H Hossaini - Department of Chemistry, Science Faculty, Arak Branch, Islamic Azad University, Arak, Iran
F Shafiei - Department of Chemistry, Science Faculty, Arak Branch, Islamic Azad University, Arak, Iran

One of the most important purpose of applying mathematical and statistical methods isrelationship between structure values with the physical properties, chemical reactivity orbiological activity. As a result the quantitive structure-property relationship ( QSPR)and thequantitive structure-activity(QSAR) studies have been increased in these years.Topological indices as representation of a molecule are important tools in QSPR/QSARstudies for prediction of all kinds of physicochemical properties of compounds [1-3].The physicochemical properties of compounds are important in many fields, including thepharmaceutical, chemistry, biochemistry and environmental sciences. Property estimationscan help to minimize time and cost in produce new chemical materials with desiredproperties.Topological indices (TI)[4-5] are important to use effective mathematical methodsto make good correlations between the data corresponding to several chemical properties.QSPR for predicting the standard absolute entropy (S298 K°) of gaseous organic and inorganiccompounds have been studied [6].Experimental data of benzene derivatives are often scarce,and at this point, topological descriptors provide powerful tools for modeling andextrapolating experimental data.