Specific heat of Isoprene

[RonHRob]

Can anyone help me out with the specific heat of Isoprene or Isobutylene?

 

[25362]

From NIST webbook, for liquids

isoprene at 25 Celsius, 152 J/(mol.K) MW: 68.12
isobutylene at -20 Celsius, 121.4 J/(mol.K) MW: 56.11

 

[UmeshMathur]

Further to 25362's values, here are the constants for a temperature dependent equation:
Cp(liq) = A + B*T + C*T^2 + D*T^3, where
Cp(liq) is in [J/(mol K)]
and T is in [K]
REFERENCE: Carl L. Yaws "Chemical Properties Handbook" (McGraw-Hill, 1999). A great general reference, probably the most comprehensive in the open literature. For hydrocarbons, however, I would normally have used the API Technical Data Book except that liquid heat capacities are found using an indirect method.

Yaws' constants for isoprene liquid:
A= 80.542
B= 0.45089
C= -0.0016166
D= 2.7723E-6
Tmin = 128
Tmax = 436
CHECK: Cp(liq) at 25 C = 144.75 [J/(mol K)]


Yaws' constants for isobutylene (or isobutene) liquid:
A= 57.611
B= 0.56251
C= -0.0022985
D= 4.1773E-6
Tmin = 134
Tmax = 376
CHECK: Cp(liq) at 25 C = 131.72 [J/(mol K)]

T(C) T(K) Cp(liq)Isoprene "25362" % Error Cp(liq)Isobutene "25362" % Error
25 298.15 144.746 152 -4.77 131.715
-20 253.15 136.060 120.480 21.4 -0.758

For isoprene, the error between the value from 25362 and that from the above equation is < 5%, acceptable for this property which is not commonly measured and usually estimated from correlations, e.g., Poling, Prausnitz, and O'Connell, "The Properties of Gases and Liquids" (5th Ed., McGraw-Hill, 2001).

 

[UmeshMathur]

Sorry, I had a typographical error on the Cp of liquid isobutene at -20 C; it should be 121.4, not 21.4.