QSPR study of standard absolute entropies for gaseous organic compounds using novel molecular connectivity indexes and Ring parameter

For predicting the standard absolute entropies of gaseous organic compounds, variable molecular connectivity index image and Ring parameter H, based on adjacency matrix of molecular graphs, variable atomic valence connectivity index image, and the numbers of chains (cycles) atomic of molecule niR, were proposed. The optimal values of parameters c, a, mi, and y included in the definition of image, and image can be found by optimization method. When c = 0.91, a = 1.3, and y = 0.22, a good four-parameter model can be constructed from H and image by using the best subsets regression analysis method for the standard absolute entropies of gaseous organic compounds. The results show that the MLR method can provide an accurate model for the prediction of the standard absolute entropies of gaseous organic compounds.