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
- IUPAC Standard InChIKey: YUWFEBAXEOLKSG-UHFFFAOYSA-N
- 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:
- Other names: Hexamethylbenzene; Mellitene; 1,2,3,4,5,6-Hexamethylbenzene
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Condensed phase thermochemistry data
Go To: Top, 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
DH - Eugene S. Domalski and Elizabeth D. Hearing
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔfH°liquid | -33.94 | kcal/mol | Ccb | Oth, 1968 | ALS |
| Quantity | Value | Units | Method | Reference | Comment |
| ΔcH°liquid | -1705.2 ± 1.7 | kcal/mol | Ccb | Banse and Parks, 1933 | Reanalyzed by Cox and Pilcher, 1970, Original value = -1703.88 kcal/mol; Corresponding ΔfHºliquid = -38.25 kcal/mol (simple calculation by NIST; no Washburn corrections); ALS |
| Quantity | Value | Units | Method | Reference | Comment |
| ΔfH°solid | -38.81 ± 0.60 | kcal/mol | Ccb | Colomina, Jimenez, et al., 1989 | see Boned, Colomina, et al., 1964; ALS |
| ΔfH°solid | -39.03 ± 0.73 | kcal/mol | Ccb | Parks, West, et al., 1946 | Reanalyzed by Cox and Pilcher, 1970, Original value = -39.19 ± 0.02 kcal/mol; ALS |
| Quantity | Value | Units | Method | Reference | Comment |
| ΔcH°solid | -1704.6 ± 0.45 | kcal/mol | Ccb | Colomina, Jimenez, et al., 1989 | see Boned, Colomina, et al., 1964; Corresponding ΔfHºsolid = -38.81 kcal/mol (simple calculation by NIST; no Washburn corrections); ALS |
| ΔcH°solid | -1700.1 ± 1.3 | kcal/mol | Ccb | Holdiness, 1984 | Hf NR; Corresponding ΔfHºsolid = -43.3 kcal/mol (simple calculation by NIST; no Washburn corrections); ALS |
| ΔcH°solid | -1704.42 ± 0.72 | kcal/mol | Ccb | Parks, West, et al., 1946 | Reanalyzed by Cox and Pilcher, 1970, Original value = -1704.29 ± 0.68 kcal/mol; Corresponding ΔfHºsolid = -39.03 kcal/mol (simple calculation by NIST; no Washburn corrections); ALS |
| Quantity | Value | Units | Method | Reference | Comment |
| S°solid,1 bar | 72.373 | cal/mol*K | N/A | Atake, Gyoten, et al., 1982 | DH |
| S°solid,1 bar | 73.210 | cal/mol*K | N/A | Frankosky and Aston, 1965 | crystaline, I phase; DH |
| S°solid,1 bar | 74.00 | cal/mol*K | N/A | Huffman, Parks, et al., 1930 | crystaline, I phase; Extrapolation below 90 K, 82.38 J/mol*K.; DH |
Constant pressure heat capacity of liquid
| Cp,liquid (cal/mol*K) | Temperature (K) | Reference | Comment |
|---|---|---|---|
| 88.60 | 455. | Kurbatov, 1947 | T = 183 to 256°C, mean Cp, two temperatures.; DH |
Constant pressure heat capacity of solid
| Cp,solid (cal/mol*K) | Temperature (K) | Reference | Comment |
|---|---|---|---|
| 58.17 | 298.15 | Colomina, Jimenez, et al., 1989 | DH |
| 60.256 | 300. | Atake, Gyoten, et al., 1982 | T = 3 to 300 K.; DH |
| 58.709 | 298.15 | Frankosky and Aston, 1965 | crystaline, I phase; T = 13 to 340 K.; DH |
| 61.21 | 293.81 | Momotani, Suga, et al., 1956 | T = 273 to 443 K. Unsmoothed experimental datum.; DH |
| 61.78 | 303. | Spaght, Thomas, et al., 1932 | crystaline, II phase; T = 30 to 200°C.; DH |
| 60.90 | 294.6 | Huffman, Parks, et al., 1930 | crystaline, I phase; T = 85 to 294 K. Value is unsmoothed experimental datum.; DH |
References
Go To: Top, Condensed phase thermochemistry 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]
Notes
Go To: Top, Condensed phase thermochemistry data, References
- Symbols used in this document:
Cp,liquid Constant pressure heat capacity of liquid Cp,solid Constant pressure heat capacity of solid S°solid,1 bar Entropy of solid at standard conditions (1 bar) 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 - Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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