Macroreticular p-(omega-sulfonic-perfluoroalkylated) polystyrene ion-exchange resins: a new type of selective solid acid catalyst

Macroreticular p-(omega-sulfonic-perfluoroalkylated) polystyrene (FPS) cation-exchange resins have been synthesized by sequential p-perfluoroalkylation of macroreticular polystyrene (PS) with omega-fluorosulfonylperfluorodiacyl peroxide 2, hydrolysis and acidification; the fluorinated mesoporous resins exhibited higher activity and selectivity than commercial Amberlyst 36 and Nafion NR50 in the cyclization of pseudoionone.     

Heterogeneous catalysis using a nanostructured solid acid resin based on lyotropic liquid crystals

The catalytic reactivity and selectivity of the first example of a nanostructured solid acid resin (1) are described. This new type of solid acid catalyst is formed by the self-assembly and copolymerization of two acidic lyotropic liquid crystals (LLCs), affording a columnar hexagonal polymer network with monodisperse nanochannels lined with sulfonic acid groups. The performance of this material as a heterogeneous catalyst was compared against that of two commercially available, amorphous sulfonic acid resins: Amberlyst-15 and Nafion NR50. Using the acid-catalyzed esterification of benzyl alcohol with 1-hexanoic acid in dry toluene as a test reaction, it was found that resin 1 displayed only slightly lower overall reactivity as compared to Amberlyst-15 and Nafion NR50 but more than an order of magnitude higher selectivity for the desired ester product over dibenzyl ether side-product. Control experiments revealed that the higher product selectivity is not due to differences in relative acidity between the nanostructured acid resin and the two amorphous resins. Instead, it appears that a large component of the enhanced selectivity is due to the regular nanostructure present in the LLC resin, which affords a much more uniform local acid microenvironment for reactions to occur. Resin 1 can also be recycled with almost complete recovery of catalytic activity and selectivity, and with essentially no leaching of reactive groups into the solution phase.     

以强酸性阳离子交换树脂为催化剂合成14-氧杂二环[10,3,0]十五碳烯-2

以三种类型的强酸性阳离子交换树脂(聚苯乙烯磺酸树脂、酚醛磺酸树脂和全氟磺酸树脂)为催化剂进行环十二碳-烯的普林斯反应,合成了14-氧杂二环[10,3,0]十五碳烯-2.考察了该三种树脂的催化性能,并与苯磺酸和对甲苯磺酸的催化性能作了比较.考察了孔径、粒度及反应条件(温度、时间、催化剂用量等)对聚苯乙烯磺酸树脂催化性能的影响.实验结果表明:全氟磺酸树脂和交联大孔聚苯乙烯磺酸树脂(交联度10％,孔径3.9×10²Å,比表面积20m²/g)具有良好的催化性能.     

The Polymerization of 1,3-Dioxolane Catalyzed by Ion Exchange Resin (Polystyrene Sulfonic Acid)

Polystyrene sulfonic acid resin (Amberlyst 15) was found to initiate the cationic polymerization of 1,3-dioxolane easily in bulk at 0 to 50° C, and polymers with a reduced viscosity of 0.1 were obtained. However, this resin showed only low initiator activity for the polymerizations of 2-methyl-1, 3-dioxolane and trioxane.     

Cationic oligomerization of styrene by solid acids. I. Catalysis by poly(styrenesulfonic acid) resin

Cationic oligomerizations of styrene by a solid acid [poly(styrenesulfonic acid) resin, Amberlyst 15] and by the corresponding soluble catalyst (p-toluenesulfonic acid) were compared with respect to their reactivity and the molecular weight distribution of products. The feature of Amberlyst 15 as oligomerization catalyst, in addition to its easy separation from products, was found to be was follows: The activity of Amberlyst 15 was 10 times larger than that of p-toluenesulfonic acid in benzene, although catalyst deactivation at high conversions was observed for Amberlyst 15 at high monomer concentrations. Styrene trimer and tetramer were dominantly produced by Amberlyst 15 at low monomer concentrations, whereas a linear dimer was obtained in 85% yield with p-toluenesulfonic acid. Characteristically, solvent polarity had almost no effect on the reaction rate and product composition in the Amberlyst 15-catalyzed oligomerization. These facts were discussed in relation to differences between the heterogeneous and homogeneous catalyses.     

