A Systematic Property Based Approach for Molecular Synthesis Using Higher Order Molecular Groups and Molecular Descriptors

Abstract

In this work, algorithms have been developed for the design of molecules corresponding to the optimum performance of a process. The concept of property clustering has been extended into molecular design based on second and third order group contribution methods. An algebraic approach has been developed utilizing higher order molecular groups built from first order groups. The significant aspect of the aforementioned method is that both the application range and reliability of the molecular property clustering technique are considerably increased by incorporating second and third order estimation. A methodology has been developed for incorporating the property contribution predicted using combined group contribution and connectivity indices into the design framework in case the property contributions of any of the molecular groups of interest are not available in literature. For the design of simple mono-functional molecules, a modified visual approach has been used whereas for the design of more complicated structures and/or for treating more than three properties at a time, an algebraic method has been developed. Until now, most reverse property prediction algorithms are based on group contribution methods. However, a variety of properties can be predicted using Quantitative Structure Activity/Property Relationships (QSAR/QSPR) models. QSAR models make use of topological indices to predict physical properties and biological activities. In this dissertation, a new algorithm has been developed to include topological index based property models into the reverse problem formulation framework. This algorithm makes use of the concept of molecular signature descriptors to incorporate a variety of different topological indices on a common platform. A large number of environmental, safety and health related constraints can be now investigated as a part of the integrated process and molecular design. An algorithm for the enumeration of the molecular structures has been developed with very low degeneracy. In the last part, a general framework has been proposed to simultaneously integrate process and product design problems with flowsheet design. This methodology will identify the best candidate molecules that provide the optimum process performance with minimum energy utilization. The dissertation concludes with a list of potential areas where more study can be conducted based on the developed algorithms.