data

Go To: Top, Condensed phase thermochemistry data, Phase change 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: Michael M. Meot-Ner (Mautner) and Sharon G. Lias

Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. Searches may be limited to ion clustering reactions. A general reaction search form is also available.

Clustering reactions

C₆H₇N⁺ +  = (C₆H₇N⁺ • )

By formula: C₆H₇N⁺ + C₁₂H₁₈ = (C₆H₇N⁺ • C₁₂H₁₈)

Bond type: Charge transfer bond (positive ion)

References

Go To: Top, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, Gas phase ion energetics data, Ion clustering data, Notes

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

Oth, 1968
Oth, J.F.M., The kinetics and thermochemistry of the thermal rearrangement of hexamethylbicyclo[2.2.0]hexa-2,5-diene (hexamethyldewarbenzene) and of hexamethyltetracyclo[2.2.0,0(2,6).0(3,5)]hexane (hexamethylprismane), Chem. Ber., 1968, 47, 1185-1195. [all data]

Banse and Parks, 1933
Banse, H.; Parks, G.S., Thermal data on organic compounds. XII. The heats of combustion of nine hydrocarbons, J. Am. Chem. Soc., 1933, 55, 3223-3227. [all data]

Cox and Pilcher, 1970
Cox, J.D.; Pilcher, G., Thermochemistry of Organic and Organometallic Compounds, Academic Press, New York, 1970, 1-636. [all data]

Colomina, Jimenez, et al., 1989
Colomina, M.; Jimenez, P.; Roux, M.V.; Turrion, C., Thermochemical properties of 1,2,4,5-tetramethylbenzene, pentamethylbenzene, and hexamethylbenzene, J. Chem. Thermodyn., 1989, 21, 275-281. [all data]

Boned, Colomina, et al., 1964
Boned, M.L.; Colomina, M.; Perez-Ossorio, R.; Turrion, C., Investigaciones termoquimicas sobre los polimetilbencenos superiores, Anal. Fisc. Quim. B, 1964, 60, 459-468. [all data]

Parks, West, et al., 1946
Parks, G.S.; West, T.J.; Naylor, B.F.; Fujii, P.S.; McClaine, L.A., Thermal data on organic compounds. XXIII. Modern combustion data for fourteen hydrocarbons and five polyhydroxy alcohols, J. Am. Chem. Soc., 1946, 68, 2524-2527. [all data]

Holdiness, 1984
Holdiness, M.R., Resonance energy of hexaethylbenzene and hexamethylbenzene, Thermochim. Acta, 1984, 78, 435-436. [all data]

Atake, Gyoten, et al., 1982
Atake, T.; Gyoten, H.; Chihara, H., A concealed anomaly at 117.5 K in the heat capacity of hexamethylbenzene, J. Chem. Phys., 1982, 76(11), 5535-5540. [all data]

Frankosky and Aston, 1965
Frankosky, M.; Aston, J.G., The heat capacity and entropy of hexamethylbenzene from 13 to 340 K. An estimate of the internal rotation barrier, J. Phys. Chem., 1965, 69, 3126-3132. [all data]

Huffman, Parks, et al., 1930
Huffman, H.M.; Parks, G.S.; Daniels, A.C., Thermal data on organic compounds. VII. The heat capacities, entropies and free energies of twelve aromatic hydrocarbons, J. Am. Chem. Soc., 1930, 52, 1547-1558. [all data]

Kurbatov, 1947
Kurbatov, V.Ya., Specific heat of liquids. I. Specific heat of benzenoid hydrocarbons, Zhur. Obshch. Khim., 1947, 17, 1999-2003. [all data]

Momotani, Suga, et al., 1956
Momotani, M.; Suga, H.; Seki, S.; Nitta, I., Phase transitions in crystals composed of organic molecules with methyl groups at the molecular periperies, Proceed. National Academy of Sci. (India), XXV(Section A, part, 1956, II), 74-82. [all data]

Spaght, Thomas, et al., 1932
Spaght, M.E.; Thomas, S.B.; Parks, G.S., Some heat capacity data on organic compounds obtained with a radiation calorimeter, J. Phys. Chem., 1932, 36, 882-888. [all data]

