Poly styrene supports

Zheng, X. Jones, C. W. Week, M. (2006) Poly(styrene)-supported Co-salen eomplexes as effieient recyclable catalysts for the hydrolytic kinetic resolution of epiehlorohydrin, Chem. Eur. J., 12 576 - 583. 

Figure 4 Kinetic plot of the ffKR of rac-epichlorohydrin using the homogeneous and poly(styrene) supported Co(III) salen catalysts.

Poly (norbornene)-supported Co(III)-Salen complexes (44) and poly (styrene)-supported Co(III)-Salen complexes (45,46) were synthesized via newly developed procedures. In particular, a new, high-yielding, one-pot synthesis of non-symmetrical salens was developed (46). Hydrolytic kinetic resolutions were carried out at room temperature and the products were characterized by chiral GC. 

Table 3.7 Preparation of substituted aza-heterocycles catalysed by poly-styrene-supported-TBD (l,5,7-triazabicyclo[4.4.0]dec-5-ene).

Preparation. The PS-TsA (eq 1) is prepared in one step from poly styrene-supported benzenesulfonyl chloride (100-200 mesh, 1.5-2.0 mmol/g). Typically, 1.5 mmol of resin is swollen in DMF and then treated with 3.0 mmol of NaNs dissolved in H2O (1.0 mL) and diluted with DMF (7 mL). After 16 h the resin is washed with H2O (5x5 mL), DMF (5x5 mL), and finally with CH2CI2 (3x5 mL) and dried under vacuum at 40 °C. The loading of PS-TsA was determined to be 1.0-1.5 mmol/g by combustion analysis of two different batches. The resin is stored at rt and appears to be stable over an indefinite period of time. FTIR of the resin shows a strong band for the azide functionality at 2130 cm-. ... 

As an example, consider the use of PVPy as a solid poison in the study of poly(noibomene)-supported Pd-NHC complexes in Suzuki reactions of aryl chlorides and phenylboroiuc acid in DMF (23). This polymeric piecatalyst is soluble under some of the reaction conditions employed and thus it presents a different situation from the work using porous, insoluble oxide catalysts (12-13). Like past studies, addition of PVPy resulted in a reduction in reaction yield. However, the reaction solution was observed to become noticeably more viscous, and the cause of the reduced yield - catalyst poisoning vs. transport limitations on reaction kinetics - was not immediately obvious. The authors thus added a non-functionalized poly(styrene), which should only affect the reaction via non-specific physical means (e.g., increase in solution viscosity, etc.), and also observed a decrease in reaction yield. They thus demonstrated a drawback in the use of the potentially swellable PVPy with soluble (23) or swellable (20) catalysts in certain solvents. 

Chemical composition of packings. Today, a wider variety of different support materials is available from which to choose. Silica is still widely used, though preparative grades often possess a relatively wide particle size distribution as compared to polymer-based supports. One serious limitation of silica-based supports is the low stability of silicas to alkaline pH conditions, which limits use of caustic solutions in sanitization and depyrogenation. Polymer-based supports, which include poly(styrene-divi-nyl benzene)- or methacrylate-based materials, are widely available and have gained increased acceptance and use. Nonfunctionalized poly(styrene-divinyl... 

Poly(styrene—divinylbenzene) copolymers can be used as catalyst supports. Attachment of catalytic groups to the polymer supports can be achieved by... 

A method for microwave-assisted transesterifications has been described by Van-den Eynde and Rutot [73], The authors investigated the microwave-mediated deriva-tization of poly(styrene-co-allyl alcohol) as a key step in the polymer-assisted synthesis of heterocycles. Several /i-ketoesters were employed in this procedure and multigram quantities of products were obtained when neat mixtures of the reagents in open vessels were subjected to microwave irradiation utilizing a domestic micro-wave oven (Scheme 7.65). The successful derivatization of the polymer was confirmed by IR, 1H NMR, and 13C NMR spectroscopic analyses. The soluble supports... 

Zhang developed a monolithic poly(styrene-co-divinylbenzene) CEC column in which the EOF is supported by carboxyl groups of polymerized methacrylic acid [ 133]. Using benzene as a probe, column efficiencies of 90,000 -150,000 were observed within a flow velocity range of l-10cm/min (0.2-1.7 mm/s). Different families of compounds such as phenols, anilines, chlorobenzenes, phenylendi-amines, and alkylbenzenes were well separated typically in less than 5 min using 20 cm long columns. 

The reaction is reversible and therefore the products should be removed from the reaction zone to improve conversion. The process was catalyzed by a commercially available poly(styrene-divinyl benzene) support, which played the dual role of catalyst and selective sorbent. The affinity of this resin was the highest for water, followed by ethanol, acetic acid, and finally ethyl acetate. The mathematical analysis was based on an equilibrium dispersive model where mass transfer resistances were neglected. Although many experiments were performed at different fed compositions, we will focus here on the one exhibiting the most complex behavior see Fig. 5. 

R. E. Moore, L. Licklider, D. Schumann, T. D. Lee A microscale electrospray interface incorporating a monolithic, poly(styrene-divinylbenzene) support for online liquid chromatography/tandem mass spectrometry analysis of peptides and proteins. Anal. Chem. 1998, 70, 4879-4884. 

The first system is based on a poly (norbornene)-supported Co salen and the second system is based on a poly(styrene) backbone. For the poly (norbornene) system, a homopolymers and several different copolymers were prepared (44), with varying fractions of Co salen side-chains and spacer side-chains (Figure 3, copolymer la-c and homopolymer Id). For the poly (styrene) system, both homopolymers of salen-containing monomers and copolymers with styrene (45,46) were prepared (Figure 3, copolymer 2a-c and homopolymer 2d). 

Spontaneous polymerization of 4-vinyl pyridine in the presence of polyacids was one of the earliest cases of template polymerization studied. Vinyl pyridine polymerizes without an additional initiator in the presence of both low molecular weight acids and polyacids such as poly(acrylic acid), poly(methacrylic acid), polyCvinyl phosphonic acid), or poly(styrene sulfonic acid). The polyacids, in comparison with low molecular weight acids, support much higher initial rates of polymerization and lead to different kinetic equations. The authors suggested that the reaction was initiated by zwitterions. The chain reaction mechanism includes anion addition to activated double bonds of quaternary salt molecules of 4-vinylpyridine, then propagation in the activated center, and termination of the growing center by protonization. The proposed structure of the product, obtained in the case of poly(acrylic acid), used as a template is ... 

---