Reactive Polymers最新文献

The catalytic activity of gel and macroreticular ion-exchange resins (Lewatit and Amberlyst-15) was evaluated for the reaction of benzene with benzyl alcohol and benzyl chloride at 80°C in the liquid phase. With benzyl chloride, the monobenzylation product, diphenylmethane, was obtained in low yield, both with the gel and the macroreticular resins. Better results were obtained with benzyl alcohol as benzylation agent and the most active resin was Amberlyst-15. The benzylation of toluene and anisole with benzyl alcohol, catalyzed by Amberlyst-15, was also evaluated, the conversion of benzyl alcohol being proportional to the concentration of acid sites in the resin. Monobenzylation to benzyl toluene or benzyl anisole is the main reaction and the selectivity was usually found to be higher than 80%, when a toluene/alcohol or anisole/alcohol molar ratio of 10 is used. Secondary reactions to dibenzyl toluenes, dibenzyl anisole and benzyl ether occur to a varying extent, depending on the substrate ratios. In all cases, predominance of ortho/para isomers was observed.

The preparation and properties of 8 N-phenylsubstituted polyacrylohydroxamic acids as ion exchange resins are described. These were synthesized by the reaction of polyacryloyl chloride with N-aryl hydroxylamines in etherial medium. The chelating properties of the resins were determined and compared with each other. The extraction of divalent metal ions as a function of pH and kinetics of their sorption were studied. The chromatographic separation of metal ions from the mixtures is also described.

We have found that amino-functional polymers absorb and readily bind nitrogen oxides (NO_x) namely NO₂ and NO. Our previous results showed that the reaction of NO_x with polymer-grafted primary and secondary amines yielded stable products, subsequently identified as nitrite and nitrosamine derivatives, which cannot be thermally degraded to regenerate the original amino-polymer and thereby release the absorbed NO_x. Consequently, we have prepared and evaluated polymers carrying pendant sterically hindered tertiary amines with the proper electron donor-acceptor properties to bind specifically NO_x. The results of thermogravimetric analysis experiments showed that dipropylamine-functional polymers absorb and bind NO₂ effectively and reversibly while they remain almost/completely inert when exposed to relatively weaker acid gases such as SO₂ or CO₂.

Resin (RPPBD) prepared by Friedel-Craft's polycondensation of 2,4-dihydroxypropiophenone with 1,4-butane diol in the presence of polyphosphoric acid catalyst proved to be a selective ion-exchange resin and indicates coordination tendency for some metal ions. The resin was characterized by elemental analysis, IR spectra, viscosity study and its number average molecular mass ($\text{M}{}_{\mathrm{<mtext>n</mtext>}}$) was determined by non-aqueous titration and found to be 2475 g/mol. Chelation ion-exchange properties of this resin have also been studied employing batch equilibration method. It was employed to study selectivity of metal ion uptake over a wide ph range and in media of various ionic strength. The overall rate of metal uptake follows the order: UO₂²⁺ > Fe²⁺ > Cu²⁺ > Ni²⁺

Immobilized catalysts were prepared from silica gel and montmorillonite functionalized by silane coupling reagents. Complexes with metal ions were easily formed. The dioxygen oxidation of hydrocarbon using the immobilized catalyst was investigated. Cyclohexanol (mainly) and some cyclohexanone were produced by the oxidation of cyclohexane at ordinary temperature, under atmospheric pressure. Dioxygen oxidation of the non-activated β-position of the ethyl group in ethylbenzene was observed in the presence of cobalt ion-immobilized montmorillonite catalyst in the presence of lithium ion.

In our ongoing research program on the development of new chelating hollow fibers based on sulfochlorinated polyethylene (PESCI), several types of chelating materials containing amine ligands were prepared by reaction of PESCI with diamines. The preparation procedure was studied carefully in the light of a possible hydrolysis reaction that can occur during the interaction of the diamine with PESCI. It was found that the reaction of PESCI with aliphatic amines differed from that with heterocyclic amines. Aminopyridines having the amine group substituted in the pyridine ring formed a sulfamide bond, which was rather unstable and could be hydrolyzed and destroyed during the reaction. However, when the NH₂ group was bound to the pyridine via an aliphatic bridge, pyridine-containing chelating hollow fibers were obtained.

