Acidic Exchange Resin Research Articles

Study on Solid Acid Catalyzed Hydrolysis of Maltose and Related Polysaccharides

Within a study on combined hydrolysis and oxidation of starch toward D-gluconic acid the solid acid catalyzed hydrolysis of maltose as model compound was investigated. Acid zeolites and ion-exchange resins in the H*-form as well as amorphous silica-aluminas were used as the catalysts. The optimal conditions found for maltose were applied in the hydrolysis of amylose and starch. It is shown that the catalysis by zeolites and alumino-silicates involves homogeneous as well as heterogeneous catalysis.

Determination of equilibrium constants of strong acidic ion exchange resins by potentiometric titrations

A new method for the determination of ion exchange equilibrium constants is developed. A technique based in the application of potentiometric titrations is used in the study of non selective strong acidic resins. Potentiometric titrations are carried out without constant ionic strength, so a mathematical treatment is developed in order to take into account the estimation of the activity coefficients and the liquid junction potentials. The ion exchange thermodynamic equilibrium constants for two resins, Dowex CM-15 and Dowex C650, between the proton form and the alkaline metals at 25°C are given.

Isomerization of C-4 alkenes catalysed by macroporous ion exchange resin

The double bond isomerization of 1-butene, cis-2-butene and trans-2-butene catalysed by strong acid ion exchange resin was studied in the temperature range of 323–393 K and a wide range of pressure of alkenes (0.1–1 MPa) in the gas phase. A gradientless reactor with a shaking catalyst bed was used in the study. The rate constants of the reaction of isomerization as a function of temperature and partial pressure of alkenes are developed. At high pressures of alkenes the surface of resin was covered by products of polymerization, this reduced the activity of the catalyst.

Ion-Exchange Kinetics for the Removal of Potassium from Crude Polyols on Strong Acid Resins

Batch dynamics for the uptake of potassium from crude polyols on Amberlite 252, a strong acid ion-exchange resin, are obtained over a wide range of conditions. Experimental data have been analyzed using a homogeneous model with finite solution volume. An increase of diffusion coefficients with the resin weight used in the purification is observed. An asymptotic maximum value, approaching the value of the diffusion coefficient in bulk solution, is reached for high resin weights or low values of external concentration. The heterogeneous nature of the resin matrix and the large size of the diffusing molecule is proposed as an explanation of this behavior. The proposed purification procedure finds general applicability for other polyol types, being economically and technically feasible.

Synthesis of Novel Multifunctional Siloxane Oligomers Using Sol−Gel Techniques and Their Photoinitiated Cationic Polymerization

Employing modified sol−gel techniques, trialkoxysilanes bearing either epoxy or 1-propenyl ether functional groups can be condensed under well controlled conditions to yield a series of soluble multifunctional siloxane oligomers. The key to the success of this synthetic approach was the use of weakly acidic ion-exchange resins as catalysts. The novel multifunctional oligomers displayed exceptionally high reactivity in photoinitiated cationic polymerization using diaryliodonium salts as photoinitiators. Polymerization involved not only addition polymerization of the pendant epoxide or 1-propenyl ether groups but also acid-catalyzed hydrolysis and condensation of residual alkoxy groups along the siloxane backbone.

Pitfalls in the synthesis and biological evaluation of sialyl-Lewis X mimetics as potential selectin antagonists

The lower molecular weight analog 12 of sialyl Lewis X was prepared and effected equal binding affinity to E- and P-selectin compared to the parent tetrasaccharide. If 12 was prepared using acidic ion exchange resins, false positive test were produced, especially binding to P-selectin seemed to be considerably enhanced. Traces of polyanions released from the resins which are difficult to detect by routine analysis were identified to be highly potent selectin inhibitors, probably by their action on a non-carbohydrate binding site.

