Homologous series, thermochemical properties

It has been firmly established that thermochemical properties of a homologous series of compounds show a linear dependence on the number of carbon atoms in the alkyl group1,9 11. Especially useful is equation 1 which expresses the standard molar enthalpies of formation of a homologous series as a function of the total number of carbon atoms in the compound, nc. 

The existence and stability of homologous series of compounds lie at the foundations of organic chemistry. The systematic variation of properties within the saturated and unsaturated series, both linear and cyclic, provides a firm basis for the development and criticism of stereochemical and thermochemical concepts, and for theories of chemical reactivity. 

Transition state properties cannot be directly estimated from this method. To do this, as mentioned in Chapter 3, Br0nsted—Evans—Polanyi relationships are appHed relating kinetics with thermochemical properties. Such relationships use correlations developed from similar reactions belonging to the same homologous series. 

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