摘要:

AbstractLinear and cross‐linked copolymers of 4‐vinylpyridine borane (4VP·BH3) with 4‐vinyl‐pyridine (4VP) and with styrene were prepared and used as polymeric reducing reagents towards various aldehydes and ketones. The monomer 4VP·BH3could only be obtained in a mixture with 4VP, from which the IR data are

ISSN:0360-8905    

DOI:10.1002/polc.5070470103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractVarious forms of cross‐linked polystyrene were compared as to their effectiveness as carriers‐diluents in reactions of carboxylic ester enolates. The polymers compared were microporous (2 % divinylbenzene), “popcorn,” and macroporous polystyrenes. In the acylation by acyl halides of polymer ester enolates, higher yields were obtained and less self‐condensation occured with the popcorn polymer as carrier than with the microporous polystyrene. Popcorn and microporous polymers gave similar results in the alkylation of polymer ester enolates. The macroporous polymers (both commercial and synthetized) gave much poorer results in this latter reaction (low yields and more self‐condensation). Popcorn and microporous polystyrenes gave equally good results in the mixed ester condensation of two esters attached to a common polymer backbone. When polymer esters were treated with base without subsequent addition of electrophile, 10‐15% of intrapolymeric self‐condensation occurred with all three types of polymer, when ester concentration was 0.1‐0.15 mmole/ g. Under similar conditions, the analogoussolubleester self‐condensed to the extent of 67 %. It is concluded that under the proper conditions, all of the cross‐linked polystyrenes are capable of inhibiting mutual interactions of attached molecules. These conditions are low concentration and low molecular weight of attached molecules, and

ISSN:0360-8905    

DOI:10.1002/polc.5070470104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractPolymers of ethylene methacrylate, toluene‐, and benzenesulfonate are shown to be strongalkylating agents. Their polymer‐analogous reaction with most nucleophiles proceeds smoothly under conditions comparable to those of low molecular analogs. The nucleophiles used successfully were of the nitrogen type: amines, pyridine, phthalimidate, azide; or oxygen: alkoxide, phenolate, carboxylate; sulfur: thioacetate, thiocyanate, thiourea; and other types: iodide. Further reaction of some of these derivatives, e.g., hydrolysis to thiol or amine, proceeds as expec

ISSN:0360-8905    

DOI:10.1002/polc.5070470105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractThis paper presents the results of investigations on thermal polycyclocondensation of polyhydrazides to corresponding poly‐1,3,4‐oxadiazoles. A limiting character of conversion is associated with the mobility of polymeric chains due to the fact that they become rigid by conversion of linear hydrazide fragments into cyclic 1,3,4‐oxadiazole ones, as well as to an increasing content of the latter in the course of conversion. Hence, the kinetics of the solid‐phase polycyclization of polyhydrazides is determined not only by the reactivity of groups participating in cyclization, but also by some factors indicating the effect of the structure on the starting polymeric compound and that of the structur

ISSN:0360-8905    

DOI:10.1002/polc.5070470106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

Abstract2,6‐Xylenol was oxidatively polymerized by Cu‐poly (vinylpyridine) (PVP) complex or Cu‐partially‐quaternized PVP (QPVP) complex in a homogeneous dimethylsulfoxide solution, and the mechanism of the catalysis of the polymeric Cu complexes was discussed. The polymerization rate increased in the following order: Cu‐pyridine

ISSN:0360-8905    

DOI:10.1002/polc.5070470107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractThe catalytic cycle of the Cu‐pyridine complex catalyzed polymerization of 2,6‐xylenol was divided into four elementary processes: the coordination of the substrate, the electron transfer from the substrate to the cupric ion, the dissociation of the activated substrate, and the reoxidation of the catalyst. Rate constants of each elementary reaction,k1, ke, kd, andko, were determined spectroscopically by the stopped‐flow method. The approximate magnitudes of each rate constant werek1: 10 (1·mole−1·minp−1),ke:10−2(min−1), andko, 102(min−1), respectively. Thus, it was considered that thekeor thekdprocess was the rate‐determining step, but the latter could not be measured in this procedure. The rate constants were affected by the species of the solvent. With a few exceptions of the solvent which had coordinating ability,k1andkeincreased andkodecreased with the polarity of the solvent. The effects of the polymer‐ligand on each elementary reaction were also studied in the polymerization catalyzed by the Cu‐partially‐quaternized poly(vinylpyridine) complex.k1andkowere smaller andkewas larger than those of the monomeric analog. It was interpreted that thekestep was accelerated by the electrostatic fi