Weast and Grasselli, 1989
CRC Handbook of Data on Organic Compounds, 2nd Editon, Weast,R.C and Grasselli, J.G., ed(s)., CRC Press, Inc., Boca Raton, FL, 1989, 1. [all data]

Cooper, Crowne, et al., 1967
Cooper, A.R.; Crowne, C.W.P.; Farrell, P.G., Gas-Liquid Chromatographic Studies of Electron-Donor-Acceptor Systems, Trans. Faraday Soc., 1967, 63, 447. [all data]

Tsonopoulos and Ambrose, 1995
Tsonopoulos, C.; Ambrose, D., Vapor-Liquid Critical Properties of Elements and Compounds. 3. Aromatic Hydrocarbons, J. Chem. Eng. Data, 1995, 40, 547-558. [all data]

Ambrose, Broderick, et al., 1974
Ambrose, D.; Broderick, B.E.; Townsend, R., The Critical Temperatures and Pressures of Thirty Organic Compounds, J. Appl. Chem. Biotechnol., 1974, 24, 359. [all data]

Guye and Mallet, 1902
Guye, P.A.; Mallet, E., Measurement of Critical Constants, Arch. Sci. Phys. Nat., 1902, 13, 274-296. [all data]

Zhao, Unhannanant, et al., 2008
Zhao, Hui; Unhannanant, Patamaporn; Hanshaw, William; Chickos, James S., Enthalpies of Vaporization and Vapor Pressures of Some Deuterated Hydrocarbons. Liquid-Vapor Pressure Isotope Effects, J. Chem. Eng. Data, 2008, 53, 7, 1545-1556, https://doi.org/10.1021/je800091s . [all data]

Stephenson and Malanowski, 1987
Stephenson, Richard M.; Malanowski, Stanislaw, Handbook of the Thermodynamics of Organic Compounds, 1987, https://doi.org/10.1007/978-94-009-3173-2 . [all data]

Ambrose, Lawrenson, et al., 1976
Ambrose, D.; Lawrenson, I.J.; Sprake, C.H.S., The vapour pressure of hexamethylbenzene, The Journal of Chemical Thermodynamics, 1976, 8, 5, 503-504, https://doi.org/10.1016/0021-9614(76)90071-9 . [all data]

Overberger, Steele, et al., 1969
Overberger, John E.; Steele, William A.; Aston, John G., The vapor pressure of hexamethylbenzene the standard entropy of hexamethylbenzene vapor and the barrier to internal rotation, The Journal of Chemical Thermodynamics, 1969, 1, 6, 535-542, https://doi.org/10.1016/0021-9614(69)90014-7 . [all data]

Domalski and Hearing, 1996
Domalski, Eugene S.; Hearing, Elizabeth D., Heat Capacities and Entropies of Organic Compounds in the Condensed Phase. Volume III, J. Phys. Chem. Ref. Data, 1996, 25, 1, 1, https://doi.org/10.1063/1.555985 . [all data]

Spaght, Thomas, et al., 1931
Spaght, M.E.; Thomas, S.B.; Parks, G.S., Some Heat-Capacity Data on Organic Compounds obtained with a Radiation Calorimeter, J. Phys. Chem., 1931, 36, 3, 882-888, https://doi.org/10.1021/j150333a009 . [all data]

Fujiwara, Inaba, et al., 1992
Fujiwara, T.; Inaba, A.; Atake, T.; Chihara, H., Thermodynamic properties of deuterated hexamethylbenzene and of its solid solutions with the hydrogenated analog. A large isotope effect on the phase transition at the temperature 117 K, J. Chem. Thermodynam., 1992, 24, 863-881. [all data]

Petropavlov, Tsygankova, et al., 1988
Petropavlov, N.N.; Tsygankova, I.G.; Teslenko, L.A., Microcalorimetric investigation of polymorphic transitions in organic crystals, Sov. Phys. Crystallogr., 1988, 33(6), 853-855. [all data]

Yoshimoto, Fujiwara, et al., 1985
Yoshimoto, Y.; Fujiwara, T.; Atake, T.; Chihara, H., Solid-solid transition in hexamethylbenzene that depends on thermal history, Chem. Lett., 1985, (9), 1347-1350. [all data]

