Magnetic weak-base ion exchangers with capacities of up to 6.2 meq/g were made by the reaction of liquid (branched) polyethyleneimine (PEI), (of number-average molecular weight 600–1800), with particles of PVC or diaminohexane-crosslinked polyepichlorohydrin containing a magnetic filler. The PEI distributed itself throughout the polyvinylchloride (PVC) particles, crosslinking them. Polyamines of higher molecular weight (in solution) react at the surface of the magnetic particles to form low-capacity ion exchangers having a core-shell structure. Linear polyepichlorohydrin (PECH) can be coupled to magnetic crosslinked PECH particles by reaction with the amino groups of the crosslinks. Polyethyleneimine coupled to magnetic particles can be carboxymethylated with chloroacetate, but resists quaternization. Alternatively, magnetic resins can be made by the mutual crosslinking of PEI and PVC or PECH in quasi-solution, and subsequently derivatized either by carboxymethylation or partial quaternization of amino groups or by displacement of residual reactive chlorines by thiols, for example. Magnetic polyamine resins or their derivatives adsorb Cu2+, Ni2+, Fe3+, Zn2+, Cd2+ and Hg2+ ions from aqueous solution.
A crosslinked chelating ion exchange resin containing two iminodiacetic acid (IDA) groups per s-triazine ring was readily synthesized in a batch reaction from IDA, cyanuric chloride (CC) and poly(p-aminostyrene) (PAS) or polyethyleneimine (PEI). A two-step reaction involving the reaction between IDA and CC as the first step and that between the intermediate product and PAS as the second step gave best results with respect to resin yield and metal uptake. Other reaction procedures and some attempts to prepare a porous resin gave lower yield and metal uptakes. Interfacial condensation was used to synthesize PEI-containing resins (PEIC) and gave products with higher metal uptake but in lower yield. Yield, properties, and practical usefulness of the products were compared with those of other resins.
Generally, aromatic compounds cannot be directly intercalated into a zirconium phosphate-type matrix. Various methods were used to achieve this: (a) intercalation into α-zirconium phosphate via its ethanol complex; (b) intercalation into α-zirconium phosphate and its derivatives after defoliation of their layered structure.
Merrifield resin was reacted with tetrachlorohydroquinone to give a polymeric monobenzyl ether of tetrachlorohydroquinone. The esters of this functionalised polymer, like the esters of other polyhalogenated phenols, act as polymeric active esters. These have been used for transacylation of amines, where acylated products were obtained in high yields in a clean reaction. Synthesis of some peptides has also been achieved using the polymeric active esters of N-protected amino acids.
When poly(chlorotrifluoroethylene) is reacted with the dianion of 3-mercaptopropionic acid, a substituted polymer with pendant carboxylic acid functionality is produced. Further reactions, such as esterification and reduction to the alcohol, can be performed on the acid groups. Chemical transformation of the alcohol produced the corresponding tosylate, halide, trimethylsiloxy, and trichloroacetate derivatives. By increasing the variety of functionality available, the possible utilizations of these polymers as reactive polymers and as solid phases in chromatography are thus increased.
Polymer-immobilized metal complexes were prepared by sorption of FeCl3 and chromium compounds on latex particles of crosslinked 4-vinylpyridine-poly(ethylene oxide) copolymers. Catalytic activity and selectivity of these complexes in the esterification reaction of methacrylic acid and ethylene oxide were studied. They provide high degrees of conversion (96–100%) with minor formation of by-products. On repeated use the catalytic activity slightly decreases.
The catalytic activity of different polymers containing axime groups has been tested in the hydrolysis of structurally different esters of p-nitrophenol. The mechanism of hydrolysis, supported by indirect kinetic evidence, seems not to involve a pre-equilibrium with a polymer-ester complex. The reaction was investigated under pseudo-first-order conditions with an excess of oxime polymer. The values of the second-order catalytic rate coefficients suggest a reaction rate mainly controlled by steric effects and hydrophobic interaction between the ester hydrocarbon residue and the macromolecular chain.
Polymer-bound crown ethers were obtained by Mannich reaction of benzocrown ethers with amino polymers, polycondensation of dibenzo-18-crown-6 with acyl dichlorides, and polycondensation of benzocrown ethers with formaldehyde and aromatic compounds. Complexation reactions with potassium thiocyanate or picrate as well as with perchloric acid were used for crown ether group determination. The reaction kinetics of polymer-bound crown ethers with potassium iodide were studied.
