Sharif Digital Repository

4-Aminopyridinium chlorochromate supported on silica gel was found to be an efficient reagent for the oxidation of primary and secondary alcohols to the corresponding carbonyl compounds. © Springer-Verlag 2004  

A mixture of cobalt(II) and manganese(II) salts of 4-aminobenzoic acid supported on silica gel catalyses the oxidation of thiols to disulfides in the presence of oxygen or air  

A 1:1 molar ratio of the cobalt and manganese salts of p-amino benzoic acid supported on silica gel is an effective catalyst for the oxidation of various organic compounds in reasonable yields using molecular oxygen. The catalyst can be reused several times  

2-Mercaptobenzimidazole, loaded on silica gel (MBI-SG) was used for preconcentration and speciation of iron(II) and iron(III) in water samples. The speciation is based upon selective retention of iron(III) on MBI-SG sorbent and quantitatively passing iron(II) ions. This type of sorbent was not only capable of separating theses two ions but also could concentrate them. The adsorbed iron(III) on MBI-SG was desorbed from the column by an SCN- solution and transferred to the detection device. The effluent, then, was treated with hydrogen peroxide to oxidize iron(II) into iron(III) and subsequently was pumped through the MBI-SG column. A home-made flow injection system was coupled with a UV-VIS... 

Various alkyl, aryl, and heterocyclic Hantzsch 1,4-dihydropyridines were converted to the corresponding pyridines in excellent yields and short times using sodium nitrite in the presence of a catalytic amount of acidic silica gel at room temperature. © Springer-Verlag 2006  

4-Aminoperoxybenzoic acid supported on silica gel in presence of oxygen or air was found to be a convenient and selective oxidant for the oxidation of benzylic methylene compounds to the corresponding ketones  

Nowadays, the world is facing a shortage of fresh water. Utilizing adsorbent materials to adsorb air moisture is a suitable method for producing freshwater, especially combining the adsorption desalination system with solar energy devices such as solar collectors. The low temperature of solar collectors has caused some water to remain in the adsorbents in the desorption process and has reduced the possibility of using these systems. In this research, for the first time, an evacuated tube collector (ETC) is used as an adsorbent bed so that the temperature of the desorption process reaches higher values and as a result, more fresh water is expected to produced. In this study, two adsorption... 

A very efficient and mild procedure for the trimethylsilylation of a wide variety of alcohols, including primary, allylic, benzylic, secondary, hindered secondary, tertiary, and phenols with hexamethyldisilazane on the surface of silica gel dispersed with LiClO4 in room temperature at few minutes in excellent yields under neutral conditions is reported. This procedure also allows the excellent selectivity under LP-SiO2 system for silylation of alcohols in the presence of amine and phenolic hydroxy groups  

Iodic acid supported on wet silica gel and K10 clay are used for the efficient oxidation of benzylic alcohols under microwave irradiation and solvent free condition  

A new, simple and sensitive method for the simultaneous determination of mercury(II) and methylmercury chloride at sub-ng 1-1 levels in river waters is described. Inorganic and organic mercury were preconcentrated from fresh water samples simultaneously on a laboratory-made column containing 2-mercaptobenzimidazol loaded on silica gel and then quantitatively eluted with 0.05 M KCN solution and 2.0 M HCl to desorp inorganic and methylmercury species, respectively. After irradiation with an intensive UV source, MeHg+ was decomposed and mercury vapours were generated from inorganic and organic mercury using an acidic SnCl2 solution in a continuous flow system and were subsequently determined... 

4-Aminoperoxybenzoic acid supported on silica gel was found to be a versatile and efficient oxidant for the oxidation of ketones to esters. Copyright © Taylor & Francis Group, LLC  

A very efficient and mild procedure for the trimethylsilylation of a wide variety of alcohols, including primary, allylic, benzylic, secondary, hindered secondary, tertiary, and phenols with hexamethyldisilazane on the surface of silica gel dispersed with LiClO4 in room temperature at few minutes in excellent yields under neutral conditions is reported. This procedure also allows the excellent selectivity under LP-SiO2 system for silylation of alcohols in the presence of amine and phenolic hydroxy groups. © 2005 Elsevier B.V. All rights reserved  

