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) |
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 by: Robert L. Brown and Stephen E. Stein
Reduced pressure boiling point
| Tboil (K) | Pressure (atm) | Reference |
|---|---|---|
| 333.2 | 0.026 | Aldrich Chemical Company Inc., 1990 |
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
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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:
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 |
UV/Visible spectrum
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Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Spectrum
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Additional Data
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| Source | (editor), 1973 |
|---|---|
| Owner | INEP CP RAS, NIST OSRD Collection (C) 2007 copyright by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved. |
| Origin | INSTITUTE OF ENERGY PROBLEMS OF CHEMICAL PHYSICS, RAS |
| Source reference | RAS UV No. 18974 |
| Instrument | SF-16 |
| Boiling point | 43.0-45.0/ 15 mm |
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]
Aldrich Chemical Company Inc., 1990
Aldrich Chemical Company Inc.,
Catalog Handbook of Fine Chemicals, Aldrich Chemical Company, Inc., Milwaukee WI, 1990, 1. [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]
(editor), 1973
(editor), Koptyug V.A.,
Atlas of Spectra of Aromatic and Heterocyclic Compounds, 1973, 3, 75. [all data]
Notes
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- Symbols used in this document:
Tboil Boiling point 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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