Alkaline solution/binder ratio as a determining factor in the alkaline activation of aluminosilicates

This study investigates the effect of the alkaline solution/binder (S/B) ratio on the composition and nanostructure of the reaction products generated in the alkaline activation of aluminosilicates. The experiments used two mixtures of fly ash and dehydroxylated white clay and for each of these, varying proportions of the solution components. The alkali activator was an 8 M NaOH solution (with and without sodium silicate) used at three S/B ratios: 0.50, 0.75 and 1.25. The ²⁹Si, ²⁷Al MAS NMR and XRD characterisation of the reaction products reveal that for ratios nearest the value delivering suitable paste workability, the reaction-product composition and structure depend primarily on the nature and composition of the starting materials and the alkaline activator used. However, when an excess alkaline activator is present in the system, the reaction products tend to exhibit SiO₂/Al₂O₃ ratios of approximately 1, irrespective of the composition of the starting binder or the alkaline activator.     

助剂对煤基合成气甲烷化反应用镍基催化剂的促进作用

助剂促进的合成气甲烷化反应用镍基催化剂具有反应活性高、使用寿命长以及甲烷选择性高等优点,被广泛应用于煤基合成气甲烷化制替代天然气反应中。本文重点介绍了贵金属、碱土金属、稀土金属以及过渡金属助剂等对活性镍基催化剂的分散度、还原度、双金属合金协同效应、镍基催化剂结构稳定性及其对合成气甲烷化反应速率和产物选择性的影响。较系统地分析了这些助剂改性镍基催化剂的作用机制。提出了非贵金属助剂以及复合助剂将是合成气甲烷化用镍基催化剂助剂研发的发展方向,旨在为煤基合成气制替代天然气甲烷化催化剂的研发提供借鉴和参考。     

Investigation into Reactions of Starch with Monochlorotriazinyl-β-Cyclodextrin and Application of their Products in Textile Sizing

This article presents a study on the chemical modification of starch and hydrolyzed starches through their reactions with reactive cyclodextrin (RCD). Monochlorotriazinyl-β-cyclodextrin was investigated under a variety of conditions. The results obtained signify that the reaction was favored in an alkaline media rather than an acidic media, and in shorter rather than larger liquor ratios. Maximization of the reaction could also be achieved at 40°C for 60 min. Of the several alkaline catalysts used, NaOH proved to be the best when used at a concentration of 10 g/l. The reaction of starch and hydrolyzed starches with RCD was determined using a concentration of the latter. The apparent viscosity of the resulting polymeric products depends upon both the extent of reaction, expressed as a nitrogen percentage, and the degree of acid hydrolysis prior to the modification. Evidence for involvement of starch and RCD via chemical bonding was obtained through FT-IR analysis. Furthermore, the newly synthesized starch-based polymeric products were applied to a light cotton fabric and further evaluation of the sized materials was conducted by monitoring the size add-on, size removal, and strength properties of the fabric was conducted.     

Polarography of eosin and erythrosin in solutions of varying pH at the DME

The polarographic behaviour of eosin and erythrosin in buffer solutions of pH 4–11 is discussed. The observed waves are assigned to the reduction of furan and pyrone rings of the molecule of erythrosin at pH 4–11 and for eosin at pH ?7. The nature of the waves is also investigated. In alkaline media the electrode reaction is essentially diffusion controlled whereas at pH < 8 adsorption of the reduction products contributes in the electrodes process.     

Synthesis and application of long‐chain alkyl quaternary ammonium‐functionalized hyperbranched polyester

A novel kind of macromolecule, long‐chain alkyl quaternary ammonium functionalized hyperbranched polyester (QHPE), was synthesized by the reaction of hyperbranched polyester Boltorn H30 (H30) and 2,3‐epoxypropyl alkyl dimethyl ammonium chloride under alkaline conditions in dimethylformamide. After modification, the hydroxyl terminal group of H30 was converted into an ammonium functional group. A series of products was obtained with different lengths of an alkyl chain (C8, C12, C16, and C18) in the ammonium functional group. All of the products were characterized by Fourier transform infrared and NMR spectroscopy. The application of QHPEs as accelerators for the alkaline hydrolysis of poly(ethylene terephthalate) (PET) fabric was studied. The influences of the structure of QHPEs and hydrolysis conditions, such as alkaline concentration, hydrolysis time, and temperature, on the weight loss of PET fabrics were investigated. The results indicated that QHPE was a novel, efficient accelerator for the alkaline hydrolysis of PET fabrics. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

