Abstract
For the first time a quantum-chemical method PM3 (Parametric Method 3) in semi empirical approach appreciated geometric and electronic parameters of the new acylated form the molecules 6-APA (6-aminopenicillanic acid), identified patterns of change according to the nature of the acylating agent. In general, the process of acylation of the molecule 6-APA by acylating agents (phosgene and acetyl chloride) leads to much larger changes in new systems of electronic structure than in its spatial structure. In this electronic structure analysis indicates that the acylation of 6-APA of the molecule both acylating agents leads to formation of more stable in the plan hydrolytic cleavage of form of this acid. This fact is a prediction of the characters and is positive for future synthesis of new antibiotics on the basis of 6-APA. Significant absolute value and the sign of the negative enthalpy of formation calculated by PM3, for both systems 6-APA-phosgene 6-APA-acetyl chloride indicate their high thermodynamic stability. The most stable in terms of the thermodynamic system is the 6-APA-acetyl chloride.