Isoprene
- Formula: C5H8
- Molecular weight: 68.1170
- IUPAC Standard InChI: InChI=1S/C5H8/c1-4-5(2)3/h4H,1-2H2,3H3
- IUPAC Standard InChIKey: RRHGJUQNOFWUDK-UHFFFAOYSA-N
- CAS Registry Number: 78-79-5
- 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. - Other names: 1,3-Butadiene, 2-methyl-; β-Methylbivinyl; Isopentadiene; 2-Methyl-1,3-butadiene; 2-Methylbutadiene; CH2=C(CH3)CH=CH2; 2-Methylbuta-1,3-diene; 3-Methyl-1,3-butadiene; NSC 9237
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Gas phase thermochemistry data
Go To: Top, Condensed phase thermochemistry data, Reaction thermochemistry data, 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
GT - Glushko Thermocenter, Russian Academy of Sciences, Moscow
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔfH°gas | 75.7 ± 1.0 | kJ/mol | Cm | Fraser and Prosen, 1955 | ALS |
| Quantity | Value | Units | Method | Reference | Comment |
| ΔcH°gas | -3186.6 ± 0.96 | kJ/mol | Cm | Fraser and Prosen, 1955 | Corresponding ΔfHºgas = 75.73 kJ/mol (simple calculation by NIST; no Washburn corrections); ALS |
| Quantity | Value | Units | Method | Reference | Comment |
| S°gas | 314.76 | J/mol*K | N/A | Messerly J.F., 1970 | GT |
Constant pressure heat capacity of gas
| Cp,gas (J/mol*K) | Temperature (K) | Reference | Comment |
|---|---|---|---|
| 36.28 | 50. | Thermodynamics Research Center, 1997 | Values of S(T) and Cp(T) from other statistical mechanics calculation [ Compton D.A.C., 1977] are in close agreement with recommended ones.; GT |
| 47.75 | 100. | ||
| 60.95 | 150. | ||
| 74.81 | 200. | ||
| 95.64 | 273.15 | ||
| 102.69 | 298.15 | ||
| 103.21 | 300. | ||
| 129.59 | 400. | ||
| 152.16 | 500. | ||
| 171.03 | 600. | ||
| 186.95 | 700. | ||
| 200.6 | 800. | ||
| 212.3 | 900. | ||
| 222.5 | 1000. | ||
| 231.3 | 1100. | ||
| 238.9 | 1200. | ||
| 245.5 | 1300. | ||
| 251.2 | 1400. | ||
| 256.2 | 1500. |
Condensed phase thermochemistry data
Go To: Top, Gas phase thermochemistry data, Reaction thermochemistry data, 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 |
|---|---|---|---|---|---|
| ΔcH°liquid | -3158.2 ± 1.6 | kJ/mol | Ccb | Jessup, 1938 | Reanalyzed by Cox and Pilcher, 1970, Original value = -3156.9 ± 1.6 kJ/mol; Corresponding ΔfHºliquid = 47.3 kJ/mol (simple calculation by NIST; no Washburn corrections); ALS |
| Quantity | Value | Units | Method | Reference | Comment |
| S°liquid | 228.28 | J/mol*K | N/A | Messerly, Todd, et al., 1970 | DH |
| S°liquid | 229.2 | J/mol*K | N/A | Warfield and Petree, 1965 | DH |
| S°liquid | 229.3 | J/mol*K | N/A | Bekkedahl and Wood, 1937 | DH |
Constant pressure heat capacity of liquid
| Cp,liquid (J/mol*K) | Temperature (K) | Reference | Comment |
|---|---|---|---|
| 151.08 | 298.15 | Messerly, Todd, et al., 1970 | T = 12 to 320 K.; DH |
| 152.5 | 298.15 | Warfield and Petree, 1965 | T = 20 to 300 K. A reexamination of 37BEK/WOO.; DH |
| 152.6 | 298.2 | Bekkedahl and Wood, 1937 | T = 20 to 300 K.; DH |
Reaction thermochemistry data
Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, 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:
B - John E. Bartmess
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
RCD - Robert C. Dunbar
Note: Please consider using the reaction search for this species. This page allows searching of all reactions involving this species. A general reaction search form is also available. Future versions of this site may rely on reaction search pages in place of the enumerated reaction displays seen below.