4-Amino-2-chloroperbenzoic acid supported on silica gel was found to be a versatile and efficient oxidant for the oxidation of aldehydes and ketones to the corresponding carboxylic acids and esters. Copyright © Taylor & Francis, Inc  

Oxidative deprotection of silylethers, acetals and ketals, to their corresponding alcohols, aldehydes and ketones have been achieved using oxygen or air in the presence of cobalt and manganese salts of 4-aminobenzoic acid supported an silica gel as catalysts. Reactions are clean and catalysts can be recovered easily and reused repeatedly  

The simultaneous control of the molecular weight, separation, and purification of polyvinyl acetate was achieved using a cobalt-mediated radical polymerization (CMRP) in a packed column with silica gel particles (PC-CMRP). The controlled radical polymerization of VAc in the packed columns was evaluated from the linear time dependence of Ln[M]0/[M], linear increase of molecular weight with the increase in conversion, and narrow molecular weight distribution. PC-CMRP method was used to produce high-purity polymers with controlled molecular weight and narrow molecular weight distribution without requiring additional purification steps. The high ability of silica gel particles to adsorb free... 

Silica gel-confined ionic liquid (IL) is a class of heterogeneous catalysts with broad catalytic applications. Leaching of the IL from the surface of the support is the major drawback of these catalysts, which reduce the catalyst efficiency during the chemical reactions. To investigate the effect of the hydrogen bonding on the leaching phenomena, the interaction between the 1-ethyl-3-methylimidazolium-based IL with various anions (Cl-, Br-, HSO4 -, NO3 -, BF 4 -, and PF6 -) and the surface of the silica gel were studied using density functional theory. Hence, a hydroxylated cage-like cluster of silica gel, Si4O6(OH), was selected to mimic the surface. The values of ÎEinteraction show that... 

A novel mesoporous silica-functionalized dual Brønsted acidic species has been introduced as an efficient catalyst for solvent-free esterification of fatty acids with ethanol. The structure of the catalyst has been characterized by FT-IR spectroscopy, thermal gravimetric analysis (TGA), TEM and N2 adsorption-desorption. TGA of catalyst 1 showed no weight loss before 200 °C, indicating a high degree of hydrophobicity of the surface of the mesoporous silica. TEM images and nitrogen adsorption-desorption showed no noticeable changes to the structure of the catalyst before and after acid treatment. pH metric analysis was performed for the catalyst to determine the loading of the acidic sites.... 

Industrial-scale production of aromatic materials is confronted by the problem of removal of impurities such as olefins. Their removal is an essential requirement in marketability. Catalytic adsorbent clay is the most common material used for the removal of olefins from aromatic streams. The current study is focused on increasing the lifetime of a commercial type of clay by identifying the effective parameters in reducing the adsorbent lifetime. An analysis of 3 years of data from a petrochemical complex showed that water, morpholine, and N-formyl morpholine (NFM) contents in the feed stream are the factors reducing the clay lifetime. Various experiments have been performed to determine the... 

In the present study, we attempt to synthesize and characterize novel CMC-g-poly (acrylic acid-co-2-acrylamido-2-methylpropanesulfonic acid)/silica gel composite. Infrared spectroscopy and TGA thermal analysis were carried out to confirm the chemical structure of the hydrogel. Moreover, morphology of the samples was examined by scanning electron microscopy. The effect of reaction variables affecting on water absorbency of the composite and swelling behavior in various solvents, salt, and pH solutions was investigated. Maximum water absorbency of the optimized final product was found to be 4000 g/g in distilled water. The absorbency under load (AUL) of the hydrogel was also determined by... 

Rhamnolipids are the most common biosurfactants and P. aeruginosa strains are the most frequently studied microorganisms for the production of rhamnolipids. Eco-friendly advantages and promising applications of rhamnolipids in various industries are the major reasons for pursuing the economic production of these biosurfactants. This study shows that cultivation of P. aeruginosa MR01 in medium contained inexpensive soybean oil refinery wastes which exhibited similar levels and homologues of rhamnolipids. Mass spectrometry indicated that the Rha-C10-C10 and Rha-Rha-C10-C10 constitute the main rhamnolipids in different cultures of MR01 including one of oil carbon source analogues. Moreover,...