Chemically modified celluloses. XIII. Periodate oxidation of cellulose dyed with reactive and direct dyes in the presence of electrolytes

Periodate oxidation of cellulose dyed with vinyl sulfone-type reactive dyes at 32°C in the presence of various concentrations of alkaline earth metal chlorides and a cationic dye-fixing agent has been studied. The extent of the oxidation has been assessed in terms of rate constant, time of half reaction, and percent accessibility to periodate ions. Remazol Black B was used in the study. This dye on reduction with sodium hydrosulfite after reaction with the fiber removes the sulfonic acid group containing a portion of the dye, leaving behind a portion reacted with the fiber and not containing a sulfonate group. The study has also been extended to a few direct dyes which, unlike reactive dyes, have been shown not to inhibit the rate of periodate oxidation of cellulose.     

四氯化硅催化氢化制备三氯氢硅

针对四氯化硅氢化反应,采用等体积浸渍法制备了以HZSM-5为载体,金属氯化物为活性组分的负载型四氯化硅氢化反应催化剂,考察了催化剂的催化性能,并进行了相应表征。结果表明,碱土金属氯化物对四氯化硅氢化过程有良好的催化效果,在BaCl2负载质量分数为1%和反应温度850℃条件下,反应最高转化率为20.20%,选择性83.01%。     

金属氯化物对高温液态水中葡萄糖分解反应动力学的影响

以纤维素水解产物葡萄糖为模型物质,利用小型高压反应釜测定了180℃下13种金属氯化物催化葡萄糖和中间产物5-羟甲基糠醛(5-HMF)分解反应动力学数据,并用一级反应动力学模型对葡萄糖及5-HMF分解反应动力学数据进行了拟合。结果表明,不同的金属氯化物对葡萄糖和5-HMF的分解反应具有不同的催化效果,其中FeCl₃、NiCl₂和ZnCl₂可大大提高葡萄糖分解反应的速率,而FeCl₃和CuCl₂可大大提高5-HMF分解反应的速率。在碱金属、碱土金属和过渡金属氯化物中,过渡金属氯化物对葡萄糖及5-HMF分解反应的催化效果明显占优。对于第四周期金属元素,随着原子量的增加,葡萄糖分解反应速率常数呈现增加的趋势。金属氯化物对葡萄糖和5-HMF分解反应的催化活性随金属离子pK_a值的减小而增强。本文得到了金属氯化物对葡萄糖和5-HMF分解反应影响的规律,为生物质资源的高效利用提供了重要的基础数据。     

Visible Spectra of Standard Navy Colored Flares

The visible spectra, color data and output powers from standard U.S. Navy red, green and yellow signal flares are presented. The spectra were taken under essentially identical conditions on actual inservice U.S. Navy devices. The dominant emissions accounting for the output power in the flares are from the molecular bands of the alkaline earth oxides, hydroxides and chlorides in the red and green flares and from atomic sodium in the yellow flare.     

Selective Extraction of Lithium Chloride from Brines

Abstract

Lithium chloride can be recovered from brines by liquid-liquid extraction with alcohols such as n-butanol or isoamyl alcohol as well as by precipitation of the lithium aluminate complex (1–3). In most cases, however, certain amounts of magnesium chloride and calcium chloride are coextracted. In order to obtain pure lithium chloride, separation of alkaline earth compounds by special precipitation (4) or extraction procedures (5) is necessary. On the other side, coextraction of alkaline earth chlorides with alcohols can be suppressed by the addition of ammonia (6) or urea (7). For the separation of lithium from magnesium and sodium, extraction with mixtures of butanol and hexanediols is also recommended (8).     

