نتایج جستجو برای: silica boron sulfonic acid
تعداد نتایج: 794732 فیلتر نتایج به سال:
Homogenous bis-sulfonic acid ionic liquids (1 mol equiv.) in DMSO (10 mol equiv.) at 100 °C efficiently mediated the conversion of D-fructose into 5-hydroxymethyl-2-furfural in 75% isolated yield, which was roughly a 10% increment compared to the case of the mono-sulfonic acid ionic liquids.
Camphorquinone-10-sulfonic acid hydrate was prepared by the action of selenous acid on camphor-10-sulfonic acid. Camphorquinone-10-sulfonylnorleucine was prepared either from the sulfonic acid via the sulfonyl chloride or by selenous acid oxidation of camphor-10-sulfonylnorleucine. These reagents are useful for specific, reversible modification of the guanidino groups of arginine residues. Camp...
This study was carried out in order to determine the effects of boron and cold stress on pollen germination of almond hybrids in vitro culture, two different media including the absence and presence of boron (0 mg/l, and 100 mg/l) in 10% sucrose and 1% agar medium at 24°C in dark conditions. The results showed that different treatments had a significant effect on the germination percentage. The...
Boron deficiency and phytohormone interactions have been studied in unfertilized cotton (Gossypium hirsutum) ovules grown in vitro. Such ovules required exogenous indoleacetic acid and/or gibberellic acid for fiber elongation. Boron also was required for maintenance of fiber elongation and normal morphogenesis throughout 14 days of culture. The amount of exogenous boron necessary for maximum fi...
Biolubricants may be obtained from vegetable oils using appropriate chemical modifications, to improve their physicochemical properties for lubrication applications. In this study, the esterification of a free fatty acid (FFA) with long chain alcohols was performed sulfonated mesoporous silica as catalyst. Fresh and functionalized MCM-41 samples were prepared evaluate effect sulfonic surface gr...
A novel method was developed for the preparation of highly efficient anion- and cation-exchange microHPLC columns using an on-column polymerization of methacrylates having amine or sulfonic acid functional groups onto monolithic silica capillary columns modified with 3-methacryloxypropyltriethoxysilane as the anchor groups. The chromatographic evaluation of the columns using nucleic acids, nucl...
Nano-silica supported boron trifluoride (BF3.SiO2) is an efficient, reusable and eco-friendly catalyst for chemoselective thioacetalization of aldehydes and ketones. So, this catalyst was applied for transthioacetalization of acetals and acylals into their corresponding 1,3-dithiolanes or 1,3-dithianes in good to excellent yields. The reactions were carried out at room temperature under solven...
Elemental boron was isolated in 1808. It typically occurs in nature as borates hydrated with varying amounts of water. Important compounds are boric acid and borax. Boron compounds are also used in the production of metals, enamels, and glasses. In trace amounts, boron is essential for the growth of many plants, and is found in animal and human tissues at low concentrations. Poisoning in humans...
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