Catalytic reactions of Activated Tungstic Acid PDF

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CATALYTIC REACTIONS OF ACTIVATED TUNGSTIC ACID[Author Name(s), First M. Last, Omit Titles and Degrees][Institutional Affiliation(s)]
Catalytic Reactions of Activated Tungstic AcidAimsThis study utilized a series of laboratory experiments to explore the feasibility of a method thatwas developed to produce activated tungstic acid frompartial dehydration of tungstic acid. Thismaterial is a far more active catalyst than tungstic acid, often reacting with substrates at roomtemperature where tungstic acid required temperatures in excess of 100 ̊C. The exploration of thecatalytic transformations ofvarious alkenesand unsaturated five-membered ring heterocycles(e.g. indoles, pyrroline, and dihydrofuran) with the new catalyst is done. Compoundswereidentified by comparison of their mass spectra to the NIST database. Product identity wasconfirmed by measuring the retention times of authentic samples of the compounds identified bymass spectroscopy.IntroductionTungstic acid is any forms of hydrated tungsten trioxide. The simplest forms of the acid are themonohydrate whose chemical formula is WO3.H2O as well as dehydrate with a chemical symbolWO3. 2H2O. the structure of a solid monohydrate form of tungstic acid is composed of layers ofWO5(H2O) units that have been coordinated in an octahedral manner in which 4 vertices areshared in the structure. The same is found in the dehydrate structure with the extra molecule ofwater being intercalated between the layers in the structure. The monohydrate layer is yellow incolor and often insoluble in water. The acid is called acid of Wolfram as a classification nameand was discovered in 1781 by a scientist called Carl Wilhelm Scheele[ CITATION YAA12 \l 1033 ].Tungsticacid is prepared through the actions of strong acids on alkali metallic tungstate. Still, itmay be prepared through the reaction between hydrogen carbon and sodium tungstate. Another
way of achieving the tungstic acid is obtaining it from pure tungstate through reaction withhydrogen peroxide.MethodologyReactions between the alkenes and partial dehydration of tungstic acid were carried out at 150 ̊Cfor 24 hours and then cooled. The reactions were carried out inGlass culture tubes with screwcapsbombs using an excess of the partial dehydration of tungstic acid (2.5 g) and 0.25 g of thecycloamines[ CITATION Fel17 \l 1033 ]. The sealed reactors were placed in a digitally-controlledoven at various temperatures under autogenous pressure. The number of reactants and productsin the reaction mixtures were determined by cooling the bombs, sampling the headspace with agas-tight syringe, and analyzing by gas chromatography/ mass spectroscopy. Compounds wereidentified by comparison of their mass spectra to the NIST database. Product identity wasconfirmed by measuring the retention times of authentic samples of the compounds identified bymass spectroscopy. The products for the less volatile alkenes were isolated by extracting thereaction mixture with methylene chloride, and the extract was subjected to analysis by gaschromatography/mass spectroscopy[ CITATION DHR12 \l 1033 ].RESULTS AND DISCUSSIONTungstic acid is formed as a yellow precipitate in an amorphous formed when excess hothydrochloric acid is reacted with a solution of an alkali of tungstate[ CITATION Pie13 \l 1033 ]. Incase a cold acid is used instead of a hot acid, a white precipitate, H2WO4.H2O is formed wherefrom 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:
By fusion of the finely formed of the powered mineral using sodium chloride, calcium chlorideor even carbonates of alkalis- The residue formed in this reaction is treated with water thereafterhydrochloric or nitric acid so as to decompose any excess insoluble tungstates. Furtherpurification of the acid may be achieved by using a solution in ammonia and then precipitating itwith dilute nitric acid or chlorine.Using hydrochloric acid to digest a tungsten mineral and then use aqua regia until the iron andmanganese present in the solution dissolve and a yellow residue are left. The residue is thenwashed and shaken with ammonia that is meant to dissolve the free tungstic acid. The liquid isthen 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 precipitationtechnique.Tungstic acid is applied in mordant and dyes that are used in textiles. It is also used in thegeneration 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 andcellulose[ CITATION Siv14 \l 1033 ].Tungstic Acid has the general formula mWO3.nH2O and exists in numerous forms upon thecombination of Tungsten Trioxide WO3with each other at different ratios of water. Suchcombinations lead to the formation of polymer compounds. There are three main types oftungstic acid: yellow tungstic acid, white tungstic acid and partial tungstic acid.
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