Synthesis of aromatic polyesters using polymeric catalysts having quaternary ammonium salt groups

The preparation of polyester (PQ) and copolyester (PQ-DIOL) catalysts having quaternary ammonium groups was performed, and an aromatic polyester (PEA) was directly synthesized from isophthaloyl chloride and diphenolic acid by aqueous/organic interfacial polycondensation using these polymer catalysts. The yield and molecular weight of the polyester were affected by the structure of the pendant quaternary ammonium groups.     

Soluble polymer-supported catalysts containing pendant quaternary onium salts for the addition reaction of oxiranes with carbon dioxide

The addition reaction of oxiranes ( 15a-d ) with carbon dioxide (CO₂) was carried out using 1 mol % of soluble polymer-supported quaternary onium salts as catalysts under atmospheric pressure. The reaction of 15a-d with CO₂ proceeded very smoothly to give the corresponding five-membered cyclic carbonates ( 16a-d ) in high yields at 90-100°C. The catalytic activity of the soluble polymer-supported quaternary onium salts was strongly affected by the following factors: kind of reaction solvent, degree of introduction of the pendant onium salt residues in the polymer chain, and type of alkyl group on the onium salts due to the balance between lipophilicity and steric hindrance of the onium salt residue. Furthermore, these soluble polymer-supported quaternary onium salts were found ordinarily to have higher catalytic activity than low molecular weight quaternary onium salts under the same reaction conditions. It was also found that the rate of reaction was proportional both to catalyst concentration and to oxirane concentration. © 1995 John Wiley & Sons, Inc.     

Novel quaternary ammonium borates as latent catalysts for epoxy–phenolic resins

Novel tetrabutylammonium tetrakis(substituted benzoyloxy)borate salts ( 1a – 1d ) were synthesized by the reaction of tetrabutylammonium tetraphenylborate and corresponding substituted benzoic acids. Polyaddition reactions of diglycidyl ether of bisphenol A (DGEBA) and 4,4′‐bisphenol F (44BPF) or bisphenol F (BPF‐D) with the ammonium borates were investigated as model reactions of epoxy/phenol–novolac resin systems with respect to the thermal latency and storage stability of the catalyst. The polyaddition of DGEBA/44BPF with the ammonium borates in diglyme at 150 °C for 6 h proceeded up to 84–94% conversions and gave polymers with number‐average molecular weights of 3750–5750, whereas the polyaddition at 80 °C for 6 h gave less than 9% conversions. The catalytic activity of ammonium borates 1a – 1d depended on the substituent of the phenyl group of the borates, and the order of activity was 1b (p‐OMe) > 1a (? H) > 1c (p‐NO₂) > 1d [3,5‐(NO₂)₂]. The ammonium borate catalyst with the substituent that yielded lower acidity of the corresponding substituted benzoic acid tended to reveal higher activity. In comparison with tetrabutylammonium bromide (TBAB) as a conventional ammonium salt, 1a – 1d revealed better thermal latency. The storage stability of DGEBA/BPF‐D with the ammonium borate catalysts in bulk at 40 °C was better than that with TBAB. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2689–2701, 2002     

Soluble polymer-supported catalysts containing azo dyes

[structure: see text] Azo benzene derivatives were incorporated into soluble polymer-bound catalysts by two different approaches. The first was to attach the dye to the polymer-bound catalysts, using the dye as an innocent spectator to study the phase preference, concentration, and recoverability of a catalyst. The second approach used an azo dye as a ligand to form an effective soluble polymer-bound Pd(II) catalyst for Heck reactions.     

Enantioselective allylic alkylation using polymer-supported palladium catalysts

Chiral 2′-(4″,5″-dihydro-2″-oxazolyl)-6′-(1-hydroxyalkyl)pyridines were grafted via ester-linkages directly to cross-linked polystyrene and to polyethyleneglycol-containing resins TentaGel and ArgoGel functionalized with carboxylic acid groups or via spacers containing a carboxylic acid group. The polymeric ligands were used in the palladium-catalyzed substitution of rac-1,3-diphenyl-2-propenyl acetate with dimethyl malonate. The enantioselectivities (up to 80% ee) were similar to those observed employing an analogous monomeric catalyst.     

