Topic
Reagent
About: Reagent is a research topic. Over the lifetime, 60091 publications have been published within this topic receiving 1234928 citations. The topic is also known as: reagens.
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TL;DR: In this paper, the introduction of the t-butyloxycarbonyl protecting group into amino-acids by a new method, using the stable t-Butyloxy carbonyl azide (III) was described.
Abstract: The introduction of the t-butyloxycarbonyl protecting group into amino-acids by a new method, using the stable t-butyloxycarbonyl azide (III), is described. Over previous methods the new procedure offers obvious advantages owing to the stability of the reagent and the resulting good yields.
154 citations
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TL;DR: The mechanism of the enantioselective 1,4-addition of Grignard reagents to alpha,beta-unsaturated carbonyl compounds promoted by copper complexes of chiral ferrocenyl diphosphines is explored through kinetic, spectroscopic, and electrochemical analysis and a structure of the active catalyst is proposed.
Abstract: The mechanism of the enantioselective 1,4-addition of Grignard reagents to α,β-unsaturated carbonyl compounds promoted by copper complexes of chiral ferrocenyl diphosphines is explored through kinetic, spectroscopic, and electrochemical analysis. On the basis of these studies, a structure of the active catalyst is proposed. The roles of the solvent, copper halide, and the Grignard reagent have been examined. Kinetic studies support a reductive elimination as the rate-limiting step in which the chiral catalyst, the substrate, and the Grignard reagent are involved. The thermodynamic activation parameters were determined from the temperature dependence of the reaction rate. The putative active species and the catalytic cycle of the reaction are discussed.
154 citations
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154 citations
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TL;DR: Under optimal conditions, 99.25% degradation efficiency of dye in aqueous solution was achieved after 60 min of reaction, and the optimal reacting conditions were experimentally found to be pH 3.40, initial hydrogen peroxide concentration, initial ferrous concentration and initial pH.
154 citations
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TL;DR: In this paper, a colloidal cholesterol suspension is added in 10 ml. of warm acetone and poured into 100 ml of boiling water with vigorous stirring, and then 2 ml of cold acetic anhydride-sulfuric acid reagent is added to each sample.
Abstract: Publisher Summary In preparation of colloidal cholesterol suspension 0.5 g. of cholesterol is added in 10 ml. of warm acetone and poured into 100 ml. of boiling water with vigorous stirring. Floating particles and sediment are filtered. The residual acetone is removed by boiling in vacuo when it is desirable to eliminate this component from the reaction mixtures. Colloidal ergosterol suspension is prepared in same manner. Cholesterol and ergosterol is assayed by Liebermann-Bulchard reaction. The samples to be assayed are adjusted to 80% (v/v) ethanol-acetone (1:1) to deproteinize the reaction mixtures and extract the cholesterol. This is conveniently carried out by transferring the reaction mixture to a centrifuge tube and rinsing the reaction vessel with small aliquots of ethanolacetone until the desired amount has been added to the tube. The precipitate is extracted with approximately 0.5 vol. of warm ethanol-acetone for 5 to 10 minutes in a water bath (40 to 50 °) to effect complete recovery of the cholesterol. When the samples are completely dry, 5 ml. of chloroform are pipette into each tube. Then 2 ml. of cold acetic anhydride-sulfuric acid reagent are added to each sample and mixed by swirling. The tubes are placed in a 16 to 18 ° water bath, and the color allowed to develop for 15 minutes. The blue-green color is measured immediately at 625 mu and compared with a standard curve over the range of 0.1 to 0.5 mg. of cholesterol. Standards is included with each assay.
154 citations