Methods for removal of residual catalyst from polymers prepared by ring opening metathesis polymerization

Abstract

Methods for removing the residual Grubbs' third generation catalyst from polymers prepared by ring opening metathesis polymerization are reported. Two strategies were investigated for reduction of the residual catalyst in the final polymer product. The first strategy involved the use of heterogeneous functionalized particles to scavenge the catalyst from the solution. Filtration of the particles followed by precipitation produced polymers with 10-60 ppm residual catalyst, depending on the type of particle used, surface functional groups, and number of equivalents. The second strategy used small organic molecules that could coordinate to the metal species and modify the solubility of the catalyst, facilitating partitioning of the catalyst into the precipitation solvent. Several types of molecules with varied functionality reduced the residual catalyst level to 30-120 ppm, depending on the loading. Hydrogenation of the polymer backbone followed by precipitation lowered the residual Ru content from 195 ppm to 10 ppm, suggesting that the difficulty of completely removing the catalyst could be a result of coordination of the metal species to the double bonds in the polymer backbone. Reducing the amount of trace catalyst significantly improved the oxidative stability of the polymer. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 5752-5757, 2010

Characterization of large molecular weight ester‐functionalized norbornene and hydroxylated norbornane carboxylic acid polymers prepared by ring‐opening metathesis polymerization

“…Yields for the polymerization reactions were typically quantitative, though lower yields were occasionally observed (60–80%) for the low molecular weight polymers due to losses during purification. Remaining Grubbs catalyst was scavenged using N ‐acetyl‐ L ‐cysteine 16. Polymer 2 was then hydroxylated with hydrogen peroxide and trifluoroacetic anhydride under reflux conditions to produce polymer 3 with yields ranging from 75% to 85%.…”

A multivalent inhibitor of the DC-SIGN dependent uptake of HIV-1 and Dengue virus

“…After reaction completion the mixtures were loaded directly on SEPHADEX LH-20 columns (55 cm x 3.5 cm, MeOH as eluent) to purify the products by size exclusion chromatography. In order to remove copper residues from the products, reverse phase chromatography was performed (C18, eluent: H 2 O with gradients of MeOH or MeCN) or to the solution of product in MeOH a metal scavenger [30] (such as Quadrasil TM MP) was added and stirred for 5 min. The scavenger was filtered off through a cotton pad and the filtrate was concentrated to obtain the product.…”

“…The dendrimers were isolated from the reaction mixtures by size exclusion chromatography on Sephadex LH20 matrix using MeOH as eluent. Residual copper was removed either by reverse phase chromatography (C18) or using metal scavengers (Quadrasil MP) [30]. All materials were found to be stable for months in water solution and were fully characterized by MALDI-MS analysis (sinapinic acid or DBA) and by 1 H and 13 C-NMR spectroscopy.…”

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“…These observations were reproducible. No such phenomenonw as present for isocyanides I and II.T his may be explained by the fact that two isocyanide groups will bind to each atom of ruthenium, [57] whereas compound III has three such groups.I na mountsl ower than one equivalent, compound III probablyf orms polycentric,m acromolecular complexes with ruthenium, which are easier to remove than the small-molecule complexes formed when III is used in excess. However,n oa ttempt was made to furtherc orroborate this hypothesis.…”

“…[57] Most of these compounds are commercially available, but none of them satisfya ll of the above conditions. Their mosti mportant disadvantages are the necessity of using them in large excess (more than 10 equiv with respectt ot he metal), al ong bindingt ime (more than 1h), andh igh residual ruthenium content (above 10 ppm).…”