On the influence of stirring conditions on the dissolution rate of chalcogenide glasses and films

The local dissolution rates of chalcogenide films based on arsenic sulfide have been investigated in solutions of two types, i.e., alkaline aqueous solutions and amine solutions. The contribution of diffusion and hydrodynamic components to the total dissolution rate has been studied. It has been demonstrated that the possible contribution of the diffusion stages to the total rate of the interaction between the films and alkaline solutions is associated with the slow desorption of reaction products from the interface. The accumulation of interaction products in dipentylamine solutions favors an increase in the dissolution rate of the films, whereas the reaction products in the reaction with alkalis have an inhibiting effect. The difference between the used solvents of dipentylamine can lie in the difference between their abilities to form intermediate compounds with sulfur that have different nucleophilicities.     

一种催化新材料的孔结构与反应性能关联研究

在实验室研究了山西金洋土合成复合新型催化剂材料,并将其改性制成催化剂。在小型固定流化床装置上进行反应,采用XRD、静态N₂物理吸附法和热解吸色谱法等对催化剂进行表征。结果表明,山西金洋土在原位晶化体系中具有适度活性硅和较快活性铝的碱溶速率,有良好的晶化性能和裂化性能。经过水热处理和化学改性,形成了一定活性的中孔结构,设计的新型重油裂化催化剂具有较好的重油转化能力和良好的裂化产物选择性。     

Facile optical resolution of amino acid esters via hydrolysis by an industrial enzyme in organic solvents

Racemic amino acid esters were optically resolved via hydrolysis in organic solvents by the catalysis of an industrial alkaline protease, “Alcalase”. The products which were composed mainly of L-amino acids were insoluble and easily separated by filtration. The activity of the enzyme and enantiomeric excess of the products were significantly dependent on the nature of solvent and the water content in the reaction media. Generally, high values of enantiomeric excess were obtained at low water contents. Many natural and unnatural amino acids were resolved by this method.     

A Practical Total Synthesis of the Microbial Alkaline Proteinase Inhibitor (MAPI)

Diverse serine and cysteine proteases as well as alkaline proteinases and elastases play a crucial role in numerous biological processes. Natural peptide aldehydes such as the “microbial alkaline proteinase inhibitor” (MAPI, 1 ) are valuable tools to characterize novel enzymes and to study their function in nature. Within a drug discovery program we wanted to design and explore non‐natural MAPI congeners with novel biological profiles. To that end we devised a simple, practical, and scalable synthesis of MAPI 1 from readily available amino acid building blocks. The modular nature of our approach allows convenient structural modification of the MAPI backbone.     

Urea-formaldehyde resin structure formation under alkaline condition: a quantitative 13C-NMR study

The urea-formaldehyde (UF) reaction under strong alkaline condition was investigated by using quantitative analysis of ¹³C NMR. The main reaction products were methylolureas and oligomers linked by ether bonds at the beginning stage. With the reaction undergoing, the methylene linkages began to be formed and become predominant at the end point. The conversion of linear methylene ether bond to methylene linkage was also observed. These features were also observed previously for the reaction under acidic condition. It was found that the cyclic ether structure (uron) is much more stable than the linear ether bond, and its stability is second only to the methylene linkages among all the condensed structures. The formaldehyde was consumed in fast Cannizarro reaction under strong alkaline condition, producing considerable amount of methanol, which is the main negative aspect of this condition. With the exception of the differences caused by Cannizarro reaction, the UF production reactions under alkaline and acidic conditions are similar. The pH did not change the thermodynamic nature of the involved reactions, but only changed the competitive relationships of different reactions in kinetics.     

