Additivity of Group Contributions

For compounds of low molar mass, correlations are available. Satoh (1948) proposed a method for the prediction of between Cp at 200, 300 and 400 K by the addition of group contributions. Shaw (1969) used the same method for Cp(298) whereas Johnson and Huang (1955) used it for Cp(293). The question was whether these increments are applicable to polymers. 

Addition of group contributions to be found in Tables 7.1 and 7.2 gives the following result ... 

The framework of interactive design is entirely built on the premise of additivity of group contributions for the estimation of physical properties. Let us look at some typical illustrations. Table XV shows the estimation of normal boiling points T, and normal melting points T , using Joback s group contribution techniques (Joback and Reid, 1987), along with the... 

In Equation 1.3, Z denotes summation. The summation over structural terms only has to be included for certain properties where the assumption of the strict additivity of group contributions results in large errors because the environment of a given group also plays an important role in the contribution of the group to that particular property. For example, structural terms must be used in calculating the Yg of certain types of polymers [3],... 

AHm and ASm were tabulated for polymers, and group contributions were provided for their calculation [30]. It was also indicated that it is very improbable that a method can be derived for the accurate prediction of AHm by a simple addition of group contributions, while ASm... 

While the success of QSAR analyses may be taken as sufficient evidence for the additivity of group contributions to biological activity values, the following question arises are these group contributions more or less constant from one system to the other or do they depend on the choice of the compounds and/or the biological system ... 

Biological Activity Values and the Additivity of Group Contributions... 

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