氧化硅组装纳米Nafion酸催化合成α-生育酚

以自制的Nafion溶液、正硅酸乙酯为原料，通过溶胶-凝胶方法，将Nafion纳 米颗粒分散组装到多孔性SiO_2中，制得高比表面积纳米复合物Nafion/SiO_2固体 酸催化剂大大提高了Nafion所含酸性中心的暴露率和可接近程度。在非极性溶剂正 庚烷和甲苯中，13% Nafion/SiO_2固体酸对α-生育酚的合成具有很好的选择催化 作用。相对于致密性Nafion树脂而言，13% Nafion/SiO_2纳米复合物单位酸中惊扰 催化活性增加了10倍。     

Kinetics,mass transfer,and thermodynamic and statistical modeling study for esterification of valeric acid with n‐butanol: Homogeneous and heterogeneous catalysis

The esterification of valeric acid with n‐butanol was studied with homogeneous and heterogeneous catalysts. The activity and performance of homogeneous p‐toluenesulfonic acid and heterogeneous cation exchange resin catalysts Amberlyst 36, Indion 190, and Amberlite IRC‐50 were evaluated. The pseudo‐homogeneous kinetic model was used to investigate the kinetic parameters of homogeneous‐ and heterogeneous‐catalyzed esterification. The UNIFAC (universal functional activity coefficient) approach was used to study the nonideality of the esterification reaction. The reaction was statistically modeled and optimized by the application of response surface methodology. The effects of independent variables such as reaction temperature, initial molar ratio, and catalyst loading on the conversion of valeric acid were investigated. The optimized conditions for the esterification reaction catalyzed by Amberlyst‐36 were found as temperature 360.4 K, initial molar ratio 3.8, and catalyst loading 6.7 wt%. The predicted conversion (89%) at these optimized conditions is in good agreement with the experimental conversion (87.3 ± 1.6%).     

新型固体酸催化剂Nafion/SiO2的制备与表征

以正硅酸乙酯为硅源,通过原位溶胶-凝胶技术,制得一类由中孔孔道氧化硅组装的纳米Nafion固体酸催化剂Nafion/SiO2,大大增加了Nafion^(R)NR50酸性中心的暴露量,提高了活性中心的可接近程度。BET,FTIR,TG,SEM和EDX分析表明,NR50的纳米颗粒负载在多孔性SiO2中呈现分布均匀;NH3-TPD分析结果表明,固体酸催化剂Nafion/SiO2具有四种强度不同的酸性位,且其主要酸性中心(SO3H)具有两种不同的热稳定性。     

Ionic Polymer‐Metal Composite Actuators Employing Radiation‐Grafted Fluoropolymers as Ion‐Exchange Membranes

Summary: To develop ionic polymer‐metal composites (IPMC) with improved performance, three new ion‐exchange membranes were prepared and employed in IPMC construction. The membranes were prepared by radiation‐grafting of polystyrene sulfonic acid onto three fluoropolymers; poly(vinylidenefluoride‐co‐hexafluoropropylene), poly(ethylene‐co‐tetrafluoroethylene), and poly(tetrafluoroethylene‐co‐hexafluoropropylene). The bending displacements of the IPMCs constructed with these membranes were at least several times larger than that of Nafion IPMC of similar thickness without straightening‐back. The larger displacement was considered to be due to the higher concentration of ionic groups and consequent larger ion‐exchange capacity.

Actuation of (a) Nafion IPMC and (b) IPMC prepared in this study.     

Super-Hydrophobic,Stable, and Swelling Nanoporous Solid Strong Acid

Super-hydrophobic solid strong acid with superior thermal stability and unique swelling properties has been synthesized by sulfonation of nanoporous polydivinylbenzene (PDVB) with super-acid of trifluoromethanesulfonic acid (TFMSA). The resultant PDVB–HOSO₂CF₃ has a well developed system of nanopores, superhydrophobic surface character and strong acid sites, and could be used as a highly efficient solid acid for catalyzing production of biodiesel and fine chemicals via transesterification, esterification and acylation. In terms of activity PDVB–HOSO₂CF₃ is superior to various solid acids such as SBA-15-SO₃CF₃, Nafion, Amberlyst 15, SBA-15-Ar-SO₃H and H form USY. The preparation of PDVB–HOSO₂CF₃ offers the way to develop new kind of porous solid acid with strong acid strength and regulated wettability.     

Etherification of dimethylbutene with methanol over clay-based acid catalysts

Etherification of a typical C₆ olefin, 2,3-dimethyl-1-butene, with methanol was investigated over commercial ion-exchange resins and several clay-based acid solids prepared by sulfuric acid treatment or impregnation of sulfated zirconia and Nafion. The commercial resin catalyst Amberlyst 15 is effective but nonselective to ether production, while Nafion is less active. For two clay systems, montmorillonite-based catalysts generally exhibit higher activities than bentonite and MT-H₂SO₄will be a highly active and selective catalyst than the supported sulfated zirconia and Nafion.     