Individual Reactions
C5H7- + =
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔrH° | 1613. ± 21. | kJ/mol | G+TS | Bartmess and McIver Jr., 1979 | gas phase; Between H2O, MeOH. Acid: isoprene; B |
| Quantity | Value | Units | Method | Reference | Comment |
| ΔrG° | 1586. ± 21. | kJ/mol | IMRB | Bartmess and McIver Jr., 1979 | gas phase; Between H2O, MeOH. Acid: isoprene; B |
=
+
By formula: C11H8N4 = C6N4 + C5H8
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔrH° | 157. ± 3. | kJ/mol | Cm | Rogers, 1971 | solid phase; Heat of formation derived by 77PED/RYL; ALS |
+
=
By formula: C6N4 + C5H8 = C11H8N4
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔrH° | -157. ± 3. | kJ/mol | Cm | Rogers, 1971 | liquid phase; solvent: Dichloromethane; ALS |
+
= (
•
)
By formula: Ag+ + C5H8 = (Ag+ • C5H8)
| Quantity | Value | Units | Method | Reference | Comment |
|---|---|---|---|---|---|
| ΔrH° | 164. ± 19. | kJ/mol | RAK | Ho, Yang, et al., 1997 | RCD |
References
Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Reaction thermochemistry data, Notes
Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.
Fraser and Prosen, 1955
Fraser, F.M.; Prosen, E.J.,
Heats of combustion and isomerization of six pentadienes and spiropentane,
J. Res. NBS, 1955, 54, 143-148. [all data]
Messerly J.F., 1970
Messerly J.F.,
Chemical thermodynamic properties of the pentadienes. Third law studies,
J. Chem. Eng. Data, 1970, 15, 227-232. [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]
Compton D.A.C., 1977
Compton D.A.C.,
Conformations of conjugated hydrocarbons. Part 2. A spectroscopic and thermodynamic study of cis- and trans-penta-1,3-diene,
J. Chem. Soc. Perkin Trans. 2, 1977, 1311-1315. [all data]
Jessup, 1938
Jessup, R.S.,
Heat of combustion of isoprene,
J. Res. NBS, 1938, 20, 589-597. [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]
Messerly, Todd, et al., 1970
Messerly, J.F.; Todd, S.S.; Guthrie, G.B.,
Chemical thermodynamic properties of the pentadienes,
J. Chem. Eng. Data, 1970, 15, 227-232. [all data]
Warfield and Petree, 1965
Warfield, R.W.; Petree, M.C.,
Thermodynamic properties of natural rubber and isoprene,
Die Makromol. Chemie, 1965, 84, 1-8. [all data]
Bekkedahl and Wood, 1937
Bekkedahl, N.; Wood, L.A.,
Entropy of isoprene from heat-capacity measurements,
J. Res. NBS, 1937, 19, 551-558. [all data]
Bartmess and McIver Jr., 1979
Bartmess, J.E.; McIver Jr.,
The Gas Phase Acidity Scale
in Gas Phase Ion Chemistry, Gas Phase Ion Chemistry, V. 2, M.T. Bowers, Ed., Academic Press, NY, 1979, Ch. 11, Elsevier, 1979. [all data]
Rogers, 1971
Rogers, F.E.,
Thermochemistry of the Diels-Alder reaction. I. Enthalpy of addition of isoprene to tetracyanoethylene,
J. Phys. Chem., 1971, 75, 1734-1737. [all data]
Ho, Yang, et al., 1997
Ho, Y.-P.; Yang, Y.-C.; Klippenstein, S.J.; Dunbar, R.C.,
Binding Energies of Ag+ and Cd+ Complexes from Analysis of Radiative Association Kinetics,
J. Phys. Chem. A, 1997, 101, 18, 3338, https://doi.org/10.1021/jp9637284
. [all data]
Notes
Go To: Top, Gas phase thermochemistry data, Condensed phase thermochemistry data, Reaction thermochemistry data, References
- Symbols used in this document:
Cp,gas Constant pressure heat capacity of gas Cp,liquid Constant pressure heat capacity of liquid S°gas Entropy of gas at standard conditions S°liquid Entropy of liquid at standard conditions ΔcH°gas Enthalpy of combustion of gas at standard conditions ΔcH°liquid Enthalpy of combustion of liquid at standard conditions ΔfH°gas Enthalpy of formation of gas at standard conditions ΔrG° Free energy of reaction at standard conditions ΔrH° Enthalpy of reaction at standard conditions - Data from NIST Standard Reference Database 69: NIST Chemistry WebBook
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