Potassium removal from water-methanol-polyol mixtures by ion exchange on Amberlite 252

Abstract Equilibrium isotherms for the uptake of potassium from polyol-water-methanol mixtures on Amberlite 252, a strong acid ion exchange resin, have been obtained in order to assess the possibility of using such a system to purify industrial polyether-polyols. The selectivity was very high. A two-step reaction scheme was proposed and equilibrium data were correlated by an equation derived according to the mass action law. Effective intraparticle diffusivities were obtained using a homogeneous model and the effects of the viscosity of the bulk solution and resin swelling on the exchange rate are discussed. A simple empirical equation correlating diffusivity with viscosity and resin swelling is suggested. Breakthrough curves were obtained under a wide range of conditions, being well correlated by the expression for breakthrough curves with rectangular isotherm. The proposed purification procedure is generally applicable to different polyol types, being economically and technically feasible.

Kinetics of the Heterogeneously Catalyzed Formation of tert-Amyl Ethyl Ether

In this work, the kinetics and equilibrium of the heterogeneously catalyzed liquid-phase formation of tert-amyl ethyl ether (TAEE) were studied. The catalyst used was a commercial sulfonic acid ion-exchange resin (Amberlyst 16W). The experiments were carried out in a continuous stirred-tank reactor, measuring stationary reaction rates. The measured reaction rates were fitted to three kinetic models; homogeneous, Eley−Rideal type, and Langmuir−Hinshelwood type. Of these, the Langmuir−Hinshelwood type model described the experimental results best. This model is based on single-site adsorption of every component, with the surface reaction being the rate-limiting step. The activation energies for the formation of tert-amyl ethyl ether from 2-methyl-1-butene were 90 and from 2-methyl-2-butene 108 kJ·mol-1. For the isomerization of 2-methyl-1-butene to 2-methyl-2-butene, an activation energy of 82 kJ·mol-1 was obtained.

Ion-exchange resins for solution phase parallel synthesis of chemical libraries

Described are various techniques that employ ion-exchange resins for the solution-phase synthesis of chemical libraries. We have found these resins to be useful as reagents and/or scavengers in a variety of reactions. Nine basic ion-exchange resins were evaluated for the catalysis and purification of an amide synthesized from an acid chloride. A number of the resins examined provided products in >95% purity. Acidic ion-exchange resins were also useful as scavengers in the synthesis of ureas. A demonstration of the utility of these resins for the preparation of amide, ester and urea libraries is also described.

Dimerization of α-methylstyrene over Nafion/silica composite catalysts

The dimerization of α-methylstyrene (AMS) 1 over highly dispersed strongly acidic ion exchange resins based on Nafion and entrapped in a porous silica matrix has been investigated in the continuous liquid phase. Over these new catalysts the dimerization rate is independent of the choice of solvent, which highlights the increased accessibility of the acid sites. Depending upon the reaction conditions different dimerization products are obtained. Complete conversion is achieved even at very high space velocities.

5563314 Process for the catalytic dehydrogenation of alkanes to alkenes with simultaneous combustion of hydrogen : Agaskar Pradyot A; Grasselli Robert K; Michaels James; Reischman P Thomas; Stern David L; Tsikoyiannis John G Hopewell, NJ, United States

The etherification of phenol and substituted phenols, such as o-chlorophenol, o-ethylphenol and guaiacol and α- and β-naphthols with isobutylene and isoamylene was studied. The etherification was carried out in the presence of an acidic ion exchange resin, Amberlyst 15, as a catalyst and in the temperature range of 5 to 30°C. The relative rates of etherification of phenol / o-chlorophenol, o-ethylphenol / guaiacol and α-naphthol / β-naphthol were measured. A novel separation strategy, based on selectived etherification and subsequent cracking of tert-buryl / tert-amyl ethers, was successfully applied for the close boiling phenols and naphthols. The purification of β-naphthol containing α-naphthol impurity through the selective acid catalysed C-alkylation of α-naphthol with isobutylene and isoamylene was also found to be succesful.