Novel polymer-supported chiral catalysts for asymmetric synthesis

Hydroxy amino acid monomers 3, 5 and amino acid monomers 10, 11 were prepared. Suspension polymerization of these chiral monomers with styrene and crosslinking agent afforded insoluble chiral polymers which were used as chiral ligands of the enantioselective Diels-Alder reaction catalysts. A continuous flow system using polymeric catalyst was also successfully achieved in the same reaction.     

Efficient soluble polymer-supported sharpless alkene epoxidation catalysts

High chemical yields and good enantiomeric excesses are obtained by using soluble polymer-supported tartrate ester in the epoxidation of trans-hex-2-en-1-ol using Ti(OPri)4/tert-butyl hydroperoxide.     

Macroporous polystyrene-supported quaternary ammonium salt catalysts for the addition of carbon dioxide to glycidyl methacrylate

In the present study, the synthesis of (2-oxo-1,3-dioxolan-4-yl)methyl methacrylate (DOMA) from carbon dioxide and glycidyl methacrylate (GMA) was investigated in a semi-batch reactor using macroporous polystyrene beads containing pendant quaternary ammonium salt catalysts. The catalysts were prepared by partial copolymerization of styrene (ST) and divinylbenzene (DVB) with isooctyl alcohol, and then by copolymerization with vinylbenzyl chloride (VBC). Quaternization of the pendant chloromethyl groups was carried out by using trialkylamines. The catalytic activity of the macroporous polymer was influenced by VBC and isooctyl alcohol concentration, and by the structure of trialkylamine. A kinetic study was also carried out to better understand the reaction steps. This revised version was published online in June 2006 with corrections to the Cover Date.     

合成丙交酯的催化剂研究进展

丙交酯作为合成聚乳酸的重要中间体,它的制备效率是影响两步法聚合高分子量PLA的关键因素。寻找高效催化剂是其中一个重要的解决方案,本文就与日俱增交酯合成过程中不同催化剂体系的选择进行了综述,未来的工作应放在催化剂和制备效率上。     

Mathematical modeling of heterogeneous catalysis involving polymer-supported catalysts

This study reports the mathematical modeling of catalytic reaction systems involving polymer-supported catalysts. Differential mass balances were applied to species and the partial differential equations were solved through the method of lines in MATLAB®. Etherification and esterification reactions were studied with the present model and validation was performed with literature data, providing fair agreement. Furthermore, the model proved capable of predicting concentration gradients along the catalyst particles, providing an interesting level of detail to represent catalytic heterogeneous systems.     

组合化学法筛选聚苯乙烯固载季铵盐相转移催化剂研究(I)

利用组合化学方法合成了一个含有60种不同结构的聚苯乙烯固载季铵盐相转移催化剂的催化剂库,以有外加碱条件下亲核取代反应为探针反应,利用迭代法从中筛选出了活性最高的催化剂,建立了一种快速合成和筛选聚苯乙烯固载季铵盐相转移催化剂的方法。     

Highly efficient heterogeneous polymer-supported Sharpless alkene epoxidation catalysts

More widespread, and cost effective, use of soluble transition metal complex asymmetric catalysts would be achieved if highly efficient heterogeneous analogues could be developed. We now report the synthesis of branched/crosslinked poly(tartrate ester)s and their use as heterogeneous ligands for the complexation of Ti(OⁱPr)₄, and use of the resulting insoluble catalysts in the asymmetric epoxidation of a range of trans-allylic alcohols employing t-butylhydroperoxide (tBHP) as the oxidant. Isolated yields of epoxides of up to 80%, with enantiomeric excesses up to 98% have been achieved. Removal and recovery of the polymer catalyst is by simple filtration at the end of reactions. The influence of the ratio of polymer-ligand–titanium, and the polymer backbone molecular architecture on the activity and enantioselectivity of the catalysts has been assessed. Typically polymer branching ratios of 3–11% and a polymer-ligand:titanium ratio of 2:1 yield the optimum results.     