1-Allyl-2-methylene succinate (α-MAI) was synthesized by partial hydrolysis of diallyl itaconate (DAI) in the presence of hydrogen chloride. The three allyl itaconates (DAI, α-MAI and β-MAI) were polymerized or copolymerized separately with methyl acrylate (MA) in suspension, producing beads with varying resistance to hydrolysis. The beads containing DAI were hydrolyzed hardly at all. The beads made from 4-allyl-2-methylene succinate (β-MAI) were hydrolyzed relatively easily. Those made from α-MAI proved rather stable to alkaline hydrolysis; under general conditions for regenerating a weak-acid ion exchange resin they demonstrated strong stability against hydrolysis. The weak-acid ion exchange resin prepared from MA, DAI, α-MAI and a small amount of DVB had a high exchange capacity but did not produce sticky beads. α-MAI and DAI can be used as crosslinking agents to produce macroporous adsorbents of intermediate polarity.
The exchange of the Na+ ions in zeolite X, and the parent and dealuminated forms of zeolite Y by Cs+, NH+4, Ca2+ and La3+ have been studied at 25, 65 and 85°C. The selectivities of the ongoing ions have been determined. The NaCs exchange changes from an exothermic to an endothermic reaction on increasing the Si/Al ratio. Interesting differences in the maximum exchange of Na+ by the above four ions as the Si/Al ratio increases has been found. These results tend to indicate that 30 Na+ ions per unit cell are sited in the sodalite cages and hexagonal prisms of hydrated zeolite X.
Several porphyrins and metalloporphyrins have been reversibly and covalently attached to a functionalized insoluble polystyrene matrix, α-[(4-bromomethyl-3-nitrobenzamido)benzyl]-poly(styrene-co-divinylbenzene). Insertion and removal of Zn(II) on the supported species has been successfully achieved. The products have been identified by alkaline detachment as well as spectroscopically.
The behaviour of some weak-base resins in gold cyanide solutions was unexpected under certain conditions. At pH values where the resins should have been in their free-base form and not functioning as anion exchangers, they sorbed gold cyanide. Titrations of various resins were carried out in the presence of gold cyanide and in its absence. The effect of high concentrations of sodium hydroxide on the extraction of metal cyanides by certain resins was investigated. From the results of the experiments it was proposed that in addition to the conventional mechanism of ion-pair formation with the protonated functional group, metal cyanides could be loaded by another mechanism which probably involves sorption of an ion pair formed between the cyanide anion and a sodium cation.
Arsenate and arsenite are selectively removed by ligand exchange sorption on iminodiacetic chelating resin Chelex 100 used in ferric ion form, the saturation sorption capacities being 45 and 70 mg As / g wet resin with respect to As(V) and As(III) anions, respectively. The liquid sorption of As(V) anions is maximum at pH ∼ 2 and that of As(III) anions at pH ∼ 10. Monovalent anionic species H2AsO−3 are mostly involved in ligand sorption on Chelex (Fe3+), and on average approximately one and two anionic species of As(V) and As(III), respectively, are coordinated to each resin-bound Fe3+ ion at saturation. The sorbed anionic species are readily stripped with dilute sodium hydroxide into a concentrated form for recovery. An enrichment of more than 40-fold relative to influent concentration (< 100 ppm As) is obtained in ligand exchange column operation for arsenate, as compared to less than 20-fold enrichment for arsenite. Reactivation of the stripped resin is performed in one step by treatment with a mildly acidic solution of ferric chloride (pH ∼ 2), which reconverts the resin to the chelated-Fe3+ form. The regenerated ligand exchanger exhibits a higher sorption capacity due to additional ion-exchange sorption on the accumulated ferric hydroxide gel. The ligand sorption capacity of the polymer-chelated Fe3+ ion is, however, several-fold higher than the anion exchange capacity of the ferric hydroxide gel, with respect to both As(V) and As(III) anions.