5564159 Closed-loop multistage system for cleaning printed circuit boards : Treiber John H Huntington Beach, CA, United States assigned to The John Treiber Company

The influence of catalyst, solvent and temperature on the etherification of glycerol and ethylene glycol with isobutylene in the liquid phase catalysed by strong acid ion-exchange resins of Amberlyst type (Amberlyst 15 and 35), p-toluenesulfonic acid and by two large-pore zeolites H-Y and H-Beta was studied. Reactions were carried out in the temperature range from 50 to 90 °C at autogenous pressure in solvent (dioxane, dimethyl sulfoxide and sulfolane). The basic kinetic parameters for complex of 11 equilibrium reactions for glycerol and 5 equilibrium reactions for ethylene glycol were estimated. The highest conversion of glycerol was achieved on H-Beta, but on this catalyst the formation of tri-tert-butyl glycerol was sterically hindered. The highest amount of di- and tri-ethers was formed over Amberlyst 35. Over H-Y the reaction was slower due to its lower acidity, and final concentration of di- and tri-ethers was not achieved in monitored reaction time. p-Toluenesulfonic acid provides satisfactory results only when sulfolane was used as a solvent. The solvent plays an essential role because it can affect the investigated etherification reaction with its polarity and homogenization of reaction mixture. The concentration of glycerol and ethylene glycol higher ethers in end product can decrease as temperature increases showing that the side reaction of isobutylene dimerisation is more sensitive to temperature.

ChemInform Abstract: Convenient Selective Monoesterification of α,ω‐ Dicarboxylic Acids Catalyzed by Ion‐Exchange Resins.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Convenient selective monoesterification of α, ω-dicarboxylic acids catalyzed by ion-exchange resins

Symmetric dicarboxylic acids, ranging from pentanedioic acid to tetradecanedioic acid, gave selectively the corresponding monoesters in high yields in the transesterification catalyzed by strongly acidic ion-exchange resins in ester/octane mixtures.

The synthesis of tertiary amyl methyl ether (TAME): Microkinetics of the reactions

The microkinetics of the liquid-phase synthesis of tertiary amyl methyl ether (TAME) from methanol and a mixture of isoamylenes, namely 2-methyl-1-butene and 2-methyl-2-butene, using a macroporous sulphonic acid ion exchange resin as catalyst (Lewatit SPC 118) was determined in a continuous-flow recycle reactor in the temperature range 323–343 K at 1.6 MPa. The reaction proceeds within the gel phase of the microspheres overlapped by a multiple sorption equilibrium between components in the macropore liquid and the gel phase. A kinetic model was developed using the microkinetic data from experiments, where Langmuir sorption isotherms in liquid-phase activities from a modified UNIFAC method were assumed to describe the sorption behaviour of the components. The rate-controlling step, the chemical reaction of sorbed molecules, was formulated according to the homogeneous catalysis as first order in all species. The forward reaction is proportional to the activity ratio of isoamylenes to methanol and the activation energy was determined to be 89.5 kJ/mol.

Esterification of formic acid, acrylic acid and methacrylic acid with cyclohexene in batch and distillation column reactors: ion-exchange resins as catalysts

Esterification of formic acid, acrylic acid and methacrylic acid with cyclohexene was carried out in the presence of cation-exchange resins as catalysts. Effect of various parameters, e.g. speed of agitation, catalyst particle size, catalyst loading, types of catalyst, temperature, mole ratio of the reactants, was studied to optimise the reaction conditions. The reaction of formic acid, with different concentrations in aqueous solutions, with cyclohexene was studied. Experiments were carried out in the presence of homogeneous catalyst, p-toluene sulphonic acid ( p-TSA), to compare results with the heterogeneous catalyst. A comparison of anhydrous esterification between acrylic acid and that of methacrylic acid with cyclohexene has been reported. The conversion of formic acid in aqueous solutions to cyclohexyl formate, by reaction with cyclohexene, in a distillation column reactor (DCR), packed with an acidic ion-exchange resin catalyst was studied; the effect of variables such as feed flow rate, molar ratio of reactants, amount of catalyst in the reboiler, concentration of formic acid, location of the feed point, etc., was studied. A comparison between the rate of esterification of formic acid with cyclohexene in batch mode and in distillation column reactor has been made. An attempt was also made for the selective esterification of formic acid with cyclohexene from a mixture of formic acid and acetic acid in a DCR.