Recyclable polymer-supported Pd catalysts for aryl amination reactions

Polymer-supported palladium catalysts were prepared from three commercially available phosphine-functionalised polymers (PS-PR₂), Pd₂(dba)₃ and P(t-Bu)₃. Catalyst stability was investigated using VT ³¹P NMR spectroscopy. One of the catalysts can be reused in the amination of bromobenzene and chlorotoluene, up to three times, without loss in yield. Recyclability of the catalysts is dependent on the method of preparation and the nature of the polymer-bound phosphine.     

Synthesis of thioether using dimethyloctyl(3-sulfopropyl)ammonium betaine and di-active site quaternary ammonium salt as new phase-transfer catalysts

The novel phase-transfer catalysts S-8 (dimethyloctyl(3-sulfopropyl) ammonium betaine) and DB-2 (di-active site quaternary ammonium salts) were synthesized and employed as the phase-transfer catalysts for synthesizing thioethers from various alkyl bromides of high conversion. This revised version was published online in August 2006 with corrections to the Cover Date.     

Simply assembled and recyclable polymer-supported olefin metathesis catalysts

Polymer-supported ruthenium catalysts (PCy(3))(2)Ru(=C(H)Ph)Cl(2), (PCy(3))Ru(IMes)(=C(H)Ph)Cl(2), and (PCy(3))Ru(SIMes)(=C(H)Ph)Cl(2), where IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene and SIMes = 1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene, have been prepared and found to be effective "boomerang" catalysts for ring-closing metathesis. They are recyclable, show comparable or better reactivity than their homogeneous counterparts, tolerate functional groups, and perform very well with dienes and moderately well with highly hindered substrates.     

Microwave synthesis of quaternary ammonium salts

The microwave synthesis of several quaternary ammonium salts is described. The synthesis provides comparable or better yields than published methods with reduced reaction times and in the absence of solvent.     

Solid-phase extraction of quaternary ammonium herbicides

This paper highlights recent advances in the solid-phase extraction (SPE) of quaternary ammonium herbicides in water, soil, plant and biological samples. After a brief introduction summarizing the properties of quaternary ammonium herbicides and the difficulties involved in measuring them, attention is paid primarily to solid supports used for isolation and concentration, pre-treatments required for the different matrices, and eluents applied for quantitative desorption of these analytes. The determination techniques used after SPE and applications of the proposed SPE methodology are also briefly discussed.     

Chemoselective epoxidation of dienes using polymer-supported manganese porphyrin catalysts

Manganese porphyrin catalysts supported on different polymer resins were assessed in the selective epoxidation of three dienes. The recyclability of the catalysts was examined.     

Water-soluble organometallic catalysts from carbohydrates. 2. A strategy for the preparation of catalysts with pendant quaternary ammonium groups using D-salicin

A series of water-soluble chelating bis-phosphinite ligands have been prepared from D-salicin (2-(hydroxymethyl)phenyl beta-D-glucopyranoside). The 4- and 6-hydroxyl groups of salicin were protected as a cyclic ketal. Mitsunobu reaction with phthalimide at the benzylic position was used to install the aminomethyl side-chain in the C(1)-aromatic substituent. Formation of the bis-2,3-O-diarylphosphinite was accomplished by reaction of the resulting diol with chlorodiarylphosphine. Quaternization with Meerwein's salt (Me(3)O(+) BF(4)(-)) followed by reaction with Rh(+)(COD)(2) BF(4)(-) gave precatalysts with limited aqueous solubility. Deprotection of the ketal group with acidic resin in methanol gave water-soluble cationic Rh complexes that are competent to carry out highly efficient hydrogenation of acetamidoacrylic acid derivatives in organic, aqueous, or biphasic media. However, enantioselectivities of these reactions in neat aqueous or biphasic media are generally lower than those observed in organic medium.