Polyethylene as a Nonvolatile Solid Cosolvent Phase for Catalyst Separation and Recovery.
Summary of "Polyethylene as a Nonvolatile Solid Cosolvent Phase for Catalyst Separation and Recovery."
The studies described here show that relatively low molecular weight, narrow polydispersity polyethylene (Polywax) can serve as a nontoxic and nonvolatile alternative to alkane solvents in monophasic catalytic organic reactions carried 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 ºC. In addition to 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 phase 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 separate into the hot liquid Polywax phase or coprecipitate with Polywax and are subsequently isolated as a solid nonvolatile Polywax solid phase that contains the dye or the recyclable catalyst.
Affiliation
Journal Details
This article was published in the following journal.
Name: Journal of the American Chemical Society
ISSN: 1520-5126
Pages:
Links
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/22924456
- DOI: http://dx.doi.org/10.1021/ja306719j
Medical and Biotech [MESH] Definitions
Chromatography, Gas
Fractionation of a vaporized sample as a consequence of partition between a mobile gaseous phase and a stationary phase held in a column. Two types are gas-solid chromatography, where the fixed phase is a solid, and gas-liquid, in which the stationary phase is a nonvolatile liquid supported on an inert solid matrix.
Gels
Colloids with a solid continuous phase and liquid as the dispersed phase; gels may be unstable when, due to temperature or other cause, the solid phase liquefies; the resulting colloid is called a sol.
Solid Phase Extraction
An extraction method that separates analytes using a solid phase and a liquid phase. It is used for preparative sample cleanup before analysis by CHROMATOGRAPHY and other analytical methods.
Suspensions
Colloids with liquid continuous phase and solid dispersed phase; the term is used loosely also for solid-in-gas (AEROSOLS) and other colloidal systems; water-insoluble drugs may be given as suspensions.
Polyethylene
A vinyl polymer made from ethylene. It can be branched or linear. Branched or low-density polyethylene is tough and pliable but not to the same degree as linear polyethylene. Linear or high-density polyethylene has a greater hardness and tensile strength. Polyethylene is used in a variety of products, including implants and prostheses.
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