Solid acid (superacid) catalyzed regioselective adamantylation of substituted benzenes

Adamantylation of substituted benzenes with 1-bromo-adamantane was catalyzed by solid acids including acidic ion exchange and ionomer resins, HY zeolite, sulfated zirconia and supported superacids on HY zeolite and SiO2. Adamantylation generally takes place in excellent yield giving predominantly para products without formation of byproducts. The reactions did not require the usual workup of Friedel-Crafts reactions as catalysts were simply filtered of. Cross-linked polystyrene resin sulfonic acid (Amberlyst) was found particularly suitable as besides its high catalytic activity, high regioselectivity was observed with almost exclusive formation ofp-adamantylated benzenes. AMI, PM3 and MNDO semiempirical calculations of heats of formation showed that of all regioisomers, the para isomer is the most stable. The temperature dependence of adamantylation was also investigated allowing the optimization ofp-substituted product in high yield and excellent selectivity. Lack of isomerization of 1-p-tolyla-damantane using solid (Amberlyst, Nafion-H) and liquid acids (neat and modified trifluoromethanesulfonic acid) indicates absence of product isomerization, while the intramolecular rearrangement of the intermediate arenium complex is still possible.

Synthesis of long chain alkyl and chloroalkyl esters of perfluorosalicylic acid, new potential high temperature antifriction additives for advanced motor oils

Long chain alkyl and chloroalkyl esters of perfluorosalicyclic acid, which are potential antifriction additives for lubricating oil or fuel, are prepared by treating equimolar amounts of perfluorinated salicylic acid and a long chain alkyl alcohol in benzene in the presence of a strongly acidic ionic exchange resin.

Synthesis and Ion-Complexing Properties of a Novel Polymer-Supported Reagent with Diphosphonate Ligands

A new chelating resin with diphosphonate groups has been synthesized from the tetraethyl ester of 1,1-vinylidenediphosphonic acid. Comonomers such as acrylonitrile allow the sterically hindered monomer to be incorporated into the polymer network. A copolymer was prepared by suspension polymerization in high yield with diphosphonate, acrylonitrile, and styrene in the monomer solution at a 4.5:1:3.1 weight ratio and 5 wt % divinylbenzene as the cross-link agent. Bifunctionality enhances metal ion complexation kinetics. The diphosphonate ligands are selective chelators, while sulfonic acid ligands covalently bound to the phenyl groups enhance the accessibility of metal ions in the polymer matrix. The complexing ability of the polymer is studied with Eu(III) as the target ion in 0.04−4.0 N HNO3 solutions in both the presence and absence of 0.40 N NaNO3. A sulfonic acid ion exchange resin complexes 14.3% Eu(III) while the diphosphonate-based polymer complexes 96.5% from a 1 N HNO3/0.4 N NaNO3 solution.

Synthesis of Methyl tert-Butyl Ether Catalyzed by Acidic Ion-Exchange Resins. Influence of the Proton Activity

The catalytic activity of various strong acid ion-exchange resins on the synthesis of methyl tert-butyl ether (MtBE) from methanol and isobutene has been investigated. Relative to Amberlyst 15, Kastel CS 381 and Amberlyst CSP have similar rate constants, whereas Duolite ES 276 and Amberlyst XE 307 have significantly higher and Duolite C26 and Duolite C16P substantially lower rate constants. All resins show a great decrease in catalytic activity if part of the protons is exchanged by sodium ions. At 10% proton capacity the rate constants per equivalent acid are reduced by a factor of 9 (for Amberlyst XE 307 and Kastel CS 381) to more than a factor 20 for Amberlyst 15 and Duolite ES 276, resulting in 100-200 times lower MtBE production rates. Depending on the catalyst applied, mass transfer limitations start to occur between 50 and 80 degrees C. Values of the effective diffusion coefficient of isobutene varied between 0.4 x 10(-9) and 4.1 x 10(-9) m(2) s(-1) at 80 degrees C.