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Catalytic reactions of Activated Tungstic Acid PDF

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Added on  2021-06-16

Catalytic reactions of Activated Tungstic Acid PDF

   Added on 2021-06-16

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CATALYTIC REACTIONS OF ACTIVATED TUNGSTIC ACID[Author Name(s), First M. Last, Omit Titles and Degrees][Institutional Affiliation(s)]
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Catalytic Reactions of Activated Tungstic AcidAimsThis study utilized a series of laboratory experiments to explore the feasibility of a method that was developed to produce activated tungstic acid from partial dehydration of tungstic acid. This material is a far more active catalyst than tungstic acid, often reacting with substrates at room temperature where tungstic acid required temperatures in excess of 100 ̊C. The exploration of thecatalytic transformations of various alkenes and unsaturated five-membered ring heterocycles (e.g. indoles, pyrroline, and dihydrofuran) with the new catalyst is done. Compounds were identified by comparison of their mass spectra to the NIST database. Product identity was confirmed by measuring the retention times of authentic samples of the compounds identified by mass spectroscopy.IntroductionTungstic acid is any forms of hydrated tungsten trioxide. The simplest forms of the acid are the monohydrate whose chemical formula is WO3.H2O as well as dehydrate with a chemical symbol WO3. 2H2O. the structure of a solid monohydrate form of tungstic acid is composed of layers of WO5 (H2O) units that have been coordinated in an octahedral manner in which 4 vertices are shared in the structure. The same is found in the dehydrate structure with the extra molecule of water being intercalated between the layers in the structure. The monohydrate layer is yellow in color and often insoluble in water. The acid is called acid of Wolfram as a classification name and was discovered in 1781 by a scientist called Carl Wilhelm Scheele[ CITATION YAA12 \l 1033 ]. Tungstic acid is prepared through the actions of strong acids on alkali metallic tungstate. Still, it may be prepared through the reaction between hydrogen carbon and sodium tungstate. Another
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way of achieving the tungstic acid is obtaining it from pure tungstate through reaction with hydrogen peroxide. MethodologyReactions between the alkenes and partial dehydration of tungstic acid were carried out at 150 ̊C for 24 hours and then cooled. The reactions were carried out in Glass culture tubes with screw caps bombs using an excess of the partial dehydration of tungstic acid (2.5 g) and 0.25 g of the cycloamines[ CITATION Fel17 \l 1033 ]. The sealed reactors were placed in a digitally-controlled oven at various temperatures under autogenous pressure. The number of reactants and products in the reaction mixtures were determined by cooling the bombs, sampling the headspace with a gas-tight syringe, and analyzing by gas chromatography/ mass spectroscopy. Compounds were identified by comparison of their mass spectra to the NIST database. Product identity was confirmed by measuring the retention times of authentic samples of the compounds identified by mass spectroscopy. The products for the less volatile alkenes were isolated by extracting the reaction mixture with methylene chloride, and the extract was subjected to analysis by gas chromatography/mass spectroscopy[ CITATION DHR12 \l 1033 ].RESULTS AND DISCUSSIONTungstic acid is formed as a yellow precipitate in an amorphous formed when excess hot hydrochloric acid is reacted with a solution of an alkali of tungstate[ CITATION Pie13 \l 1033 ]. In case a cold acid is used instead of a hot acid, a white precipitate, H2WO4.H2O is formed where from the acid may be obtained either through drying the compound over sulphuric acid or boilingthe mixture. Other methods that can be used in the preparation of the acid include:
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By fusion of the finely formed of the powered mineral using sodium chloride, calcium chloride or even carbonates of alkalis- The residue formed in this reaction is treated with water thereafter hydrochloric or nitric acid so as to decompose any excess insoluble tungstates. Further purification of the acid may be achieved by using a solution in ammonia and then precipitating it with dilute nitric acid or chlorine. Using hydrochloric acid to digest a tungsten mineral and then use aqua regia until the iron and manganese present in the solution dissolve and a yellow residue are left. The residue is then washed and shaken with ammonia that is meant to dissolve the free tungstic acid. The liquid is then filtered and when it reaches concentration, the tungstic acid present in it filters out[ CITATIONCha126 \l 1033 ]. By heating tungsten mineral under pressure using a solution of concentrated potash and lime. The tungstic acid will be separated from the final solution using fractional precipitation technique. Tungstic acid is applied in mordant and dyes that are used in textiles. It is also used in the generation of tungsten metals as well as its derivatives, a reagent for uric acid, plasma proteins, clinical analysis of blood and alkaloid. Tungstic acid is useful in fireproofing fabric and cellulose[ CITATION Siv14 \l 1033 ]. Tungstic Acid has the general formula mWO3.nH2O and exists in numerous forms upon the combination of Tungsten Trioxide WO3 with each other at different ratios of water. Such combinations lead to the formation of polymer compounds. There are three main types of tungstic acid: yellow tungstic acid, white tungstic acid and partial tungstic acid.
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