Polymer catalyzed

Table 1 Classification of enzymes respective enzymes and in vitro production of typical polymers catalyzed by...

Figures I and II show a comparison of the reaction profile for PPY and polymer catalyzed hydrolysis for p-nitrophenylacetate and p-nitrophenylcaproate monitored by the appearance of p-nitro-phenoxide absorption by UV-VIS spectroscopy. These results confirm the effectiveness of the interactions between the hydro-phobic polymer chain and the hydrocarbon portion of the substrate, as it was previously mentioned, in accordance with the observations of Overberger et al (20).

Scheme 9.—Incorporation of o-Galactose into a /3-D-Glucopyranosyl Polymer Catalyzed by /3-D-Galactosyltransferase (EC 2.4.1.22), Followed by Photochemical Release of Lactose.

Some results of studies on the biosynthesis of two other Klebsiella capsular polysaccharides have also been reported. In the case of type 2 specific polysaccharide336 (27), incorporation of the D-mannosyl group from GDP-Man into glycosyl-lipids and the polymer, catalyzed by a cell-envelope... 

Dordick JS (1987) Production of phenolic polymers catalyzed by horseradish peroxidase in organic solvents. Proc Mater Biotechnol Symp 225-239... 

The hydrolysis rate of uncha d esters 7 in tlK presence of the polymer 14 was subtly smaller (ratio, 0.7—1.0) than those with NaOH, whereas, for the monoeth] esters of dicarboxylic adds 15, the polymer-catalyzed rates were greater than those with NaOH by factors of 2—5. In the presence of a similar, polymeric quaternary ammonium (PVBA-Cl) 16, the second-order rate constant of the alkali hydrolysis of... 

The importance of the anionic imidazole qiet is more apparent pdy-benzimidazole 2 (pK = 3.5, pKgj = 12.2) is emplt ed as catalyst (50). The value for polyvinylbenzimidazole-catalyzed solvtdy of PNPA 5 increased with increasing pH and was about four times greater than that for benzimidazcde-cata-lyzed solvolysis over the pH range of 4 to 10. i,n the polymer-catalyzed scdvol-ysis of NABS increased dmilarly with increa ng pH, whereas that for benziiiiid-... 

Table 1. Classification of Enzymes and in Vitro Production of Typical Polymers Catalyzed by Respective Enzymes...

As can be seen in Table 2, those polymers catalyzed very efficiently the process. As could be expected, catalytic efficiency decreases when the steric hindrance around the metal increases and when the number of Al-Cl bond decreases. Thus, for instance, catalyst 12b, where one Al-C1 bond had been replaced by one Al-O-Ar bond, showed to be about 200 times less efficient than the parent compound 12. As a matter of fact, supported catalysts were always far more... 

A polymer with repeating 6,6 -dibutyl-BINOL units that are linked to each other at C-5 and C-5 has been synthesized. The Ti-complex of the polymer catalyzes the addition of alkynylzinc species to aldehydes. ... 

Effect of Copper Stearate Concentration. As mentioned above, the thermal oxidation of the polymer catalyzed by copper compound (7.9 X 10 4M) proceeds very rapidly at the early stage and shows the leveling off of the oxygen uptake. Thus, the effect of the concentration of the copper stearate on the oxidation of the polymer was examined. The oxygen uptake curves of the thermal oxidation of the polymer in the presence of 3.2 X 10 5Af-7.9 X 10 3M copper stearate are shown in Figure 5. In this figure, the thermal oxidation of the neat polypropylene proceeds almost linearly. However, the copper stearate-catalyzed thermal oxidation of the polymer is affected remarkably by the copper concentration. In the presence of less than 3.2 X 10 3M copper stearate, the... 

Dibutylchlorostannyl)propyl-methacylate co-polymer catalyzes the homolytic cyclisation of the bromo-acetal BrCH2(BuO)CHOCH2CH=CHPr to 2-butoxy-4-butyl-tetrahydrofuran (24)The glycol (25) is oxidized by pyridinium chlorochro-mate to the cis-diol (26) stereospecifically. ... 

The kinetics of 2,4-dinitrophenyl-acetate hydrolysis catalyzed by polymers containing imidazole, carboxylic acid, oxidation groups and their complexes with surfactants, such as 1-cetylpyridinium chloride and cetylundecyldimethylammonium bromide, was determined by spectrophotometry [57]. Catalytic rate constants of the second-order-rate increase with a rise in the surfactant concentration until they reach a plateau at a polymer/surfactant ratio of 1 6. Anionic surfactant does not accelerate the polymer-catalyzed hydrolysis. The catalytic mechanism of a polymer/surfactant complex enables the penetration of the substrate into a pseudophase of a soluble complex. This leads to an increase of the ester concentration in the neighbourhood of a polymer imidazole fragment and accelerates the process. Such a pseudophase promotes the protonation of imidazole rings. 

