Executive Summary : | Surfactants molecules behave as simple electrolytes at low concentrations. After achieving certain minimum concentrations, the molecules start to form different types of microstructures (micelles, vesicles, bilayers, etc.). The effects of surfactants and their self-assembled forms on chemical reactions is an interesting field of research for chemists and biologists. The micro-heterogeneous systems formed by amphiphilic molecules can induce regio-selectivity if one of the reactants is a compound with one polar and one nonpolar end wherein the reactants may align at the interface in an amphiphilic manner causing water-soluble species to be preferentially attacked by the polar end and an oil-soluble species by the apolar end. Gemini surfactants are known as new generation surfactants. They are made up of two hydrophobic chains and two polar head-groups covalently linked through a spacer and have several unique aggregation properties in comparison with their conventional counterparts, such as much lower critical micelle concentration (cmc), strong dependence on spacer structure, high surface and wetting activity, special aggregate morphology, and so on. The rate of the reaction can be accelerated or decelerated depending on the chemical system, the type of the surfactant and other factors such as pH, ionic strength, etc. Hence, several ways can be articulated to manipulate the system using organized assemblies of conventional and gemini surfactants for carrying out complex organic transformations. Further, associated colloids can influence the equilibria and concentration or depletion of reactants in the interfacial region. Unfortunately, the domain has not been well explored. Why can’t we use the microstructures formed by various conventional and gemini surfactants to carry out commercially important organic reactions so that the need for organic solvents can be minimized along with increasing the yield and efficiency of the reaction? This proposal aims to investigate the effects of different microstructures resulting from conventional as well as gemini surfactants through the synthesis of 2-Quinolones and 1,6-Naphthyridines. Following are the specific objectives of the proposal: (i) Effects of addition of tetradecyltrimethylammonium bromide (TTAB) and cetyltrimethylammonium bromide (CTAB). (ii) Effects of addition of alkanediyl-α,ω-bis(alkyldimethylammonium bromide) (m-s-m; m = 14, 16, s = 4, 5, 6) gemini surfactants. (iii) Effects of concurrent addition of conventional and gemini surfactants (role of mixed microstructures). (iv) Effects of temperature and pH on selected systems. It is expected that, after the study, we shall be able to correlate and optimize the activity/capability of these amphiphiles for various organic transformations based on the structure, concentration and other solution conditions. Further, the effect of specific microstructure formed by both conventional and gemini surfactants on the reactions can also be explored. |