Ethylbenzene

Formula: C₈H₁₀
Molecular weight: 106.1650
IUPAC Standard InChI: InChI=1S/C8H10/c1-2-8-6-4-3-5-7-8/h3-7H,2H2,1H3
IUPAC Standard InChIKey: YNQLUTRBYVCPMQ-UHFFFAOYSA-N
CAS Registry Number: 100-41-4
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:
- Ethylbenzene-d10
Other names: Benzene, ethyl-; Ethylbenzol; EB; Phenylethane; Aethylbenzol; Ethylbenzeen; Etilbenzene; Etylobenzen; NCI-C56393; UN 1175; α-Methyltoluene; NSC 406903
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Gas phase thermochemistry data

Go To: Top, Gas phase ion energetics data, IR Spectrum, References, Notes

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

Quantity	Value	Units	Method	Reference	Comment
Δ_fH°_gas	7.12 ± 0.20	kcal/mol	Ccb	Prosen, Gilmont, et al., 1945	Hf by Prosen, Johnson, et al., 1946; ALS
Δ_fH°_gas	11.7 ± 0.96	kcal/mol	Ccb	N/A	Value computed using Δ_fH_liquid° from missing citation and Δ_vapH° value of 10.1 kcal/mol from missing citation. recalculated with modern CO2,H2O thermo; estimated uncertainty (NOTE all values in source also have wrong sign); DRB
Δ_fH°_gas	16.6	kcal/mol	N/A	Moureu and Andre, 1914	Value computed using Δ_fH_liquid° value of 27.0 kj/mol from Moureu and Andre, 1914 and Δ_vapH° value of 42.3 kj/mol from Prosen, Gilmont, et al., 1945.; DRB
Quantity	Value	Units	Method	Reference	Comment
S°_gas	86.2 ± 0.1	cal/mol*K	N/A	Miller A., 1978	S(298.16 K)=361.5 J/mol*K was obtained from earlier experimental data [ Guttman L., 1943].; GT

Constant pressure heat capacity of gas

C_p,gas (cal/mol*K)	Temperature (K)	Reference	Comment
10.60	50.	Thermodynamics Research Center, 1997	Recommended values are in good agreement with other statistically calculated data [ Miller A., 1978, Taylor W.J., 1946].; GT
13.80	100.
17.29	150.
21.16	200.
27.935	273.15
30.449	298.15
30.638	300.
40.619	400.
49.374	500.
56.585	600.
62.502	700.
67.419	800.
71.551	900.
75.057	1000.
78.050	1100.
80.609	1200.
82.811	1300.
84.706	1400.
86.346	1500.

Constant pressure heat capacity of gas

C_p,gas (cal/mol*K)	Temperature (K)	Reference	Comment
38.06 ± 0.19	373.15	Hossenlopp I.A., 1981	Heat capacities determined from acoustical measurements [ Colgate S.O., 1990] (124.98, 138.21, 158.84, and 173.88 J/mol*K at 298.15, 323.15, 373.15, and 408.15 K, respectively) are slightly lower than calorimetric ones. Please also see Scott R.B., 1945.; GT
39.257 ± 0.079	385.65
40.452 ± 0.081	398.15
42.772 ± 0.086	423.15
45.000 ± 0.091	448.15
47.168 ± 0.093	473.15
49.221 ± 0.098	498.15
51.15 ± 0.10	523.15

Gas phase ion energetics data

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

Data evaluated as indicated in comments:
HL - Edward P. Hunter and Sharon G. Lias
L - Sharon G. Lias

Data compiled as indicated in comments:
B - John E. Bartmess
MM - Michael M. Meot-Ner (Mautner)
LBLHLM - Sharon G. Lias, John E. Bartmess, Joel F. Liebman, John L. Holmes, Rhoda D. Levin, and W. Gary Mallard
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
RDSH - Henry M. Rosenstock, Keith Draxl, Bruce W. Steiner, and John T. Herron

View reactions leading to C₈H₁₀⁺ (ion structure unspecified)

