Iron (III) Perchlorate Adsorbed on Silica Gel: A Reagent for Organic Functional Group Transformations

Adsorption of Fe(ClO₄)₃(H₂O)₆ onto chromatographic‐grade silica gel in the presence of organic solvents (S=water, acetonitrile, or lower fatty acids) produces a supported reagent, Fe(ClO₄)₃(S)₆/SiO₂. This reagent has been found to be effective for the rapid organic functional group transformations such as dimerization of alkynes, aromatic hydrocarbons, selective oxidation of thiols to disulfides, and transannular reactions in 1,5‐cyclooctadienes on grinding using pestle and mortar in the solid state.     

Reaction in Dry Media: Silica Gel Supported Ferric Chloride Catalyzed Synthesis of 1,8-Dioxo-octahydroxanthene Derivatives

Herein, we describe a green procedure for the one-pot preparation of 1,8-dioxo-octahydroxanthene derivatives by condensation of dimedone and substituted benzaldehydes in the presence of FeCl ₃ -SiO ₂ as an efficient and heterogeneous catalyst under microwave irradiation and thermal conditions. This method has the advantages of high yields, cleaner reactions, efficient and cost-effective method, simple methodology, short reaction times, easy workup, and greener conditions.     

铁离子在多齿配体功能化硅胶上的吸附研究

以自制的多齿配体功能化硅胶为吸附剂,探究了配体齿数对废水中常见重金属离子吸附的影响.研究结果表明,五齿配体亚氨基二琥珀酸-硅胶吸附剂对铁离子(Fe3+)的吸附能力最强,吸附量为14.4 mg/g.进一步探讨了此吸附剂对Fe3+的吸附动力学和热力学行为,考察了Fe3+浓度、温度、转速以及共存离子对吸附的影响,并对吸附剂的...     

Sulfuric Acid Adsorbed on Silica Gel. A Multipurpose Acid Catalyst

A series of acid catalyzed reactions like the dehydration of alcohols, conversion of ketones to 1,3-dioxolanes and their hydrolysis, α,β-unsaturated ketones to enol ethers, and alcohols to methyl-methoxyethyl ethers are performed efficiently in high yield with sulfuric acid adsorbed on silica gel as catalyst.     

Silica Gel Supported Ferric Perchlorate: A New and Efficient Reagent for One Pot Synthesis of Amides from Benzylic Alcohols

Benzylic alcohols react efficiently with nitriles in the presence of silica gel supported ferric perchlorate to produce amides in high yields.     

Correlation Between Specific Surface Area and Methyl Red Adsorbed on Silica Gel

Abstract

The amount of methyl red, adsorbed on bare silica gel, has been determined for 32 samples having a specific surface area ranging from 10 m²/g to 500 m²/g, as determined by a BET method. A linear relationship between amount of dye adsorbed and specific area exists up to about 300 m²/g. Beyond this value the amount of adsorbed dye does not increase correspondingly, which is believed to be due to the relative increase of micropores in the silica gel structure. It is proposed that the easily performed determination of the adsorbed methyl red can serve to estimate that part of the silica gel surface which is available for chromatographic interactions.     

Selective Adsorption of Arsenic Ions on Silica Gel Impregnated with Ferric Hydroxide

Abstract

Selective adsorption of trace arsenite- and arsenate anions in an aqueous solution by ferric hydroxyde supported on silica gel particles was investigated. Silica gel particles were loaded with ferric hydroxide of the range of 1 – 3 wt. % in terms of Fe based on the dry gel, and the extent of adsorption of arsenite or arsenate ion measured by batch- and column processes, being the highest at pH 6 in the presence of diverse foreign ions. With the use of silica gel containing 3.3 wt. % Fe, as much as 0.07 m mol of arsenic per gram of dry gel was adsorbed.     

脂肪酶直接与硅胶混合催化无溶剂酯化反应的研究

用硅胶作为载体，以癸酸与己醇的酯化反应作为模型，将脂肪酶和底物直接与硅胶混合，用于无溶剂体系催化酯化反应．结果表明体系中水的含量、底物用量比以及反应时间均对酯化反应有较大影响．在该体系中，脂肪酶催化酯合成反应的速度显著增加，反应2h后．转化率可以达到90％以上．而且沉积在硅胶上的脂肪酶可以反复使用多次．     

盐酸三甲胺三氧化铬／硅胶载体试剂的制备及其对苯偶姻体系的氧化

报道了盐酸三甲胺三氧化锆／硅胶载体试剂的制备方法及其对苯偶姻的氧化反应。该试剂制备简单，用于地苯偶姻的氧化，高收率地得到相应的苯偶酰在化合物，并且反应条件温和，产物易分离。     

Amperometric Biosensor for Lactate Based on Meldola's Blue Adsorbed on Silica Gel Modified with Niobium Oxide