Improved synthesis of 1, 1, 1-Trimethylolalkanes from hexanal and nonanal

Reaction of hexanal or nonanal with formaldehyde under the usual conditions for the Tollens condensation gave the expected 1,1,1-trimethylolalkanes in 65–70% yields. Characterization of the crude product mixtures by silylation and subsequent gas-liquid chromatographic analysis permitted identification of by-products. The major by-products were the 2,2-bis(hydroxymethyl) alkanals resulting from incomplete reaction with formaldehyde; minor by-products were the formate esters of the hydroxymethyl compounds. These findings permitted modification of the procedure to give 1,1,1-trimethylolalkanes in 85–90% yields. The modifications included a) isolation from alkaline rather than acidic solution to prevent ester formation and b) hydrogenation of the crude reaction products to convert the 2,2-bis (hydroxymethyl) alkanals to the 1,1,1-trimethylolalkanes. No. Utiliz. Res. Dev., ARS, USDA.     

六氮杂[3.3.3]螺桨烷的多位点烷基化反应

以2,4,6,8,9,11-六氮杂[3.3.3]螺桨烷-3,7,10-三酮(PTO)为原料,通过与亲电试剂发生烷基化反应,获得了具有含能化衍生前景的六烯丙基六氮杂[3.3.3]螺桨烷、六乙氧羰甲基六氮杂[3.3.3]螺桨烷和六羧甲基六氮杂[3.3.3]螺桨烷;系统研究了不同亲电试剂与六氮杂[3.3.3]螺桨烷之间的反应活性,探讨了不同取代基六氮杂[3.3.3]螺桨烷化合物的酸碱稳定性和热稳定性。结果表明,不同取代基结构对于六氮杂[3.3.3]螺桨烷的骨架修饰具有显著影响,亲电试剂活性的增加和溶剂极性的增大对反应有利,但过高活性的亲电试剂因副反应过多无法获得相应的烷基化产物;烷基化取代后的六氮杂[3.3.3]螺桨烷体系的水解稳定性大大增加,酸性条件下可保持稳定而碱性条件下多数烷基化产物发生降解;烷基化取代的产物其热稳定性较PTO有所增强。     

The alkali-silica reaction in alkali-activated granulated slag mortars with reactive aggregate

The expansion of alkali-activated granulated blast furnace slag (AAS) cement mortars with reactive aggregate due to alkali-silica reaction (ASR) was investigated. The alkaline activator used was NaOH solution with 4% Na₂O (by mass of slag). These results were compared to those of ordinary portland cement (OPC) mortars. The ASTM C1260-94 Standard Test Method based on the NBRI Accelerated Test Method was followed. The nature of the ASR products was also studied by SEM/EDX. The results obtained show that the AAS cement mortars experienced expansion due to the ASR, but expansion occurs at slower rate than with OPC mortars under similar conditions. The cause of the expansion in AAS cement mortars is the formation of sodium and calcium silicate hydrate reaction products with rosette-type morphology. Finally, in order to determine potential expansion due to ASR, the Accelerated Test Method is not suitable for AAS mortars because the reaction rate is initially slow and a longer period of testing is required.     

Graft polymerization on magnetic polymer substrates

Functional monomers were graft polymerized onto substrates consisting of magnetic iron oxides in a crosslinked PVA matrix. Initiation was carried out with H₂O₂ and FeSO₄; other common chemical initiating systems proved unsuccessful. Peroxide treatment of the substrates must be carried out separately from the reaction with Fe²⁺ and monomer. The amount of grafting achieved is highly variable, depending on the nature of the monomer. Strong base and weak acid magnetic shell resins prepared by graft polymerization are useful in water treatment by flocculation and moving-bed ion exchange, respectively. A wider range of products can be obtained by chemical modification of grafted chains. The mechanism of grafting is discussed in an endeavor to explain the highly specific nature of the reaction.     

