1,3-Cyclopentadiene

Formula: C₅H₆
Molecular weight: 66.1011
IUPAC Standard InChI: InChI=1S/C5H6/c1-2-4-5-3-1/h1-4H,5H2
IUPAC Standard InChIKey: ZSWFCLXCOIISFI-UHFFFAOYSA-N
CAS Registry Number: 542-92-7
Chemical structure:
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Other names: Cyclopentadiene; Pentole; Pyropentylene; R-Pentine
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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	33.2	kcal/mol	Chyd	Roth, Adamczak, et al., 1991	ALS
Δ_fH°_gas	31.89	kcal/mol	Eqk	Furuyama, Golden, et al., 1970	ALS
Quantity	Value	Units	Method	Reference	Comment
Δ_cH°_gas	-707. ± 7.	kcal/mol	Ccb	Wassermann, 1935	Corresponding Δ_fHº_gas = 32. kcal/mol (simple calculation by NIST; no Washburn corrections); ALS
Quantity	Value	Units	Method	Reference	Comment
S°_gas	65.600	cal/mol*K	N/A	Furuyama S., 1970	This a second law entropy value was obtained from study of gas-phase equilibrium. The value of S(298.2 K)=270.3(4.2) J/mol*K was obtained from other equilibrium study [ Grant C.J., 1969].; GT

Constant pressure heat capacity of gas

C_p,gas (cal/mol*K)	Temperature (K)	Reference	Comment
7.957	50.	Dorofeeva O.V., 1986	Recommended S(T) values differ from other statistically calculated values [ Turnbull A.G., 1967, Furuyama S., 1970] up to 2.6 J/molK. Discrepancies in Cp(T) values amount to 1.3-4.3 J/molK. There is an excellent agreement between selected values of S(T) and Cp(T) and those obtained by ab initio calculation [ Karni M., 1991].; GT
8.375	100.
9.637	150.
11.84	200.
16.32	273.15
18.01 ± 0.48	298.15
18.14	300.
24.689	400.
30.222	500.
34.663	600.
38.250	700.
41.207	800.
43.683	900.
45.782	1000.
47.572	1100.
49.109	1200.
50.430	1300.
51.570	1400.
52.562	1500.

References

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Roth, Adamczak, et al., 1991
Roth, W.R.; Adamczak, O.; Breuckmann, R.; Lennartz, H.-W.; Boese, R., Die Berechnung von Resonanzenergien; das MM2ERW-Kraftfeld, Chem. Ber., 1991, 124, 2499-2521. [all data]

Furuyama, Golden, et al., 1970
Furuyama, S.; Golden, D.M.; Benson, S.W., Thermochemistry of cyclopentene and cyclopentadiene from studies of gas-phase equilibria, J. Chem. Thermodyn., 1970, 2, 161-169. [all data]

Wassermann, 1935
Wassermann, A., The mechanism of additions to double bonds. Part I. Thermochemistry and kinetics of a diene synthesis, J. Chem. Soc., 1935, 828-838. [all data]

Furuyama S., 1970
Furuyama S., Thermochemistry of cyclopentene and cyclopentadiene from studies of gas-phase equilibria, J. Chem. Thermodyn., 1970, 2, 161-169. [all data]

Grant C.J., 1969
Grant C.J., Reversibility in the gas-phase decomposition of cyclopentene. The entropy of cyclopentadiene, J. Chem. Soc. Chem. Comm., 1969, 667-668. [all data]

Dorofeeva O.V., 1986
Dorofeeva O.V., Thermodynamic properties of twenty-one monocyclic hydrocarbons, J. Phys. Chem. Ref. Data, 1986, 15, 437-464. [all data]

Turnbull A.G., 1967
Turnbull A.G., Thermochemistry of biscyclopentadienyl metal compounds, Austral. J. Chem., 1967, 20, 2059-2067. [all data]

Karni M., 1991
Karni M., Ab initio calculations and ideal gas thermodynamic functions of cyclopentadiene and cyclopentadiene derivatives, J. Phys. Chem. Ref. Data, 1991, 20, 665-683. [all data]

Notes

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Symbols used in this document:

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

Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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