Using Polyisobutylene as Nonpolar Phase Solubilizing Agents and Polymer Supports for Catalysts and Reagents
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Diethylamine terminated PIB and N,N-diethyl-N-methylammonium terminated PIB oligomers are used to help solubilize different types of anions in nonpolar solvents. Metal salts are important in many organic transformations, yet their uses in organic solvents and more particularly in hydrocarbon solvents have not been fully explored due to their insolubility in these media. Although much work has been done to solve this problem by using phase transfer catalysts, such as tetrabutylammonium salts, the solubility of these salts is still limited in very nonpolar solvents. Moreover, these salts are often hard to isolate from the product and are not recyclable. This work describes the synthesis of diethylamine terminated PIB and N,N-diethyl-N-methylammonium terminated PIB oligomers and their use to help solubilize oxidative catalysts, such as polyoxometalate clusters and perruthenate anions, in heptane. The oxidation reactions were found to be efficient, and the PIB-supported catalysts can be easily recovered by biphasic separation and recycled multiple times. We have also explored using a N,N-diethyl-N-methylammonium terminated PIB oligomer to do simple reactions, exploring both their competence and how the hydrocarbon solvent affects a conventional reaction’s kinetics. This was accomplished using studies of the rates of SvN2 reactions with various kinds of anions in conventional solvents like DMF, MeCN, MeOH, and in heptane using a N,N-diethylamine-N-methylammonium terminated PIB oligomer. The reaction in heptane is assumed to have minimal solvent effects because it is nonpolar and has no hydrogen bonding. Moreover, the catalytic activity of the N,N-diethyl-N-methylammonium terminated PIB oligomer was also investigated in a solid/liquid phase catalysis. N,N-diethyl-N-methylammonium terminated PIB oligomer was used as a phase solubilizing catalyst to solubilize anions from solid metal salts in heptane. We also expanded our work to use poly(ɑ-olefins) (PAOs) as alternatives for low molecular weight conventional alkane solvents. Not only are poly(ɑ-olefins) nontoxic and nonvolatile, the leaching of PAOs into the polar phase was less than the leaching of heptane into a polar phase. This feature is important for catalyst recycling. In addition to the oxidation reactions using POM cluster and perruthenate anion, we also investigated another class of oxidizing agents, hypervalent iodine compound. 2-Iodoxybenzoic acid (IBX) was immobilized on to PIB oligomer by a covalent ester linkage. The PIB-supported IBX was efficient in oxidizing various types of alcohols. It can also be easily recovered by simple biphasic separation and can be recycled multiple times.
hypervalent iodine reagent
Samunual, Peerada (2017). Using Polyisobutylene as Nonpolar Phase Solubilizing Agents and Polymer Supports for Catalysts and Reagents. Doctoral dissertation, Texas A & M University. Available electronically from