Succinoylation of wheat straw hemicelluloses with a low degree of substitution in aqueous systems

The reaction of wheat straw hemicelluloses with succinic anhydride in aqueous alkaline systems was studied. The products showed a rather low degree of substitution, ranging from 0.017 to 0.21. The effects of reaction times of 0.5–16 h, temperatures of 25–45°C, and molar ratios of succinic anhydride to anhydroxylose units in hemicelluloses of 1:5–1:1 on the succinoylation yield and degree of substitution were examined. With the reaction kept within a pH range of 8.5–9.0, a temperature range of 25–28°C, a reaction duration of 1–2 h, and a 1:1 molar ratio of succinic anhydride to hemicelluloses were preferred. The structure of the resulting polymers was determined with Fourier transform infrared and ¹H‐ and ¹³C‐NMR spectroscopy, which indicated monoester substitution. The thermal stability of the esterified polymer increased with chemical modification. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 757–766, 2002     

The selective hydrogenation of acetonitrile on supported nickel catalysts

The catalytic behavior of several supported nickel catalysts in the hydrogenation of acetonitrile was studied. It was established that the selectivity of this process is greatly influenced by the nature of the support used. Catalysts consisting of nickel supported on acidic supports catalyzed the formation of condensation products, diethyl- and triethylamine. Nickel supported on basic supports was highly selective with respect to the formation of the primary amine, ethylamine. It was shown that modification of the intrinsic acidity of alumina-based supports by the application of alkaline additives has a large impact on the selectivity of the resulting catalyst. Based on the results obtained from measurements on a basic catalyst diluted with either an acidic or a basic support, a dual-function mechanism is suggested. The mechanism implies that the hydrogenation function of the catalyst is located on the metal, while the acid function, responsible for the condensation reactions, is located on the support. A mechanism, accounting for the occurrence of the acid-catalyzed condensation reactions, is proposed.     

Analysis of cationic and amphoteric surfactants: V. structural analysis of the amphoteric surfactants obtained by the reaction of 1-(2-Hydroxyethyl)-2-alkyl-2-imidazoline with sodium monochloroacetate

Structural analysis of the amphoteric surfactants obtained by the reaction of l-(2-hydroxyethyl)-2-alkyl-2-imidazoline (HEAI) with sodium monochloroacetate has been carried out. These amphoteric surfactants were hydrolyzed under aqueous alkaline media, followed by acid hydrolysis to afford fatty acid and diamine derivatives. The resulting diamine derivatives were identified by the isolation and their syntheses, and were quantitatively analyzed by gas chromatography. Based upon the results of these analyses, it has been found that the reaction products can be divided into two typical types. The reaction products have simpler compositions than those of ethyl acrylate. However, these amphoteric surfactants are characterized by the presence of appreciable amounts of hydrolysis products of amides, soap and free diamine derivative XI.     

Gemeinsame Kondensation von Phenol,Melamin und Formaldehyd. I. Modellreaktionen

The condensation reaction between phenol, melamine, and formaldehyde was investigated by means of model reactions. For this purpose conversions of derivatives of phenol and aminotriazine were carried out under different reaction conditions. The reaction products were analysed by chromatographic and spectroscopic methods. By reacting melamine with p-methylolphenols under slightly-acidic conditions (pH 5 to 6) cocondensation products with methylene bridges are formed, whereas in strong acidic and alkaline medium only homocondensation products can be found.     

Reaction of 6-bromo-6-deoxycellulose with thiols in lithium bromide-N,N-dimethylacetamide

Nucleophilic substitution reactions of 6-bromo-6-deoxycelluloses of high degrees of substitution with eight thiols having functional groups such as carboxyl and amino groups were studied under homogeneous conditions in LiBr-N, N-dimethylacetamide in the presence of triethylamine. The reactions under the homogeneous conditions proceeded more extensively than those run under heterogeneous conditions in aqueous alkaline solutions. The reactivity of thiols was found to increase with increasing acidity of the mercapto groups of the thiols. Reaction products with 2-mercaptobutanedioic acid and with 2-mercaptobenzoic acid were soluble in alkaline and neutral water but not in 1 N HCl, while the reaction products with 2-aminoethanethiol did not dissolve even in 1 N HCl. The reaction products with cysteine showed amphoteric behavior. © 1996 John Wiley & Sons, Inc.     

塑料反应挤出改性进展

综述了用于塑料改性的反应挤出技术的接技、链间共聚、偶联／交联、可控降解及官能化等反应类型及改性机理，介绍了国内外PO、PVC、PS、ABS、PP等典型产品的反应挤出技术进展及应用情况。