ISSN:0360-8905    

DOI:10.1002/polc.5070470108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractL‐asparaginase (ASNase) fromEscherichia coli(EC) II andErwinia carotovora(Erw. carot.) has been chemically coupled to poly(methyl methacrylate) (PMMA) via the bifunctional coupling agents γ‐aminopropyltriethoxysilane and glutaraldehyde.The level of bound activity was about 2 and 6 IU/100 cm2, respectively. The immobilized asparaginases were successfully used in previously reportedin vivoexperiments. Certain kinetic characteristics such as pH profile and temperature dependence were unafected by the immobilization process Both bound asparaginase's apparentKmwere greater than the native enzyme's value by approximately an order of magnitude. The apparentKmfor the EC ASNase was approximately the same in buffer solutions and in pooled canine b

ISSN:0360-8905    

DOI:10.1002/polc.5070470109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractFixation of the prosthetic groups of hemoproteids on synthetic macromolecular carriers is important from the viewpoint of biocatalytic investigations.Fe‐porphyrins which contained isocyanate sidechains have been prepared by two methods. This isocyanate reacted in pyridine as the solvent at room temperature with cross‐linked poly(2‐hydroxyethylmethacrylate) and with Sephadex LH 20, a hydroxypropyl group containing a carrier.The identity of the new Fe‐porphyrin derivatives and coupling products with synthetic carriers could be ascertained by elementary analysis and by absorption spectroscopy in the visible and infrared region.The properties of mesohemin IX are retained after covalent binding to the carriers. At near neutral pH, a spectrum typical of alkaline hematin (parahematin) occurred. At pH 1.6, the spectrum of acidic hematin appears. The ligand binding ability to CN−and imidazole has been retained. The reduction of the Fe(III) with sodium dithionite is possible. The coupling products show peroxidatic

ISSN:0360-8905    

DOI:10.1002/polc.5070470110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractGel beads of excellent mechanical properties are obtained by copolymerization of methacrylic acid anhydride with acrylamide using ethyleneglycoldimethacrylate or N, N′‐methylene‐bis (methacrylamide) as a cross‐linker.When protein is covalently bound to the anhydride groups of the beads, residual anhydride groups are hydrolyzed to form an anionic matrix (AM). The hydrophilic gel beads are stable to 1MNaOH, mechanical stirring, and dehydration by lyophilization or organic solvents. Proteases, nucleases, and amylases bound to AM are efficient catalysts in breaking down high molecular weight substrates.As far as the interaction of AM with biomacromolecules at pH 7.5 in 0.05Mphosphate buffer is concerned, polyanions like DNA or tRNA are strictly excluded from the gel volume, whereas cationic polymers like basic proteins are strongly absorbed even at an ionic strength of 0.3. Little or no interaction is observed with neutral biop

ISSN:0360-8905    

DOI:10.1002/polc.5070470111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractDNase‐free protease covalently bound to hydrophilic anionic gel beads1can be used to isolate DNA from animal tissue homogenate by simply degrading the protein moiety and precipitating the DNA with isopropanol from the supernatant, the yield being close to 80%. Glucoamylase bound to AM retains 100% activity as compared to the free enzyme. Thus, 30 % solutions of dextrins in water were degraded to glucose and the procedure was repeated with the same beads for 42 times without apparent loss of enzyme activity. From a technical point of view, this system is more efficient than using the free enzym

ISSN:0360-8905    

DOI:10.1002/polc.5070470112

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY