Benzene, 1-ethyl-4-methyl-

Formula: C₉H₁₂
Molecular weight: 120.1916
IUPAC Standard InChI: InChI=1S/C9H12/c1-3-9-6-4-8(2)5-7-9/h4-7H,3H2,1-2H3
IUPAC Standard InChIKey: JRLPEMVDPFPYPJ-UHFFFAOYSA-N
CAS Registry Number: 622-96-8
Chemical structure:
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Other names: Toluene, p-ethyl-; p-Ethylmethylbenzene; p-Ethyltoluene; p-Methylethylbenzene; 1-Ethyl-4-methylbenzene; 1-Methyl-4-ethylbenzene; 4-Ethyltoluene; 4-Methylethylbenzene; para-Ethyltoluene; Benzene, 1-methyl-4-ethyl-; 1,4-Methylethylbenzene; NSC 74177; 4-ethylmethylbenzene
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Gas phase thermochemistry data

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Data compiled by: Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein

Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_gas	-0.78 ± 0.35	kcal/mol	Ccb	Johnson, Prosen, et al., 1945	Hf by Prosen, Johnson, et al., 1946

Condensed phase thermochemistry data

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Data compiled by: Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein

Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_liquid	-11.92 ± 0.34	kcal/mol	Ccb	Johnson, Prosen, et al., 1945	Hf by Prosen, Johnson, et al., 1946
Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_liquid	-1244.45 ± 0.32	kcal/mol	Ccb	Johnson, Prosen, et al., 1945	Hf by Prosen, Johnson, et al., 1946; Corresponding Δ_fHº_liquid = -11.90 kcal/mol (simple calculation by NIST; no Washburn corrections)

Phase change data

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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
DRB - Donald R. Burgess, Jr.

Quantity	Value	Units	Method	Reference	Comment
T_boil	435.1 ± 0.8	K	AVG	N/A	Average of 26 out of 28 values; Individual data points
Quantity	Value	Units	Method	Reference	Comment
T_fus	210. ± 1.	K	AVG	N/A	Average of 12 out of 13 values; Individual data points
Quantity	Value	Units	Method	Reference	Comment
T_c	640.2 ± 1.0	K	N/A	Tsonopoulos and Ambrose, 1995
T_c	640.23	K	N/A	Daubert, Jalowka, et al., 1987	Uncertainty assigned by TRC = 0.2 K; TRC
T_c	640.2	K	N/A	Lyons, 1985	Uncertainty assigned by TRC = 1. K; TRC
Quantity	Value	Units	Method	Reference	Comment
P_c	31.9 ± 0.99	atm	N/A	Tsonopoulos and Ambrose, 1995
P_c	31.91	atm	N/A	Daubert, Jalowka, et al., 1987	Uncertainty assigned by TRC = 0.08 atm; TRC
P_c	31.32	atm	N/A	Lyons, 1985	Uncertainty assigned by TRC = 0.987 atm; TRC
Quantity	Value	Units	Method	Reference	Comment
Δ_vapH°	11.1	kcal/mol	N/A	Ru«7825»icka, Zábranský, et al., 1994	AC
Δ_vapH°	11.1	kcal/mol	N/A	Reid, 1972	AC
Δ_vapH°	11.1	kcal/mol	N/A	Johnson, Prosen, et al., 1945	DRB

Enthalpy of vaporization

Δ_vapH (kcal/mol)	Temperature (K)	Method	Reference	Comment
10.3	364.	A	Stephenson and Malanowski, 1987	Based on data from 349. to 442. K. See also Forziati, Norris, et al., 1949.; AC

Antoine Equation Parameters

log₁₀(P) = A − (B / (T + C))
P = vapor pressure (atm)
T = temperature (K)

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Temperature (K)	A	B	C	Reference
351.46 to 436.16	4.11720	1527.113	-64.229	Forziati, Norris, et al., 1949, 2

In addition to the Thermodynamics Research Center (TRC) data available from this site, much more physical and chemical property data is available from the following TRC products:

References

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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]

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]

Daubert, Jalowka, et al., 1987
Daubert, T.E.; Jalowka, J.W.; Goren, V., Vapor pressure of 22 pure industrial chemicals, AIChE Symp. Ser., 1987, 83, 256, 128-156. [all data]

Lyons, 1985
Lyons, R.L., The determination of critical properties and vapor pressure of thermally stable and unstable compounds, M. S. Thesis, 1985. [all data]

Ru«7825»icka, Zábranský, et al., 1994
Ru«7825»icka, Vlastimil; Zábranský, Milan; Ru«7825»icka, Kvetoslav; Majer, Vladimír, Vapor pressures for a group of high-boiling alkylbenzenes under environmental conditions, Thermochimica Acta, 1994, 245, 121-144, https://doi.org/10.1016/0040-6031(94)85073-9 . [all data]

Reid, 1972
Reid, Robert C., Handbook on vapor pressure and heats of vaporization of hydrocarbons and related compounds, R. C. Wilhort and B. J. Zwolinski, Texas A Research Foundation. College Station, Texas(1971). 329 pages.$10.00, AIChE J., 1972, 18, 6, 1278-1278, https://doi.org/10.1002/aic.690180637 . [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]

Forziati, Norris, et al., 1949
Forziati, Alphonse F.; Norris, William R.; Rossini, Frederick D., Vapor pressures and boiling points of sixty API-NBS hydrocarbons, J. RES. NATL. BUR. STAN., 1949, 43, 6, 555-17, https://doi.org/10.6028/jres.043.050 . [all data]

Forziati, Norris, et al., 1949, 2
Forziati, A.F.; Norris, W.R.; Rossini, F.D., Vapor Pressures and Boiling Points of Sixty API-NBS Hydrocarbons, J. Res. Natl. Bur. Stand. (U.S.), 1949, 43, 6, 555-563, https://doi.org/10.6028/jres.043.050 . [all data]

Notes

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Symbols used in this document:

P_c	Critical pressure
T_boil	Boiling point
T_c	Critical temperature
T_fus	Fusion (melting) point
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
Δ_vapH	Enthalpy of vaporization
Δ_vapH°	Enthalpy of vaporization at standard conditions

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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