C9 Fraction Alkylation Desulfurization over Amberlyst 36 Resin:The Kinetics of 2‐Ethylthiophen, 2,5‐Dimethylthiophene,and 2‐n‐Propylthiophene with Isoamylene

C₉ fraction is the by‐products of catalytic reforming and ethylene cracker; it is considered as a kind of petroleum resin raw material. Recently, it was studied for the use as a gasoline additive to enhance the economic benefits. However, C₉ fractions are getting higher in sulfur contents. As conventional hydrotreating technology leads to significant octane number loss and processing costs, the alkylation desulfurization process, which could reduce the sulfuric compounds to hydrogen sulfide by catalytic alkylation with olefins and distillation followed by, is a rather attractive way of reducing the sulfur of C₉ fraction. In this paper, different kinds of thiophenic compounds, including 2‐ethylthiophen, 2,5‐dimethylthiophene, and 2‐n‐propylthiophene, were selected as the model compounds. Thiophenic compounds were studied first by the alkylation reaction over macroporous sulfonic resin Amberlyst 36, and the octane number of C₉ fraction was measured. It was found that isoamylene and Amberlyst 36 resin had a significant effect on the alkylation desulfurization of thiophenic compounds with the conversion, reaching to above 99%. And the octane number of C₉ fraction was increased by alkylation desulfurization over Amberlyst 36 resin. Moreover, the alkylation of thiophenic sulfurs could be described as a pseudo–first–order reaction as well as the reaction rate constant, and the activation energy of alkylation reactions was calculated.     

Solution-phase parallel synthesis of carbamates as gamma-secretase inhibitors

A novel methodology for parallel liquid-phase synthesis of carbamates suitable for the preparation of sterically hindered molecules is disclosed. The alcohols are converted to 4-nitrophenylcarbonates, followed by the reaction with amines. Side product 4-nitrophenol and the unreacted excess amines are scavenged by appropriately chosen cleanup resins, selected among Amberlyst A26 (hydroxide form) and macroporous sulfonic acid (MP-TsOH) or polystyrene isocyanate (PS-NCO) and polystyrene benzaldehyde (PS-PhCHO) resins. As a part of a medicinal chemistry program directed toward finding gamma-secretase inhibitors as prospective drug candidates for Alzheimer's disease, a 6 x 24 library of carbamates was prepared. Out of 144 library members, 133 had a purity for the targeted compound of 80% or better. The prepared compounds were assessed in the gamma-secretase inhibition assay and demonstrated activity with IC 50 values in the range from 1 microM to 5 nM, with the activity of 7 compounds being better than 10 nM.     

固体超强酸研究的最新进展

简要介绍了近年来固体超强酸的发展。目前研究较多的固体超强酸有负载硫酸超强酸、Ｃｓ２．５盐、ＡｌＣｌ３／ＰＳ－ＤＶＢ磺酸树脂体系和全氟磺酸树脂（Ｎａｆｉｏｎ－Ｈ－Ｈ ＰＥＩＥＰ）四种。文章主要阐述了这几种固体超强酸的制备方法及它们的性质比较。     

Homogeneous and Heterogeneous Catalyzed Esterification of Acrylic Acid with Ethanol: Reaction Kinetics and Modeling

Kinetics of esterification of acrylic acid with ethanol in the presence of homogeneous (H₂SO₄, HCl, p‐TSA, HI) catalysts as well as heterogeneous catalysts (Dowex 50WX, Amberlyst 15) was studied. The effects and performance of these catalysts on the conversion of acrylic acid were evaluated. In the kinetics of homogeneous catalyzed reaction, both concentration and activity‐based model were employed. Activity coefficients were predicted by the Universal Functional group Contribution (UNIFAC) method to consider nonideal behavior of the liquid phase. The heterogeneous catalyzed reaction mechanisms were developed using Eley–Rideal theory. The model results were compared with the experimental results and were in good agreement. The temperature dependency of the constants, reaction enthalpy, and entropy, and activation energy were determined. The conversion of acrylic acid was obtained as 63.2%, 61.02%, 53.3%, 21.4%, 34.96%, and 14.84% for H₂SO₄, p‐TSA, HCl, HI, Dowex 50WX, and Amberlyst 15, respectively, under process temperature of 70°C, reactant molar ratio of 1:1, and catalyst concentration of 2% (v/v) for homogeneous and 2.17 g for heterogeneous catalyst. These outcomes provide an approach to understand the significant effect of each catalyst on the esterification kinetics of acrylic acid and ethanol.     

