Polymer Support Poly

S. Itsuno, M. Sakakura, and K. Ito, Polymer-supported poly(amino acids) as new asymmetric epoxidation catalyst of a,)3-unsaturated ketones, J. Org. Chem. 

To examine the differences in reactivity of various immobilized palladium pincer catalysts, small molecule, polymer-supported (poly(norbomene) - soluble, and Merrifield resin - insoluble), and silica-supported (SBA-15) pincer complexes were synthesized (Fig. 20.9) [44 6]. Both sulfur-containing (SCS) and phosphorous-containing (PCP) ligands were studied. 

Oscarson et al. [5] described the hydrolysis of compound 20 to 9 (89%) by treatment with KIO clay in methanol-water for 2 min under the action of microwave irradiation at 150 °C. Because polymer-supported reagents worked out well in acylation reactions, they also submitted 20 to microwave irradiation with polymer supported poly(4-vinylpyridinium-p-toluenesulfonate) (PPTS) in ethanol-water at 150 °C for 2 min and obtained 9 in 94% yield (Scheme 12.19). 

A more effecdve catalyst for the Hetuy reacdon is a polymer-supported base such as amberlyst A-31. Various fi-nitro alcohols can be obtained v/ith the help of amberlyst v/ith or without solvent fEq, 3,14, A recent report claims that amberlite IRA-430 COH-formi or DOWEX-1 COH-formi is more effecdve for the Henry reacdon than amberlyst A-31/ Poly-... 

Ionic liquids have already been demonstrated to be effective membrane materials for gas separation when supported within a porous polymer support. However, supported ionic liquid membranes offer another versatile approach by which to perform two-phase catalysis. This technology combines some of the advantages of the ionic liquid as a catalyst solvent with the ruggedness of the ionic liquid-polymer gels. Transition metal complexes based on palladium or rhodium have been incorporated into gas-permeable polymer gels composed of [BMIM][PFg] and poly(vinyli-dene fluoride)-hexafluoropropylene copolymer and have been used to investigate the hydrogenation of propene [21]. 

The structures of these ylide polymers were determined and confirmed by IR and NMR spectra. These were the first stable sulfonium ylide polymers reported in the literature. They are very important for such industrial uses as ion-exchange resins, polymer supports, peptide synthesis, polymeric reagent, and polyelectrolytes. Also in 1977, Hass and Moreau [60] found that when poly(4-vinylpyridine) was quaternized with bromomalonamide, two polymeric quaternary salts resulted. These polyelectrolyte products were subjected to thermal decyana-tion at 7200°C to give isocyanic acid or its isomer, cyanic acid. The addition of base to the solution of polyelectro-lyte in water gave a yellow polymeric ylide. 

Polychloromethylsulphonylbiphenyls, mass spectra of 154, 155 Polyenes, synthesis of 771 Polymerization, of sulphoxides 846 Polymer-supported reagents 928 Polymorphonuclear leukocytes 854 Poly(olefin sulphonejs, radiolysis of 916-922 Polysulphones, radiolysis of 913 Population analysis 14, 15, 21, 22 Propargylic sulphenates, rearrangement of 736-739... 

This review has shown that the analogy between P=C and C=C bonds can indeed be extended to polymer chemistry. Two of the most common uses for C=C bonds in polymer science have successfully been applied to P=C bonds. In particular, the addition polymerization of phosphaalkenes affords functional poly(methylenephosphine)s the first examples of macromolecules with alternating phosphorus and carbon atoms. The chemical functionality of the phosphine center may lead to applications in areas such as polymer-supported catalysis. In addition, the first n-conjugated phosphorus analogs of poly(p-phenylenevinylene) have been prepared. Comparison of the electronic properties of the polymers with molecular model compounds is consistent with some degree of n-conjugation in the polymer backbone. 

Even in solution the relative rigidity of the polymer support can play a significant role in the reactivity of attached functional groups. Contrasting studies conducted with chloromethylated derivatives of poly(arylene ether sulfone) (Tg 175°C), phenoxy resin (Tg= 65°C) and polystyrene (Tg= 105°C) allow evaluation of chain rigidity effects. We have shown that the rates of quaternization of chloromethylated poly(arylene ether sulfones) and phenoxy resin deviate from the anticipated second order process at... 