Quantity	Value	Units	Method	Reference	Comment
IE (evaluated)	8.77 ± 0.01	eV	N/A	N/A	L
Quantity	Value	Units	Method	Reference	Comment
Proton affinity (review)	188.3	kcal/mol	N/A	Hunter and Lias, 1998	HL
Quantity	Value	Units	Method	Reference	Comment
Gas basicity	181.7	kcal/mol	N/A	Hunter and Lias, 1998	HL

Proton affinity at 298K

Proton affinity (kcal/mol)	Reference	Comment
188.8	Aue, Guidoni, et al., 2000	Experimental literature data re-evaluated by the authors using ab initio protonation entropies; MM

Gas basicity at 298K

Gas basicity (review) (kcal/mol)	Reference	Comment
181.7	Aue, Guidoni, et al., 2000	Experimental literature data re-evaluated by the authors using ab initio protonation entropies; MM

Ionization energy determinations

IE (eV)	Method	Reference	Comment
8.77	PE	Howell, Goncalves, et al., 1984	LBLHLM
8.61	PE	Klasinc, Kovac, et al., 1983	LBLHLM
8.65 ± 0.10	EI	Selim and Helal, 1982	LBLHLM
8.76	EI	McLoughlin, Morrison, et al., 1979	LLK
8.768 ± 0.008	EQ	Lias and Ausloos, 1978	LLK
8.75 ± 0.05	PI	Akopyan and Vilesov, 1966	RDSH
8.76 ± 0.01	PI	Watanabe, Nakayama, et al., 1962	RDSH
8.77 ± 0.01	S	Hammond, Price, et al., 1950	RDSH
8.77	PE	Howell, Goncalves, et al., 1984	Vertical value; LBLHLM
8.73	PE	Klasinc, Kovac, et al., 1983	Vertical value; LBLHLM
9.38	PE	Deshmukh, Dutta, et al., 1982	Vertical value; LBLHLM

Appearance energy determinations

Ion	AE (eV)	Other Products	Method	Reference	Comment
C₅H₅⁺	16.2 ± 0.2	C₂H₂+CH₃	EI	Tajima and Tsuchiya, 1973	LLK
C₆H₆⁺	11.0 ± 0.1	C₂H₄?	PI	Akopyan and Vilesov, 1966	RDSH
C₇H₇⁺	9.9 ± 0.1	CH₃	TRPI	Lifshitz and Malinovich, 1984	LBLHLM
C₇H₇⁺	10.15 ± 0.10	CH₃	EI	Selim and Helal, 1982	LBLHLM
C₇H₇⁺	10.06	CH₃	EI	McLoughlin, Morrison, et al., 1979	LLK
C₇H₇⁺	10.9 ± 0.1	CH₃	PI	Akopyan and Vilesov, 1966	RDSH
C₈H₉⁺	10.60	H	EI	McLoughlin, Morrison, et al., 1979	LLK
C₈H₉⁺	12.1 ± 0.1	H	PI	Akopyan and Vilesov, 1966	RDSH
C₈H₉⁺	11.4 ± 0.1	H	EI	Meyer, Haynes, et al., 1965	RDSH

De-protonation reactions

C₈H₉^- + = Ethylbenzene

By formula: C₈H₉^- + H⁺ = C₈H₁₀

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	406.0 ± 4.6	kcal/mol	CIDT	Graul and Squires, 1990	gas phase; From decarboxylation threshold. Stable form probably the spiro[2.5]octadienide Maas and van Keelen, 1989; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	397.7 ± 4.7	kcal/mol	H-TS	Graul and Squires, 1990	gas phase; From decarboxylation threshold. Stable form probably the spiro[2.5]octadienide Maas and van Keelen, 1989; B

C₈H₉^- + = Ethylbenzene

By formula: C₈H₉^- + H⁺ = C₈H₁₀

Quantity	Value	Units	Method	Reference	Comment
Δ_rH°	379.7 ± 2.1	kcal/mol	G+TS	Bartmess, Scott, et al., 1979	gas phase; value altered from reference due to change in acidity scale; B
Quantity	Value	Units	Method	Reference	Comment
Δ_rG°	373.3 ± 2.0	kcal/mol	IMRE	Bartmess, Scott, et al., 1979	gas phase; value altered from reference due to change in acidity scale; B

IR Spectrum

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

Data compiled by: Coblentz Society, Inc.

