Constantinou-Gani group contribution method

Here H 8 and F2 8 can be estimated using the Constantinou-Gani group contribution method (Constantinou and Gani, 1994). 

Constantinou, L., R. Gani, and J. P. O Connell, "Estimation of the acentric factor and the liquid molar volume at 298K through a new group contribution method". Fluid Phase Equilibria 103, 11, (1995). 

Constantinou, L., Gani, R., (1994). New Group-contribution method for estimating properties of pure compounds. AIChE J., 40(10), 1697-1710. 

Constantinou, L., and R. Gani, New Group Contribution Method for Estimating Properties of Pure Compounds. AIChE J., 1994 40, 1697-1710. 

Critical temperatures, critical pressures, and critical volumes can be estimated with group contribution methods. The most common ones are from Lydersen (1), Ambrose [2, 3), joback and Reid [4], and Constantinou and Gani (5). They are all explained in [6]. A recent development by Rarey and Nannoolal [7, 8) seems to be the most accurate one, but it is more difficult to apply. 

Although estimation methods for the acentric factor are available (e.g., group contribution method of Constantinou and Gani [11]), this concept is not recommended, as an estimation of co would only be a redundancy of the normal boiling point estimation. To avoid inconsistencies, it is recommended that co is always calculated by its defining equation 2.157. If the vapor pressure curve is unknown, the normal boiling point and the critical point can be estimated, and the Hoffmann-Florin equation or the Rarey/Moller method (Section 3.2.1) can be used to calculate the vapor pressure curve. 

The normal boiling point is an easily accessible physical property and has been measured for a large number of substances. In case that it is not available, the normal boiling point can be estimated with group contribution methods, for example, Joback and Reid [4] and Constantinou and Gani [5], analogously to the estimation of the critical point. The estimation formula for the Joback method is... 

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