Abstract
Positional effect of NH2 group on the properties of aminobenzenesulphonic acid (AMBSA) has been investigated. Potential energy scan (PES) calculation revealed the energy difference between the two global minima predicted for each of the derivatives to be decreasing with the increasing distance between the -NH2 substituent and the -SO3H moiety. On the other hand, the zero-point energy affirmed the ortho and para substituted AMBSAs as being more stable than the meta counterpart by 1.7 kcal/mol. The derivatives showed comparable chemical reactivity, whereas the simulation of their solubility in the selected solvents affirmed the 4-aminobenzenesulphonic acid to be generally more soluble than the other derivatives. Application of Kamlet-Taft model on the absorption data of the aminobenzenesulphonic acids revealed the influence of solvent polarity together with hydrogen bonding ability on their solubility. On the part of vibrational property, the vibrational modes associated with -SO3H moiety were found to be sensitive to the position of amino substituent.