Application of rare earth as mordant for the dyeing of ramie fabrics with natural dyes

Selecting appropriate metallic compounds as mordants is essential for dyeing with natural dyes. This paper presents the application of rare earth compounds as mordant for the dyeing of ramie fabrics with four kinds of natural dyes. The influences of pre-mordanting, simultaneous mordanting, and post-mordanting on the dyeing effect were explored. The post-mordanting was proved to give rise to the highest dye uptake. The effects of dyeing conditions including dyeing temperature and time, dyeing bath pH and the concentration of rare earth on the dye uptake were investigated systematically. The fabrics dyed with natural dyes in presence of rare earth as mordant exhibited high color shade stability in the baths with pH varying from being acidic to neutral and alkaline. Employing rare earth as mordant apparently raised the color fastness to washing, rubbing and light of the ramie fabrics dyed with the natural extracts. In comparison with the commonly used metallic salts, using rare earth chlorides as mordants can greatly reduce the ionic concentration employed in natural dyeing. This study proved that rare earth would be a kind or promising environmentally friendly mordant in natural dyeing.     

Effect of metal oxide additives on the CO hydrogenation to methanol over Rh/SiO2 and Pd/SiO2

Catalysts were prepared from ultra pure SiO₂, Pd and Rh nitrates and chlorides, and by doping with Al, Fe, Na, K or Ca nitrate. The activities and selectivities of the Pd and Rh catalysts were investigated at 553 K, H₂/CO=2 or 3 and 2.5 or 4 MPa respectively. Additives had a strong influence on the catalytic properties. The doping with alkali and alkaline earth oxides led to a strong suppression of the CO dissociation. Particularly basic additives, such as Ca, had a strong promoting effect on the methanol production. This may confirm that the formation of methanol occurs through formate intermediates.     

活性炭电极电容法脱盐性能的研究

研究了活性炭用于电容法脱盐时的电化学性能。用恒压充放电方法研究了操作电压对活性炭电吸附性能的影响,比较了活性炭对不同金属离子的电吸附性能,初步研究了活性炭物性参数与其电吸附性能的关系。结果表明,操作电压与活性炭电吸附容量呈线性关系(0.6~1.2 V),活性炭电极经恒压充放电循环后动态电吸附容量有一定的衰减,这可能与活性炭的表面官能团有关;4种活性炭对质量分数0.1%的碱金属和碱土金属氯化物吸附性能的比较发现,702#活性炭综合性能最好,对于KC l的吸附容量达27.9 mg/g,对NaC l的吸附容量达19.0 mg/g,对于MgC l2的吸附容量达17.0 mg/g;离子特性影响活性炭的电吸附性能;活性炭的比表面积和孔结构是影响活性炭电吸附性能的两个关键因素,比表面积较大、中孔较丰富的活性炭其电吸附性能更好。     

Mixed metal vinyl stabilizer synergism. II: Reactions with zinc replacing cadmium

The study of kinetics of displacement of reactive chlorine from a model compound, cinnamyl chloride, has been extended from barium/cadmium to barium/zinc and calcium/zinc carboxylate blends. With carboxylate ligands, the specificity of mixed metal complexes in yielding alkaline earth, rather than Lewis acid, chlorides is not as great with zinc as with cadmium. In the case of barium/zinc blends, this may be compensated for by complexing the metals with a ketoenolate ligand, e.g., benzoylacetone. In a mixed benzoyl-acetone/butyl acetate solvent, barium/zinc carboxylates yielded reaction rates with cinnamyl chloride comparable to barium/cadmium blends.     

Scandium Extraction from Chloride Solutions by a Mixture of Tributyl Phosphate and Molecular Iodine

It has been established that the addition of elemental iodine significantly enhances the extraction of scandium by means of tributylphosphate. The metal distribution coefficients exhibit an increase with increasing TBP and iodine concentration in the organic phase as well as with increasing chloride ion concentration in the aqueous phase. As an outsalting agent, chlorides of alkali, alkaline earth and other weakly extracted metal cations can be used. The process is promising for the extraction of scandium from solutions of hydrochloric- acid leaching of mineral and man-made materials.

     

On studies of oxide solubilities in melts based on alkaline halides

Studies of oxide solubilities (methods and results) in molten alkaline chlorides are considered. The scatter of literature data on oxide solubilities in molten KCl---NaCl has been explained by the effect of crystal grain sizes on their solubilities according to the Ostvald-Freindlich rule. Author's results of systematic oxide solubilities' studies in molten alkaline halides (KCl---NaCl, CsCl---KCl---NaCl, CsBr---KBr, CsI) are considered. Oxide solubilities in molten alkaline halides (pP) have been found to vary linearly with corresponding cation radii; such plots might be proposed for estimations of oxide solubilities in molten alkaline halides.     