Polystyrene‐modified novolac epoxy resin/clay nanocomposite: Synthesis,and characterization

A polystyrene‐modified epoxidized novolac resin/montmorillonite nanocomposite was fabricated and characterized successfully. For this purpose, novolac resin (NR) was epoxidized through the reaction of phenolic hydroxyl group with epichlorohydrin in super basic medium to produce epoxidized novolac resin (ENR). Afterward, a polystyrene was synthesized by atom transfer radical polymerization (ATRP) technique, and then brominated at the benzylic positions using N‐bromosuccinimide (NBS). The brominated polystyrene (PSt‐Br) was reacted with ethanolamine in basic medium in order to afford an amine‐functionalized polystyrene (PSt‐NH₂). An organo‐modified montmorillonite (O‐MMT) was synthesized through the treatment of MMT with hexadecyl trimethyl ammonium chloride salt. Finally, ENR‐PSt/MMT nanocomposite was fabricated through curing a mixture of ENR (70 wt.%) and O‐MMT (5 wt.%) with PSt‐NH₂ (25 wt.%). Transition electron microscopy (TEM) and powder X‐ray diffraction (XRD) analysis revealed that the fabricated nanocomposite has an exfoliated structure. Thermal property studies using thermogravimetric analysis (TGA) showed that the curing of ENR by PSt‐NH₂, as well as incorporation of a small amount of MMT have synergistic effect on the thermal stability of the ENR resin.     

聚醚砜酮的磺化及其在异丁烯低聚反应中的应用

Concentrated homogeneous mineral acids have been widely used as catalysts in industrial processes for several decades. These catalysts are corrosive to the apparatus, and there are large volumes of chemically reactive waste stream that are difficult to deal with[1]. In order to solve these problems, investigators have replaced these mineral acids with solid acid catalysts. Besides inorganic solid acid catalysts such as zeolite, solid organic polymeric resins containing acid groups, especially sulfuric acid resins such as Amberlyst[2], have attracted much attention. Compared with most inorganic acid catalysts, they have the advantages of their potentially high acidity, controllable surface area and porosity[3]. This article reports a novel sulfonated poly(phthalazinone ether sulfone ketone) (S-PPESK) resin and its application to isobutene oligomerization. S-PPESK exhibits high catalytic activity and excellent dimerization selectivity.     

Efficient One‐Pot Solvent‐Free Synthesis of 1H‐Pyrazolo[1,2‐b]phthalazine‐5,10‐diones Catalyzed by Sulfonic Acid Functionalized Nanoporous Silica (SBA‐Pr‐SO3H)

A green protocol has been developed for the synthesis of 1H‐pyrazolo[1,2‐b]phthalazine‐5,10‐diones by one‐pot cyclocondensation reaction of phthalhydrazide, aromatic aldehydes, and malononitrile or ethyl cyanoacetate using sulfonic acid functionalized SBA‐15 (SBA‐Pr‐SO₃H) as a heterogeneous solid acid catalyst under solvent‐free conditions.     

Preparation of densely grafted poly(aniline‐2‐sulfonic acid‐co‐aniline)s as novel water‐soluble conducting copolymers

Various densely grafted polymers containing poly(aniline‐2‐sulfonic acid‐co‐aniline)s as side chains and polystyrene as the backbone were prepared. A styryl‐substituted aniline macromonomer, 4‐(4‐vinylbenzoxyl)(N‐tert‐butoxycarbonyl)phenylamine (4‐VBPA‐^tBOC), was first prepared by the reaction of 4‐aminophenol with the amino‐protecting moiety di‐tert‐butoxyldicarbonate, and this was followed by substitution with 4‐vinylbenzyl chloride. 4‐VBPA‐^tBOC thus obtained was homopolymerized with azobisisobutyronitrile as an initiator, and this was followed by deprotection with trifluoroacetic acid to generate poly[4‐(4‐vinylbenzoxyl)phenylamine] (PVBPA) with pendent amine moieties. Second, the copolymerization of aniline‐2‐sulfonic acid and aniline was carried out in the presence of PVBPA to generate densely grafted poly(aniline‐2‐sulfonic acid‐co‐aniline). Through the variation of the molar feed ratio of aniline‐2‐sulfonic acid to aniline, various densely grafted copolymers were generated with different aniline‐2‐sulfonic acid/aniline composition ratios along the side chains. The copolymers prepared with molar feed ratios greater than 1/2 were water‐soluble and had conductivities comparable to those of the linear copolymers. Furthermore, these copolymers could self‐dope in water through intermolecular or intramolecular interactions between the sulfonic acid moieties and imine nitrogens, and this generated large aggregates. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1090–1099, 2005     

Kinetic study on the dehydration of tert‐butyl alcohol catalyzed by ion exchange resins

The dehydration of tert‐butyl alcohol (TBA) in the liquid phase was studied by using an ion exchange resin, Amberlyst 15 (A15) in the H⁺ form. Experiments were carried out both in a semi‐batch reactor and in a continuous stirred tank reactor (CSTR) with wet or dry resins. The results with the dry resin in the semi‐batch reactor were different from those with the wet resin due to the swelling of resin in the presence of water. However, the results in CSTR agreed well with those in the semi‐batch reactor using the wet resin. A rate equation that considered the inhibition of water was formulated. The experimental results agreed well with the calculated ones. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 854–859, 1999