Polymer gels and ionomers. Another class of polymer electrolytes are those in which the ion transport is conditioned by the presence of a low-molecular-weight solvent in the polymer. The most simple case is the so-called gel polymer electrolyte, in which the intrinsically insulating polymer (agar, poly(vinylchloride), poly(vinylidene fluoride), etc.) is swollen with an aqueous or aprotic liquid electrolyte solution. The polymer host acts here only as a passive support of the liquid electrolyte solution, i.e. ions are transported essentially in a liquid medium. Swelling of the polymer by the solvent is described by the volume fraction of the pure polymer in the gel (Fp). The diffusion coefficient of ions in the gel (Dp) is related to that in the pure solvent (D0) according to the equation ... 

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

A more effective catalyst for the Henry reaction is a polymer-supported base such as amberlyst A-21. Various P-nitro alcohols can he obtained with the help of amberlyst with or without solvent (Eq. 3.14).25 A recent report claims that amberlite IRA-420 (OH-form) or DOWEX-1 (OH-form) is more effective for the Henry reaction than amberlyst A-21.26 Poly-... 

Three approaches have been tested, as already described above for inorganic supports. The first attempts concern the direct reaction of transition metal carbonyls with unmodified organic polymers like poly-2-vinyl-pyridine.61 62 However, this kind of anchoring is restricted to only a few complexes. Various polymers have been functionalized with donor groups 63-72 ligand displacement reactions using these afforded the corresponding immobilized complexes. Finally, tests with modified complexes and unmodified polymers are scarce because of the low stability of these complexes under the conditions of reactions. 

The most well-developed recent examples of catalysis concern catalysts for oxidation reactions these are essentially achiral or chiral metal-salen complexes. Taking into account a number of results suggesting the importance of a degree of mobility of the bound complex, Sherrington et al. synthesized a series of polymer-supported complexes in which [Mn(salen)Cl] units are immobilized in a pendant fashion by only one of the aromatic rings, to polystyrene or poly(methacrylate) resin beads of various morphology (Figure 6).78,79... 

Microwave-mediated transesterification of commercially available neat poly(styr-ene-co-allyl alcohol) with ethyl 3-oxobutanoate, ethyl 3-phenyl-3-oxopropanoate, and diethyl malonate provided the desired polymer-supported /i-dicarbonyl compounds (Scheme 12.18) [65]. Multigram quantities of these interesting building blocks for heterocycle synthesis were obtained simply by exposing the neat mixture of reagents to microwave irradiation in a domestic microwave oven for 10 min. 

The multipolymer enzymatic resolution of soluble polymer-supported alcohols 42 and 43 was achieved using an immobilised lipase from Candida Antarctica (Novozym 435). The R-alcohol was obtained in enantiomerically pure form (>99% ee) after its cleavage from the poly(ethylene) glycol (PEG) scaffold . The achiral hydantoin- and isoxazoline-substituted dispirocyclobutanoids 47 were produced using both solution and solid-phase synthesis <00JOC3520, OOCC1835>. 

Mdleleni and coworkers137 anchored RhCl3 onto several porous aminated polymers. As displayed in Table 43, the best polymer support was found to be poly (4-vinylpyridine). Conditions T = 100 °C Pco = 0.9 atm RhCl3 3H20 = 5 x 10 5 mol solvent/H20 = 4/1 v/v. 

Polymer-supported tin hydrides are being increasingly used to avoid the separation problem,407 12 and the reagent Bu2SnHLi, described above, is useful for attaching a stannyl hydride group to a polymer such as poly(4-chlorobutyl-styrene).397 The use of a non-cross-linked, soluble polystyrene has also been recommended.288... 

In 1993 Bergbreiter prepared two soluble polymer-supported phosphines that exhibited an inverse temperature-dependent solubility in water [52]. Although PEG-supported phosphine undergoes a phase-separation from water at 95-100 °C, the PEO-poly(propylene oxide)-PEO supported catalyst was superior as it is soluble at low temperatures and phase-separates at a more practical 40-50 °C. Treatment of a diphenylphosphinoethyl-terminated PEO-PPO-PEO triblock copolymer... 

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