Benzene, 1,2,3-trimethyl-

Formula: C₉H₁₂
Molecular weight: 120.1916
IUPAC Standard InChI: InChI=1S/C9H12/c1-7-5-4-6-8(2)9(7)3/h4-6H,1-3H3
IUPAC Standard InChIKey: FYGHSUNMUKGBRK-UHFFFAOYSA-N
CAS Registry Number: 526-73-8
Chemical structure:
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Other names: Hemimellitene; 1,2,3-Trimethylbenzene; Hemellitol; 1,2,3-TrimethyIbenzene; 1,2,3-trimethylbenzene (hemimellitene)
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Gas phase thermochemistry data

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Data compiled as indicated in comments:
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
GT - Glushko Thermocenter, Russian Academy of Sciences, Moscow

Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_gas	-9.6 ± 1.3	kJ/mol	Ccb	Johnson, Prosen, et al., 1945	Hf by Prosen, Johnson, et al., 1946; ALS
Quantity	Value	Units	Method	Reference	Comment
S°_gas	384.84 ± 0.63	J/mol*K	N/A	Taylor R.D., 1955	GT

Constant pressure heat capacity of gas

C_p,gas (J/mol*K)	Temperature (K)	Reference	Comment
117.9	200.	Draeger, 1985	Discrepancies with other statistically calculated values [ Taylor W.J., 1946, Hastings S.H., 1957, Thermodynamics Research Center, 1997] amount up to 5 J/mol*K in S(T) and Cp(T).; GT
148.3	273.15
159.1 ± 0.4	298.15
159.9	300.
202.6	400.
241.5	500.
274.7	600.
302.8	700.
326.7	800.
347.0	900.
364.3	1000.
379.2	1100.
392.0	1200.
402.9	1300.
412.4	1400.
420.6	1500.

Condensed phase thermochemistry data

Go To: Top, Gas phase thermochemistry data, References, Notes

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
Δ_fH°_liquid	-58.6 ± 1.3	kJ/mol	Ccb	Johnson, Prosen, et al., 1945	Hf by Prosen, Johnson, et al., 1946; ALS
Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_liquid	-5198.0 ± 1.2	kJ/mol	Ccb	Johnson, Prosen, et al., 1945	Hf by Prosen, Johnson, et al., 1946; Corresponding Δ_fHº_liquid = -58.53 kJ/mol (simple calculation by NIST; no Washburn corrections); ALS
Quantity	Value	Units	Method	Reference	Comment
S°_liquid	267.94	J/mol*K	N/A	Taylor, Johnson, et al., 1955	DH

Constant pressure heat capacity of liquid

C_p,liquid (J/mol*K)	Temperature (K)	Reference	Comment
216.44	298.15	Taylor, Johnson, et al., 1955	T = 19 to 301 K.; DH

References

Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Notes

Johnson, Prosen, et al., 1945
Johnson, W.H.; Prosen, E.J.; Rossini, F.D., Heats of combustion and isomerization of the eight C₉H₁₂ alkylbenzenes, J. Res. NBS, 1945, 35, 141-146. [all data]

Prosen, Johnson, et al., 1946
Prosen, E.J.; Johnson, W.H.; Rossini, F.D., Heats of combustion and formation at 25°C of the alkylbenzenes through C₁₀H₁₄, and of the higher normal monoalkylbenzenes, J. Res. NBS, 1946, 36, 455-461. [all data]

Taylor R.D., 1955
Taylor R.D., Entropy, heat capacity, and heats of transition of 1,2,3-trimethylbenzene, J. Chem. Phys., 1955, 23, 1225-1231. [all data]

Draeger, 1985
Draeger, J.A., The methylbenzenes II. Fundamental vibrational shifts, statistical thermodynamic functions, and properties of formation, J. Chem. Thermodyn., 1985, 17, 263-275. [all data]

Taylor W.J., 1946
Taylor W.J., Heats, equilibrium constants, and free energies of formation of the alkylbenzenes, J. Res. Nat. Bur. Stand., 1946, 37, 95-122. [all data]

Hastings S.H., 1957
Hastings S.H., Thermodynamic properties of selected methylbenzenes from 0 to 1000 K, J. Phys. Chem., 1957, 61, 730-735. [all data]

Thermodynamics Research Center, 1997
Thermodynamics Research Center, Selected Values of Properties of Chemical Compounds., Thermodynamics Research Center, Texas A&M University, College Station, Texas, 1997. [all data]

Taylor, Johnson, et al., 1955
Taylor, R.D.; Johnson, B.H.; Kilpatrick, J.E., Entropy, heat capacity, and heats of transition of 1,2,3-trimethylbenzene, J. Chem. Phys., 1955, 23, 1225-1231. [all data]

Notes

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Symbols used in this document:

C_p,gas	Constant pressure heat capacity of gas
C_p,liquid	Constant pressure heat capacity of liquid
S°_gas	Entropy of gas at standard conditions
S°_liquid	Entropy of liquid at standard conditions
Δ_cH°_liquid	Enthalpy of combustion of liquid at standard conditions
Δ_fH°_gas	Enthalpy of formation of gas at standard conditions
Δ_fH°_liquid	Enthalpy of formation of liquid at standard conditions

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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