Data compiled by: NIST Mass Spectrometry Data Center, William E. Wallace, director

gas; HP-GC/MS/IRD

Data compiled by: Pamela M. Chu, Franklin R. Guenther, George C. Rhoderick, and Walter J. Lafferty

gas; IFS66V (Bruker); 3-Term B-H Apodization
0.1250, 0.2410, 0.4820, 0.9640, 1.9290 cm^-1 resolution
gas; IFS66V (Bruker); Boxcar Apodization
0.1250, 0.2410, 0.4820, 0.9640, 1.9290 cm^-1 resolution
gas; IFS66V (Bruker); Happ Genzel Apodization
0.1250, 0.2410, 0.4820, 0.9640, 1.9290 cm^-1 resolution
gas; IFS66V (Bruker); NB Strong Apodization
0.1250, 0.2410, 0.4820, 0.9640, 1.9290 cm^-1 resolution
gas; IFS66V (Bruker); Triangular Apodization
0.1250, 0.2410, 0.4820, 0.9640, 1.9290 cm^-1 resolution

References

Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, IR Spectrum, Notes

Prosen, Gilmont, et al., 1945
Prosen, E.J.; Gilmont, R.; Rossini, F.D., Heats of combustion of benzene, toluene, ethyl-benzene, o-xylene, m-xylene, p-xylene, n-propylbenzene, and styrene, J. Res. NBS, 1945, 34, 65-70. [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]

Moureu and Andre, 1914
Moureu, C.; Andre, E., Thermochimie des composes acetyleniques, Ann. Chim. Phys., 1914, 1, 113-145. [all data]

Miller A., 1978
Miller A., Chemical thermodynamic properties of ethylbenzene, J. Chem. Phys., 1978, 68, 1317-1319. [all data]

Guttman L., 1943
Guttman L., Jr., The thermodynamics of styrene (phenylethylene), including equilibrium of formation from ethylbenzene, J. Am. Chem. Soc., 1943, 65, 1246-1247. [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 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]

Hossenlopp I.A., 1981
Hossenlopp I.A., Vapor heat capacities and enthalpies of vaporization of four aromatic and/or cycloalkane hydrocarbons, J. Chem. Thermodyn., 1981, 13, 423-428. [all data]

Colgate S.O., 1990
Colgate S.O., Acoustical determination of ideal gas heat capacities of three C-8 compounds, Fluid Phase Equilib., 1990, 60, 191-203. [all data]

Scott R.B., 1945
Scott R.B., Specific heats of gaseous 1,3-butadiene, isobutene, styrene, and ethylbenzene, J. Res. Nat. Bur. Stand., 1945, 34, 243-254. [all data]

Hunter and Lias, 1998
Hunter, E.P.; Lias, S.G., Evaluated Gas Phase Basicities and Proton Affinities of Molecules: An Update, J. Phys. Chem. Ref. Data, 1998, 27, 3, 413-656, https://doi.org/10.1063/1.556018 . [all data]

Aue, Guidoni, et al., 2000
Aue, D.H.; Guidoni, M.; Betowski, L.D., Ab initio calculated gas-phase basicities of polynuclear aromatic hydrocarbons, Int. J. Mass Spectrom., 2000, 201, 283. [all data]

Howell, Goncalves, et al., 1984
Howell, J.O.; Goncalves, J.M.; Amatore, C.; Klasinc, L.; Wightman, R.M.; Kochi, J.K., Electron transfer from aromatic hydrocarbons and their π-complexes with metals. Comparison of the standard oxidation potentials and vertical ionization potentials, J. Am. Chem. Soc., 1984, 106, 3968. [all data]

Klasinc, Kovac, et al., 1983
Klasinc, L.; Kovac, B.; Gusten, H., Photoelectron spectra of acenes. Electronic structure and substituent effects, Pure Appl. Chem., 1983, 55, 289. [all data]

