Polyethylene as a Nonvolatile Solid Cosolvent Phase for Catalyst Separation and Recovery

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• 作者：Yanfei Yang ; Nilusha Priyadarshani ; Tatyana Khamatnurova ; Jakkrit Suriboot ; David E. Bergbreiter
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：September 12, 2012
• 年：2012
• 卷：134
• 期：36
• 页码：14714-14717
• 全文大小：238K
• 年卷期：v.134,no.36(September 12, 2012)
• ISSN：1520-5126

文摘

The studies described here show that a relatively low molecular weight, narrow polydispersity polyethylene (PE) wax (Polywax) can serve as a nontoxic and nonvolatile alternative to alkane solvents in monophasic catalytic organic reactions where catalysts and products are separated under biphasic conditions. In this application, a polymer that is a solid at room temperature substitutes for a conventional alkane solvent at ca. 80 掳C. In addition to the advantages of being a nonvolatile, nontoxic, reusable solvent, this hydrocarbon polymer solvent, like heptane, can sequester nonpolar soluble polymer-bound catalysts after a reaction and separate them from products. The extent of this separation and its generality were studied using polyisobutylene (PIB)- and poly(4-dodecylstyrene)-bound dyes and PE-bound Pd allylic substitution catalysts, PIB-bound Pd cross-coupling catalysts, and PE- and PIB-bound metathesis catalysts. Catalytic reactions were effected using single-phase reaction mixtures containing Polywax with toluene, THF, or THF/DMF at ca. 80 掳C. These solutions either separate into two liquid phases on addition of a perturbing agent or separate as a solid/liquid mixture on cooling. The hydrocarbon polymer-bound dyes or catalysts either separate into the hot liquid Polywax phase or coprecipitate with Polywax and are subsequently isolated as a nonvolatile Polywax solid phase that contains the dye or the recyclable catalyst.