Dewar benzene, hexamethyl-
- Formula: C12H18
- Molecular weight: 162.2713
- IUPAC Standard InChI: InChI=1S/C12H18/c1-7-8(2)12(6)10(4)9(3)11(7,12)5/h1-6H3
- IUPAC Standard InChIKey: RVNQQZMIWZPGNA-UHFFFAOYSA-N
- CAS Registry Number: 7641-77-2
- 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. - Other names: Bicyclo[2.2.0]hexa-2,5-diene, 1,2,3,4,5,6-hexamethyl-; Hexamethyl Dewar benzene; Hexamethylbicyclo[2.2.0]hexa-2,5-diene; 1,2,3,4,5,6-Hexamethylbicyclo[2.2.0]hexa-2,5-diene; Bicyclo(2.2.0)hexa-2,5-diene, hexamethyl-; 2-Butin hexamethyl-dewar-benzol; Hexamethyl-bicyclo(2.2.0)hexa-2,5-dien; 1,2,3,4,5,6-hexamethylbicyclo(2,2,0)hexa-2,5-diene
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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 by: Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔfH°liquid | -21.6 | kcal/mol | Ccb | Schafer and Hellmann, 1967 | |
| Quantity | Value | Units | Method | Reference | Comment |
| ΔcH°liquid | -1765. ± 1.1 | kcal/mol | Ccb | Schafer and Hellmann, 1967 | Corresponding ΔfHºliquid = 22. kcal/mol (simple calculation by NIST; no Washburn corrections) |
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: Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
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
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔrH° | -56.2 ± 0.6 | kcal/mol | Cm | Adam and Chang, 1969 | liquid phase; solvent: Pure phase |
| ΔrH° | -59.5 | kcal/mol | Eqk | Oth, 1968 | liquid phase; Heat of isomerization, see Oth, 1969 |
=
By formula: C12H18 = C12H18
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔrH° | -55.7 ± 0.6 | kcal/mol | Cm | Adam and Chang, 1969 | liquid phase; solvent: Pure phase; Heat of isomerization |
Gas phase ion energetics data
Go To: Top, Condensed phase thermochemistry data, Reaction thermochemistry 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:
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
View reactions leading to C12H18+ (ion structure unspecified)
Ionization energy determinations
| IE (eV) | Method | Reference | Comment |
|---|---|---|---|
| 7.83 | PE | Bougeard, Schrader, et al., 1974 | Vertical value; LLK |
| 7.92 | PE | Marschner, Juds, et al., 1973 | Vertical value; LLK |
References
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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Schafer and Hellmann, 1967
Schafer, W.; Hellmann, H.,
Hexamethyl-Dewar-Benzol (Hexamethyl-bicyclo[2.2.0]hexa-2,5-dien),
Angew. Chem., 1967, 79, 566-573. [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, 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]
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]
Bougeard, Schrader, et al., 1974
Bougeard, D.; Schrader, B.; Bleckmann, P.; Plesser, T.,
Ramanspektroskopie und molekulstruktur. VII. Infrarot-, raman- und photoelektronenspektrum des hexamethyl-dewarbenzols; normalkoordinatenberechnung und untersuchung der π-elektronen-wechselwirkung,
Justus Liebigs Ann. Chem., 1974, 156, 137. [all data]
Marschner, Juds, et al., 1973
Marschner, F.; Juds, H.; Goetz, H.,
Zur homokonjugation im hexamethyl-dewar-benzol,
Tetrahedron Lett., 1973, 3983. [all data]
Notes
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- Symbols used in this document:
ΔcH°liquid Enthalpy of combustion of liquid at standard conditions ΔfH°liquid Enthalpy of formation of liquid at standard conditions ΔrH° Enthalpy of reaction at standard conditions - Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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