The Influence of Monomers upon Microemulsions with Short Chain Cosurfactant

Several monomers (i.e., acrylonitrile (ACN), ethyl acrylate (EtA), acrylate of 2 ethylhexyl (EHA), butyl acrylate (BuA), vinyl acetate (VAc), methyl methacrylate (MMA) and styrene (St)) were investigated in order to study their capacities to form microemulsions. The surfactant was nonyl phenol ethoxylate with 25 moles ethylene oxide and ethanol was used as the cosurfactant. The phase diagrams prove that the capacity for microemulsion formation varies in the following sequence: ACN = EtA > VAc > BuA > MMA > St > EHA. Conductometric and refractometric studies allowed us to evidence the formation of microemulsions with W/O, bicontinuous or O/W structure. Fluorescence studies give interesting informations on the stabilization capacity of the monomers dispersed by interaction with hydrophobic chain of the cosurfactant. H-NMR studies suggest that the monomers in microemulsions lie in regions with various polarities as function of their chemical nature. In polymerization initiated with benzoyl peroxide the minimum conversions were obtained in zones of composition where the initial microemulsions possess a bicontinuous microstructure. The reactions of degradative transfer of the increasing macroradicals account for these conversion modifications. For initiation with ammonium persulphate, its rate of decomposition depends on its ability to displace the proton bonded to the substituted vinylic carbon of the monomer. The productivity of this initiator varies within the sequence MMA > EtA > BuA > St > ACN > VAc. The consumption of the initiator, as induced by the monomer, depends on its chemical nature and on the solubilization site of the microemulsions.     

Transition-metal-free regioselective thiocyanation of phenols,anilines and heterocycles

An expedient direct and regioselective thiocyanation of phenols, anilines and heterocycles is described. Transformation is realized via the direct CH functionalization under transition metal free conditions at ambient temperature in excellent yields. Method proved to be monoselective and variety of functional groups tolerated the reaction conditions. The practicality of the protocol is demonstrated in gram scale synthesis of a precursor of PPAR δ agonist in excellent yield.