Physical Properties of Phenol Compound: Semi-empirical Calculation of Substituent Effects [Part One]

Problem statement: Physical properties of phenol compound such as steric energy, charge of oxygen, ionization potential, dipole moment, LUMO and bond length have been calculated. Approach: All molecular geometries were minimized by quantum mechanic especially at (AM1) method was used to investigate the effect of a variety of substituents on the phenol (H, o-Cl, p-Cl, m-Cl, o-CH3, m-CH3, p-CH3, o-NH2, m-NH2, o-NO2, m-NO2, p-NO2, 2,4-di-NO2). Global descriptor such as electronic chemical potential (µ), hardness (η), the maximum electronic charge and global electrophilicity index (ω) were determined and used to predict the (pKa) values. Results: The theoretical results (predictive values) found were in good agreement with experimental values. The predictive pKa calculated values by AM1 method gave excellent results with experimental values. The correlation between the predicted values especially global electrophilicity index showed excellent qualitative agreement with the experimental pKa (R2 = 0.95). Conclusion: The present research was to calculate the physical properties of phenol derivatives. Then, the calculated values were compared, quite favorably with experimental values of these properties. In future, we can predict any substituent of set of a phenol compound and compare its value with the experimental.