The nucleophilic fragments of macroligands (particularly in styrene-A -vinylpyrrolidone copolymer) bring about a polymer-catalyzed decomposition of the metal carbonyl [53] via the scheme... 

Infinite ladders, which include solvent molecules, are shifted by a rung distance against each other and stacked like a stair in the direction of the b-axis. A two-dimensional square lattice of 34 is obtained from Cd and 4,4 -bipyridine (see Experiment 7-6, Section 7.7) [102,109]. Aromatic guest molecules can be incorporated, and the polymer catalyze the cyanosilylation of aldehydes [102]. The structure of [Ag(4,4 -bipyridine)N03] consists of linear silver-ligand chains which are crosslinked by an Ag-Ag interaction [110]. Infinite channels (2.3 x 0.6 nm) are formed which can reversibly incorporate PFe, Mo04 , BF4 and S04 ions. Pyrazine has also been used as a building block [111]. 

To confirm that the imprinted recognition site was indeed the reactive center, reactions were conducted in the presence of the imprinting template, 28, to determine its ability to inhibit the polymer-catalyzed reaction. A series of aldol reactions were conducted with increasing concentrations of 28. Figure 6 shows a Line weaver-Burk plot (a) and a Dixon plot (b) illustrating the increase in concentration of 28 leads to the decrease in efficiency of the MIP P-17 for the catalysis of chalcone formation. The concentration-dependent inhibition of chalcone production by 28 implies the presence of a specific reaction center in the polymer matrix. 

While polymerization reactions employing disilanes for the bis-silylation of unsaturated compounds have been known for some while [9], our system seems to be the first one to yield a high molecular weight polymer catalyzed by late transition metal complexes. 

Saponification of type (III) esters with poly(vinyl imidazole) (IV) as catalyst proceeds about 1000 times faster than saponification with imidazole (V) as catalyst. In addition, the polymer-catalyzed reaction is autocatalytic. The saponification rate increases with the length of the acyl residue (by a factor of 25 from w = 1 to w = 17). Obviously, increased methylene chain length leads to increasing intramolecular association of the polymer, which is acylated in an intermediate step of the reaction ... 

FIGURE 4.11 (A) Normalized fluorescence emission spectra of 1,4-diethynylbenzene (dotted line) and the PPB-containing composite materials of Cu-MAL and Cu-MSN catalysts (dashed and solid lines, respectively) after 56 h of polymerization, (B). C CPMAS spectra of (a) structurally aligned PPB polymer catalyzed by Cu-MSN, (b) PPB polymer synthesized with Cu-MAL, and (c) bulk PPB. The spectra were measured at room temperature, using 4680 scans, 10 s intervals, sample rotation rate of 5 kHz, contact time of 2 ms, CW H decoupling at 70 kHz, and sideband suppression (TOSS). (Figure modified from Reference 29.)... 

Nakano, M. Synthesis of novel crystaUine cyclic olefin polymer catalyzed by highly active nickel complexes. R D Review of Toyota CRDL 2000, 35, 82 Chem. Abstr. 2000,133, 238344. 

It is reasonable to ask if surfactant 4 by itself can act as micellar catalyst of autoxidation of 1-decanethiol. In a control experiment, 4 at the same concentration used in the polymer-catalyzed reactions was 0.5 times as active as latex MH-1. However, we have demonstrated that at least 95% of the surfactant in MH-1 is bound to particles, not free in solution, so the contribution of micellar catalysis to the reaction rates of Table 6 is negligible. 

Hu et al. [244] investigate the hydrolytic degradation of PLA/poly(e-aminocaproic acid) (Nylon 6) blends and found that hydrolytic degradation-formed lactic acid catalyzed and accelerated the hydrolytic degradation of Nylon 6. This can be applied to enhance the hydrolytic degradation of polycondensation-formed polymers catalyzed by hydro-nium ions. 

Take for example the intracellular degradation of PHB, a simplified mechanism can be observed in the scheme shown in the Fig. 5. This mechanism begins by the hydrolysis of chain polymer catalyzed by a i-PHB depolymerase leads to (/ )-3HB-CoA (1), after a 3HB dehydrogenase converts the (/ )-3HB-CoA to acetoacetyl-CoA (2) and a 3-ketoacyl-CoA thiolase converts the acetoacetyl-CoA to acetyl-CoA (3). After that, under aerobic conditions, the acetyl-CoA enters in the citric acid cycle and is oxidized to CO2 (Eggers and Steinbuchel 2013 Jendrossek and Handrick 2002 Lenz and Marchessault 2(X)5 Philip et al. 2007 Senior and Dawes 1973). 

Scheme 3.20 Process flow scheme for the combined continuous flow reactors for transition-metal-catalyzed heterogeneous hydrogenation and ion-exchange-polymer-catalyzed epimerization and the subsequent batch biotransformations.

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