Selim and Helal, 1982
Selim, E.T.M.; Helal, A.I., The study of C₁-C₃ monosubstituted alkyl benzenes by the inverse convolution of first differential ionization efficiency curves, Org. Mass Spectrom., 1982, 17, 539. [all data]

McLoughlin, Morrison, et al., 1979
McLoughlin, R.G.; Morrison, J.D.; Traeger, J.C., Photoionization of the C-1 - C-4 monosubstituted alkyl benzenes: Thermochemistry of [C₇H₇]⁺ and [C₈H₉]⁺ formation, Org. Mass Spectrom., 1979, 14, 104. [all data]

Lias and Ausloos, 1978
Lias, S.G.; Ausloos, P.J., eIonization energies of organic compounds by equilibrium measurements, J. Am. Chem. Soc., 1978, 100, 6027. [all data]

Akopyan and Vilesov, 1966
Akopyan, M.E.; Vilesov, F.I., A mass-spectrometric study of the photo-ionisation of benzene derivatives at wavelengths up to 885 A, Zh. Fiz. Khim., 1966, 40, 125, In original 63. [all data]

Watanabe, Nakayama, et al., 1962
Watanabe, K.; Nakayama, T.; Mottl, J., Ionization potentials of some molecules, J. Quant. Spectry. Radiative Transfer, 1962, 2, 369. [all data]

Hammond, Price, et al., 1950
Hammond, V.J.; Price, W.C.; Teegan, J.P.; Walsh, A.D., The absorption spectra of some substituted benzenes and naphthalenes in the vacuum ultra-violet, Faraday Discuss. Chem. Soc., 1950, 9, 53. [all data]

Deshmukh, Dutta, et al., 1982
Deshmukh, P.; Dutta, T.K.; Hwang, J.L.-S.; Housecroft, C.E.; Fehlner, T.P., Photoelectron spectroscopic measurements of the relative charge on carbyne fragments bound to polynuclear cobalt carbonyl clusters, J. Am. Chem. Soc., 1982, 104, 1740. [all data]

Tajima and Tsuchiya, 1973
Tajima, S.; Tsuchiya, T., Energetics consideration of C₅H₅⁺ ions produced from various precursors by electron impact, Bull. Chem. Soc. Jpn., 1973, 46, 3291. [all data]

Lifshitz and Malinovich, 1984
Lifshitz, C.; Malinovich, Y., Time resolved photoionization mass spectrometry in the millisecond range, Int. J. Mass Spectrom. Ion Processes, 1984, 60, 99. [all data]

Meyer, Haynes, et al., 1965
Meyer, F.; Haynes, P.; McLean, S.; Harrison, A.G., An electron impact study of some C₈H₁₀ isomers, Can. J. Chem., 1965, 43, 211. [all data]

Graul and Squires, 1990
Graul, S.T.; Squires, R.R., Gas-Phase Acidities Derived from Threshold Energies for Activated Reactions, J. Am. Chem. Soc., 1990, 112, 7, 2517, https://doi.org/10.1021/ja00163a007 . [all data]

Maas and van Keelen, 1989
Maas, W.P.M.; van Keelen, P.A., On the Generation and Characterization of the Spiro[2,5]Octadienyl Anion in the Gas Phase, Org. Mass Spectrom., 1989, 24, 8, 546, https://doi.org/10.1002/oms.1210240807 . [all data]

Bartmess, Scott, et al., 1979
Bartmess, J.E.; Scott, J.A.; McIver, R.T., Jr., The gas phase acidity scale from methanol to phenol, J. Am. Chem. Soc., 1979, 101, 6047. [all data]

Notes

Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, IR Spectrum, References

Symbols used in this document:

AE	Appearance energy
C_p,gas	Constant pressure heat capacity of gas
IE (evaluated)	Recommended ionization energy
S°_gas	Entropy of gas at standard conditions
Δ_fH°_gas	Enthalpy of formation of gas at standard conditions
Δ_rG°	Free energy of reaction at standard conditions
Δ_rH°	Enthalpy of reaction at standard conditions

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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