Study on quantitative structure-property relationship of alkyl benzenes by the principal quantum number topological index

The characteristic value t(i) = m(i)( n(i) - 1) + h(i) of an atom is defined by pnincipal quantum number. The topological index of principal quantum number (n)Q is formed by t(i): (n)Q = Sigma(t(i)(.)t(j)(.)t(k)(...))(0.5), in which (0)Q and (1)Q are defined as (0)Q = Sigma(t(i))(0.5), (1)Q = Sigma(t(i)(.)t(j))(0.5). A general and empirical formula that is the correlation between physical and chemical properties with (0)Q, (1)Q of alkyl benzenes is proposed as follows: p = a + b (0)Q + c (1)Q, where p stands for physical and chemical properties of alkyl benzene. (0)Q and (1)Q have good correlation with physical and chemical properties of alkyl benzenes such as combustion heat, parachor, boiling point, heat of vaporization, standard free energy of formation, standard entropy, molar volume, water solubility, partition coefficient of n-octanol/water. The results show that all the correlation coefficients are larger than 0.99.