A new process has been developed for gel-coating a weak-base resin polyethyleneimine (PEI) as a thin layer on high surface area silica using preloaded Cu(II) as the host ion on silica and glutaraldehyde as the cross-linking agent, followed by removal of the host ion by leaching with acid. The >NCH(OH) group introduced by the reaction with glutaraldehyde is found to enhance both U and Fe sorption, the effect, however, being relatively more pronounced on the latter. An $\text{O}\text{N}$ mole ratio ∼0.70 of the gel-coated PEI resin is found to be optimum for U sorption. In U sorption from dilute (0.1–0.4 mM) aqueous solutions of UO₂SO₄ at pH 4–5, the gel-coated resin exhibits several times higher capacity than a conventional bead-form resin Dowex-1X8. However, the capacity of the resin-coated silica sorbent, containing a large percentage of low-capacity silica, is only comparable to that of the bead-form Dowex resin at low solution concentrations. The gel-coated resin also exhibits a significantly faster rate of attainment of equilibrium sorption as compared to the bead-form Dowex resin, the sorption kinetics being diffusion-controlled with a high value of 8.4 × 10⁻⁶ cm²/s for the product of distribution coefficient and effective diffusivity. The stripping of the sorbed U from the gel-coated sorbent with 2 N H₂SO₄ is nearly instantaneous.

Poly[ethylene-g-(vinylbenzyl chloride)] (1) film was prepared and used as an intermediate for the synthesis of polymer supported bis(phosphonic acid) derivatives. (1) was synthesized by preirradiation grafting of vinylbenzyl chloride (VBC) on polyethylene film. A reaction time of 29 h gave (1) with a chlorine capacity of 4.7 mmol Cl/g. As shown by energy dispersive X-ray analysis, the depth of the graft modification can be varied from surface to bulk modification by controlling the reaction time. The gel content of the film was found to increase with increased extent of grafting. A 28% VBC grafted film was found to have a gel content of 91%. The swelling of the Poly[ethylene-g-(vinylbenzyl chloride)] (1) film in toluene or THF was rapid A 145% VBC grafted film swells 260 area % within 2 min in refluxing toluene. Tetraisopropyl methylene-bisphosphonate (2) or tetraethyl ethane-1,1-bisphosphonate (3) were reacted with NaH and used for nucleophilic substitution of chlorine in the poly[ethylene-g-(vinylbenzyl chloride)] film. Forty-six percent of the chlorine groups were substituted within 24 h using the sodium salt of tetraisopropyl methylenebisphosphonate (2) in a 10-fold excess in refluxing toluene. Under the same reaction conditions, using the sodium salt of tetraethyl ethane-1,1-bisphosphonate (3) gave 50% substitution. Energy dispersive X-ray analysis showed that the substitution reaction proceeds throughout the film at the same rate, which implies that the reaction is not mass-transfer controlled. Hydrolysis of the polymer supported bisphosphonate in hydrochloric acid to yield the bis(phosphonic acid) form gave a film which swells 60 area % in water at room temperature and 100 area % at 100°C.

A convenient method to prepare spherical microparticulate composite adsorbents is described. Molecularly imprinted crosslinked methacrylate polymers were copolymerized with preformed microparticulate support particles of trimethylolpropane trimethacrylate (TRIM) containing residual double bonds. The resulting composite adsorbent could be packed in HPLC columns after just a simple washing procedure and was used for efficient chiral separation of amino acid derivatives. The pore system of the TRIM-particles could be filled with large amounts of functional polymer. The enantioselectivity for the print molecule Boc-L-Phe-OH was in the same range as that obtained by traditional bulk phase molecular imprinting, while the performance in HPLC was improved, both in terms of efficiency and pressure stability. The effect of various degrees of crosslinking and of monomer concentration on polymer characteristics, such as porosity and specific surface area, and its impact on the structure of the final polymer is discussed as well as the chromatographic performance of the resulting matrices.

Sorption experiments with a variety of organic compounds dissolved or suspended in water and a new hypercrosslinked polystyrene-type sorption material ‘Styrosorb’ (‘Macronet-Hypersol’) showed superiority of the latter to other chemically related adsorbents