The effect of the degree of loading, α, of polystyrene with DMAP ligands on the catalytic activity of “polystyrene-bound DMAP”-copper catalysts in the oxidative coupling of 2,6-dimethylphenol was studied. The intrinsic activity increases upon enhancing α from 0.096 to 0.23. This increase proved to be mainly brought about by an increasing “strain” in the polymeric catalyst. An additional accelerating effect is the increase of the amount of catalytically active mononuclear complexes CuL4(OH)Cl with increasing α up to α = 0.134. This is due to a stronger polydentate effect for higher α because of the higher local ligand concentration within the polymer coils, which can be regarded as separate micro-reactors. For α > 0.23 the interligand distance becomes too short to link adjacent ligands to the same copper ion. Consequently, some ligands have to be skipped in favour of next ones, the strain is somewhat released and the intrinsic activity slightly decreases. For α⩾ 0.096 the phenol oxidation step proved to be rate limiting. However, for very low chain loadings, e.g. α = 0.044, the local concentration of mononuclear copper complexes within the coils becomes too low and the dimerization which is needed for the Cu(I) reoxidation becomes rate determining. The catalytic specificity proved to be independent of α under our reaction conditions.
There is a general opinion that the most important factor influencing water quality is incomplete separation of the resins before the regeneration. We have confirmed that the effluent quality proportionally decreases with increasing cross-contanimation. However, not all types and not even all resins of the same type behave in the same manner. The effect of regenerant level, rinsing and mixing is less important. The results presented show that the influence of improper separation techniques (cross-contamination) can be diminished by the proper choice of resin combination for a given separation procedure. The experimental work led to the development of a new system of ultrapure water production. This method allows excellent water quality to be achieved at low regenerant levels.
Immobilization of microsomal fractions, proteolytic enzymes and urease on polyethylene-grafted poly(acrylic acid), poly(allyl alcohol) and poly(allylamine) was investigated. Immobilization of microsomal fractions on polyethylene-grafted poly(allyl alcohol) and poly(acrylic acid) preserved 108 and 31.5% of aniline hydroxylase activity and 125 and 109% of N,N-dimethylaniline demethylase activity, respectively. An increased pH, temperature, and storage stability of the immobilized microsomes was observed. Column operation was performed as well. Positive results were also obtained in the immobilization of urease and Bacillus mesentericus protease.
A critical overview is presented on the use of anion-exchange-type resins, conventional and modified, including also polymeric crown ethers and related moieties,as catalysts in organic synthesis. The analysis of the available material has been organized to highlight the effects of specific structural and physical parameters of the polymer matrix, such as loading extent and topology of active sites, degree of crosslinking, porosity, surface area and particle size. Semi-quantitative evaluation of the above parameters has been carried out by comparing the specific activity and selectivity of polymer catalysts with their low molar mass analogues in standard nucleophilic substitution, addition and elimination reactions. Examples have been included of polymer catalysts that are more active and sometimes more selective than the corresponding low molecular weightanalogues. Cooperative effects of polymer-constrained structural units play a key role in determining the reported behaviour.
The rapid ion-chromatographic separation of calcium, magnesium and strontium ions was investigated in suppressed and non-suppressed ion-chromatography systems. The effects of eluent composition on the distribution ratios of alkaline earth ions were studied for both methods. Linear plots of log distribution coefficient vs. log eluent concentration were obtained in all cases. There is good agreement between the theoritically predicted and the observed slopes of these functions. The influence of eluent composition on the peak resolution was also examined and the optimum eluent composition was selected. The separation characteristics (resolution, speed of separation) and sensitivity of the two methods are compared.
Crosslinked polystyrene resins containing pendant benzyl acrylate or chiral acrylates derived from R-(−)-1,3-butanedoil reacted with 1,3-butadiene or 2,3-dimethyl-1,3-butadiene in the presence of the Lewis acid catalysts TiCl4, TiCl3(OiPr), or TiCl2(OiPr)2 to yield Diels-Alder adducts. Cleavage of the adducts gave racemic or optically active 3-cyclohexen-1-ylmethanol and 3,4-dimethyl-3-cyclohexen-1-ylmethanol. The polymerbound Diels-Alder reactions were compared with their analogous reactions in solution. In reactions leading to optically active products the enantiomeric excesses on the polymer were at least as high as those performed in solution.
The relationship between silica fouling of a strong-base anion exchange resin and polymerization of silicic acid or size of polysilicic acid molecules was studied. The amount of silica adsorbed by the resin increases with the concentration of low-molecular weight polysilicic acids. The SiO2 content of the resin reaches a maximum at an aggregation number of 3.3.
