The second conditional estimation method is for liquid heat capacity. If a molecule contains a carbon-carbon double bond (C=C) then the Chueh-Swanson [34], [35] group additivity method is used. The Missenard method includes temperature dependence, so it is used preferentially. If the Chueh-Swanson is used, then the temperature dependence is assumed to be negligible. See Chueh-Swanson [34], [35] for the group contribution tables and groups defined in the method.
The Chueh-Swanson estimation method includes the following special rules for C-C=C and C-C#C groups:
Add 18.8 for carbon groups that satisfy criteria: a carbon group that is joined by a single bond to a carbon group connected by a double or triple bond to a third carbon group.
Exceptions to this 18.8 rule:
-CH3 groups
Carbon groups in a ring.
-CH2- groups (instead add 10.5, unless it satisfies the 18.8 rule twice, then add 10.5 +18.8)