title: Polyethylene as a nonvolatile solid cosolvent phase for catalyst separation and recovery.
abstract: 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 °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 °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.
authors.affiliation: Department of Chemistry, Texas A&M University, College Station, Texas 77842-3012, USA.
authors.forename: Yanfei
authors.initials: Y
authors.lastname: Yang
authors.forename: Nilusha
authors.initials: N
authors.lastname: Priyadarshani
authors.forename: Tatyana
authors.initials: T
authors.lastname: Khamatnurova
authors.forename: Jakkrit
authors.initials: J
authors.lastname: Suriboot
authors.forename: David E
authors.initials: DE
authors.lastname: Bergbreiter
mesh_terms: D002384:Catalysis; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry* / Q000302:isolation & purification*; D010165:Palladium / Q000737:chemistry; D011090:Polyenes / Q000737:chemistry; D020959:Polyethylene / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013696:Temperature
chemical_list: D009942:Organometallic Compounds; D011090:Polyenes; D011108:Polymers; D012997:Solvents; D010165:Palladium; D020959:Polyethylene; C008967:polyisobutylene