Adam and Chang, 1969
Adam, W.; Chang, J.C., Kinetics and thermochemistry of valence isomerization by differential scanning calorimetry: the case of hexamethylprismane and hexamethyldewarbenzene, Int. J. Chem. Kinet., 1969, 1, 487-492. [all data]

Oth, 1969
Oth, J.F.M., The kinetics and thermochemistry of the thermal rearrangement of hexamethyl(Dewar benzene) and of hexamethylprismane, Angew. Chem. Int. Ed. Engl., 1969, 7, 646. [all data]

Meot-Ner (Mautner) and El-Shall, 1986
Meot-Ner (Mautner), M.; El-Shall, M.S., Ionic Charge Transfer Complexes. 1. Cationic Complexes with Delocalized and Partially Localized pi Systems, J. Am. Chem. Soc., 1986, 108, 15, 4386, https://doi.org/10.1021/ja00275a026 . [all data]

Childs and Mulholland, 1983
Childs, R.F.; Mulholland, D.L., Thermochemical relationships between some bicyclohexenyl and benzenium cations, J. Am. Chem. Soc., 1983, 105, 96-99. [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]

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Wojnarovits, L.; Foldiak, G., Electron capture detection of aromatic hydrocarbons, J. Chromatogr. Sci., 1981, 206, 511. [all data]

Chen and Wentworth, 1989
Chen, E.C.M.; Wentworth, W.E., Experimental Determination of Electron Affinities of Organic Molecules, Mol. Cryst. Liq. Cryst., 1989, 171, 271. [all data]

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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]

Kuznesof, Stafford, et al., 1967
Kuznesof, P.M.; Stafford, F.E.; Shriver, D.F., Electron impact ionization potentials of methyl-substituted borazines, J. Phys. Chem., 1967, 71, 1939. [all data]

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Vilesov, F.I., Photoionisation of organic vapours in the vacuum ultra-violet, Zh. Fiz. Khim., 1961, 35, 2010, In original 986. [all data]

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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]

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Foster, R., Ionization potentials of electron donors, Nature (London), 1959, 183, 1253. [all data]

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Briegleb, G.; Czekalla, J., Die Bestimmung von lonisierungsenergien aus den Spektren von Elektronenubergangskomplexen, Z.Elektrochem., 1959, 63, 6. [all data]

Kovac, Mohraz, et al., 1980
Kovac, B.; Mohraz, M.; Heilbronner, E.; Boekelheide, V.; Hopf, H., Photoelectron spectra of the cyclophanes, J. Am. Chem. Soc., 1980, 102, 4314. [all data]

Notes

Go To: Top, Condensed phase thermochemistry data, Phase change data, Reaction thermochemistry data, Gas phase ion energetics data, Ion clustering data, References

• Symbols used in this document:
  

  Cp,liquid	Constant pressure heat capacity of liquid
  Cp,solid	Constant pressure heat capacity of solid
  EA	Electron affinity
  IE (evaluated)	Recommended ionization energy
  S°solid,1 bar	Entropy of solid at standard conditions (1 bar)
  Tboil	Boiling point
  Tc	Critical temperature
  Tfus	Fusion (melting) point
  Ttrs	Temperature of phase transition
  ΔHtrs	Enthalpy of phase transition
  ΔStrs	Entropy of phase transition
  ΔcH°liquid	Enthalpy of combustion of liquid at standard conditions
  ΔcH°solid	Enthalpy of combustion of solid at standard conditions
  ΔfH°liquid	Enthalpy of formation of liquid at standard conditions
  ΔfH°solid	Enthalpy of formation of solid at standard conditions
  ΔfusH	Enthalpy of fusion
  ΔfusS	Entropy of fusion
  ΔrH°	Enthalpy of reaction at standard conditions
  ΔrS°	Entropy of reaction at standard conditions
  ΔsubH	Enthalpy of sublimation
  ΔsubH°	Enthalpy of sublimation at standard conditions
  ΔvapH	Enthalpy of vaporization
  ΔvapH°	Enthalpy of vaporization at standard conditions

• Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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