A reagentless amperometric biosensor sensitive to lactate was developed. This sensor comprises a carbon paste electrode modified with lactate dehydrogenase (LDH), nicotinamide adenine dinucleotide (NAD⁺) cofactor and Meldola's blue (MB) adsorbed on silica gel coated with niobium oxide. The amperometric response was based on the electrocatalytic properties of MB to oxidize NADH, which was generated in the enzymatic reaction of lactate with NAD⁺ under catalysis of LDH. The dependence on the biosensor response was investigated in terms of pH, supporting electrolyte, ionic strength, LDH and NAD⁺ amounts and applied potential. The biosensor showed an excellent operational stability (95% of the activity was maintained after 250 determinations) and storage stability (allowing measurements for over than 2.5 months, when stored in a refrigerator). The proposed biosensor also presented good sensitivity allowing lactate quantification at levels down to 6.5×10^?6 mol L^?1. Moreover, the biosensor showed a wide linear response range (from 0.1 to 14 mmol L^?1 for lactate). These favorable characteristics allowed its application for direct measurements of lactate in biological samples such as blood. The precision of the data obtained by the proposed biosensor show reliable results for real complex matrices.     

Photoprotolytic Reactions in Systems Immobilized on Silica Gel Using a Cationic Polyelectrolyte

Moscow University Chemistry Bulletin - The patterns of protolytic reactions in the immobilized state are studied using the example of classical systems with photoinduced proton transfer (2-naphthol...     

Chromatography of Some Metal Ions on Silica Gel Thin Layers in Butanol-Formic Acid Media

Abstract

Chromato graphic behaviour of some metal ions on silica gel thin layers has been studied in butanol—formic acid media. The results have been compared with those obtained in aqueous formic acid medium. Many important and analytically difficult separations have been achieved. Some thin layer chromato graphic parameters for the separation of Vo²⁺ from numerous metal ions using 20.0 M formic acid in butanol have been determined.     

用吸附数据对硅胶表面的分形分析

根据一种中孔硅胶对甲酸、乙酸、丙酸和四氯化碳蒸气吸附等温线的单层区域和毛细凝结区域的数据以及自四氯化碳稀溶液中吸附系列脂肪醇的结果计算了该硅胶表面分形维数D.除了由吸附四氯化碳等温线毛细凝结区域所得D值低于2外,由其它吸附数据得出的该硅胶的分维D近似相等(D=2.06±0.05).中孔硅胶低D值可用其孔结构特性解释.     

Methylammonium Chlorochromate Adsorbed on Silica Gel for Regeneration of Carbonyl Compounds from their Nitrogen-Containing Derivatives Under Mild and Non-Aqueous Conditions

Oximes, p-nitrophenylhydrazones, 4-phenylsemicarbazones and semicarbazones are converted to their corresponding carbonyl compounds in good yields using methylammonium chlorochromate adsorbed on silica gel(MCC/SiO₂) under mild and non-aqueous conditions.     

A Residue Technique for Urea Herbicides Using Catalytic Hydrolysis on Silica Gel Plates

Abstract

Urea herbicides are catalytically hydrolyzed to the corresponding aniline. The reaction occurs in situ on silica gel TLC plates making use of the acidic silanol groups. The anilines are then further reacted in situ with dansyl chloride and the fluorescent derivatives separated on the same plate. The sensitivity and selectivity of this technique permit the analysis of urea herbicide residues in soil and water samples with good reproducibility and a minimum of sample clean-up.     

Detection of a Covalent—Ionic Carbinolamine Intermediate in Aqueous Media by SDTLC on Silica Gel Plates

JPC – Journal of Planar Chromatography – Modern TLC - When the components of a reaction mixture cannot be quantified by UV-visible spectrophotometry, because the λmax values of...     

Morpholine Adsorbed on Silica Gel: A Novel and Mild Basic Catalyst for the Synthesis of α,β-Unsaturated Nitroalkenes

Summary.  Syntheses of α,β-unsaturated nitroalkenes have been carried out under mild condition using morpholine adsorbed on silica gel as a novel catalyst. Received February 14, 2000. Accepted March 28, 2000     

Ammonium Chlorochromate Adsorbed on Silica Gel: A New Reagent for the Oxidation of Alcohols and Benzoins to Corresponding Carbonyl Compounds

A new reagent, Ammonium chlorochromate adsorbed on silica gel, suitable for the oxidation of alcohols and benzoins to the corresponding carbonyl compounds is described.     

Morpholine Adsorbed on Silica Gel: A Novel and Mild Basic Catalyst for the Synthesis of α,β-Unsaturated Nitroalkenes

 Syntheses of α,β-unsaturated nitroalkenes have been carried out under mild condition using morpholine adsorbed on silica gel as a novel catalyst.