用混合氯化稀土催化合成柠檬酸三丁酯

研究了氯化稀土对柠檬酸与正丁醇酯化反应的催化性能。结果表明,单一氯化稀土和混合氯化稀土均具有很好的催化活性。为此,系统地研究了混合氯化稀土催化合成柠檬酸三丁酯的工艺条件,确定了合适的工艺流程     

Effects of catalysis on gasification of Datong coal char

The effects of eleven catalysts on the steam gasification of Datong coal char were studied. The catalysts were oxides and chlorides of alkali and alkaline earth metals, separately or in combination. The catalytic effects of the NaCa composite on the reaction rate, methane conversion, steam decomposition and product gas composition and heating value were studied at reaction temperatures of 700–900 °C and pressures of 0.1, 1.1, 3.1 and 5.1 MPa. A kinetic equation of catalytic gasification was derived and the reaction rate constants and the activation energy at elevated pressure were determined.     

Alkaline earth metal catalysts for asymmetric reactions

The group 2 alkaline earth metals calcium (Ca), strontium (Sr), and barium (Ba) are among the most common elements on Earth, abundant in both the sea and the Earth's crust. Although they are familiar in our daily lives, their application to organic synthesis has, so far, been limited. Some particularly useful properties of these elements include (i) low electronegativity, (ii) a stable oxidation state of +2, meaning that they can potentially form two covalent bonds with anions, and (iii) the ability to occupy a variety of coordination sites due to their large ionic radius. Furthermore, the alkaline earth metals, found between the group 1 and group 3 elements, show mild but significant Lewis acidity, which can be harnessed to control coordinative molecules via a Lewis acid-base interaction. Taken together, these characteristics make the metals Ca, Sr, and Ba very promising components of highly functionalized acid-base catalysts. In this Account, we describe the development of chiral alkaline earth metal catalysts for asymmetric carbon-carbon bond-forming reactions. Recently prepared chiral alkaline earth metal complexes have shown high diastereo- and enantioselectivities in fundamental and important chemical transformations. We chose chiral bisoxazoline (Box) derivatives bearing a methylene tether as a ligand for chiral modification. These molecules are very useful because they can covalently coordinate to alkaline earth metals in a bidentate fashion through deprotonation of the tether portion. It was found that chiral calcium-Box complexes could successfully promote catalytic asymmetric 1,4-addition and [3 + 2] cycloaddition reactions with high diastereo- and enantioselectivities. Both the calcium-Box complexes and chiral strontium-bis-sulfonamide and chiral barium-BINOLate complexes could catalyze asymmetric 1,4-addition reactions with high enantioselectivities. Furthermore, we designed a calcium-neutral coordinative ligand complex as a new type of chiral alkaline earth metal catalyst. We found that pyridinebisoxazolines (Pybox) worked well: they served as excellent ligands for calcium compounds in 1,4-addition reactions and Mannich reactions. Moreover, they were successful in 1,4-additions in concert with enantioselective protonation, affording the desired products in good to high enantioselectivities. Our results demonstrate that alkaline earth metals are very useful and attractive catalysts in organic synthesis. Moreover, their ubiquity in the environment is a distinct advantage over rare metals for large-scale processes, and their minimal toxicity is beneficial in both handling and disposal.     

金属基催化剂催化不饱和烃的硼氢化反应研究进展

硼氢化反应是合成有机硼类化合物的主要方式之一,因其条件温和、操作简便、原子利用率高而受到广泛关注。过去几十年里,含Rh、Ir、Pb等贵金属的材料一直是硼氢化反应的首选催化剂,但其价格高、毒性大的特点限制了它们的广泛应用。近十年,碱土金属以及Fe、Co、Ni等廉价过渡金属因为储量丰富、价格低廉、催化效果良好,在催化硼氢化反应领域蓬勃发展,具有广阔的应用潜力。本文主要介绍了近年来过渡金属及碱土金属基材料催化不饱和烃硼氢化反应的研究进展。     

Low-temperature synthesis of sp 2-carbon structures with the use of polyvinylene chlorides—reactive polymers with a conjugation system

Chlorine-substituted polymers with a system of conjugated double bonds-polyvinylene chlorides, which form sp ²-carbon structures under unusually mild conditions, were prepared by the dehydrochlorination of carbon-chain perchloropolymers (chlorinated polyvinyl chloride and a polyvinyl chloride-polyvinylidene chloride composition) under the action of potassium hydroxide in organic media. The results of the potentiometric titration of the reaction medium in the synthesis of polyvinylene chlorides and the characterization of the products by Raman spectroscopy and thermal analysis with the mass spectrometry of the volatile products of thermal degradation confirmed the formation of polyvinylene chlorides under the selected dehydrochlorination conditions. It was hypothesized that the observed incomplete dehydrochlorination of the perchloropolymers is explained by the stabilization of polyvinylene chloride structures in the process of their formation by donor-acceptor interaction with an alkaline agent; this is consistent with the ability of the resulting polyvinylene chlorides to reversibly bind KON from solutions.     

有机磷(膦)酸对碱土金属的萃取

Solvent extraction equiliria of four main alkaline earth metals (magnesium, calcium, strontium and barium) with di(2-ethylhexyl) phosphoric acid (DEHPA), 2-ethylhexyl phosphonic acid mono-(2-ethylhexyl) ester, di(2,4,4-tri-methylpentyl) phosphinic acid and IR spectra of the extracts have been studied. The selectivity order is dependent of the e/r value and hydration energy of the metal ions. The minor shift of the P→O in IR absorption of the alkaline earth metal extracts indicates that the interaction between the metal ions and P→O is much weaker for alkaline earth metals than for transitional metals. The distribution of the four alkaline earth elements between aqueous solutions and solutions of DEHPA and neutral organophosphorus compunds, tri-n-butyl phosphate (TBP) or tri-octyl phosphine oxide (TOPO) in kerosene have been determined at varying ratio of TBP or TOPO to DEHPA and the positive synergism is observed. The synergic effects is explained by using IR spectra of the loaded organic phase.     

The mode of occurrence of chlorine in high volatile bituminous coals from the Asturian Central coalfield

The occurrence of chlorine in two high volatile bituminous coals from the Asturian Central coalfield, with a chlorine content about 0.1 wt % has been discussed. The methodology used is based on obtaining the chlorine distribution in different densimetric fractions in gravimetric solutions free of chlorides. It allows the separation of elements that could be bonded to chlorine to study their likely association. Additional information has been obtained by carrying out studies on the solubility in water, and the relation of chlorine with alkaline and alkaline-earth elements. Direct evidence of the presence of chlorine and its chemical association has been gained by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). From the results it may be concluded that in the coals studied chlorine is mainly localized in the coal matrix associated to organic matter.     

Electrochemical Recovery of Lithium Ions in the Aqueous Phase

Abstract

The electrochemical insertion of lithium ions into a Pt/λ-MnO₂ electrode was investigated in various metal chloride solutions. The Li⁺ insertion occurred effectively in LiCl solutions with higher concentration than 10 mmol/dm³, but it could hardly occur in a 0.1 mmol/dm³ LiCl solution. Alkaline earth metal ions showed a stronger inhibition effect against the Li⁺ insertion into the Pt/λ-MnO₂ electrode than alkali metal ions. However, since only Li⁺ ions were taken up from a mixed solution of lithium and alkaline earth metal chlorides, a high selectivity of the electrode for lithium ions was shown.

It was possible to recover lithium ions from geothermal water by this electrochemical method using the Pt/λ-MnO₂ electrode; the lithium uptake was 11 mg/g-MnO₂.     

The role of methyl radicals in the reduction of NO by CH4 over a Ba/MgO catalyst

The coproduction of methanol and isobutanol from synthesis gas over new catalysts based on coprecipitated solid solutions of alkaline earth oxides and rare earth oxides promoted by copper has been investigated. It is shown that the catalysts are active and selective to isoalcohol synthesis at temperatures and pressures lower than those required by prior art catalysts.