h) Synthesis of β-arylvinyl bromides 

Roy and Bhar reported the synthesis of several β-arylvinyl bromides under environmentally friendly conditions (using water as solvent) through a bromodecarboxylation reaction of cinnamic acids with potassium bromide, using 30% hydrogen peroxide as oxidant and sodium tungstate dihydrate as catalyst, with moderate to good yields.


 

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The kinds of tungsten chloride have tungsten hexachloride, tungsten pentachloride, tungsten tetrachloride, tungsten dichloride, is an important raw material for new applications. It is based on tungsten carbene material which catalyzes paraffin 1- and 2- octene substitution reaction. Besides promote 1, 3-dithiolane and 1, 3-dithiane converted into chloride dihydro-1, 4-dithiins and dihydro-1, 4-dithiepines.

Tungsten chloride, also known as tungsten hexachloride, its physical properties are: formula WCI6, the molecular weight of 396.56 and a melting point 275 ℃, boiling point 347 ℃, the density of 3.52. Its chemical properties are: can decomposition in water and can be dissolved in CS2, soluble in chloroform, methanol, ether, acetone, pyridine, glycerol, petroleum ether, ethanol, carbon tetrachloride, phosphorus oxychloride, benzene, and it easily oxidized in air. Related system number of tungsten chloride is: CAS: 13283-01-7, MDL: MFCD00011463, SNILES: Cl [W] (Cl) (Cl) (Cl) (Cl) Cl, EINECS: 236-293-9. Tungsten chloride is sensitive to moisture so it should be sealed in a cool place. Tungsten chloride hydrogen reduction rationale: the characterized of tungsten chloride hydrogen reduction is there has a variety of low-cost chlorides which accompany series of decomposition reactions and disproportionation reactions.

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g) Halogenation of aromatic compounds

The regioselective halogenation of some aromatic substrates using KCl or KBr in the presence of sodium perborate (SPB) as oxidant and sodium tungstate dihydrate as catalyst, is an environmentally friendly catalytic halogenation procedure, which can provide good yields(up to 92%) under mild conditions.


 

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Technical requirements of tungsten points in interrupter as described below:
Brazing material purity should be higher than 99.9%;
The strength of weld seam must be higher than 78.45MPa;

Tungsten points, which are welded and manufactured in hydrogen and nitrogen gas condition, are consisting of tungsten sheet, sit nails and the solder;

Test of tungsten sheet should be according to regulations in JB / T9860.2 and its main technical parameters are as follows:
With purity of more than 99.95%;
With hardness of higher than 70HRA;
With crystals number: 7500-25000 points / mm²;

Sit nail material is low carbon steel with 0.15% -0.20% carbon content, you can also adopt other materials which have similar composition and properties and can easily caulk.


 

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f) Oxidation of organosulfur compounds

The oxidation of organosulfur compounds is the most straightforward method for the preparation of sulfoxides and sulfones, important as commodity chemicals or pharmaceuticals. Noyori and co-workers reported an oxidative process using sodium tungstate dihydrate as catalyst, 30% aqueous H₂O₂ as oxidant, and Q+HSO^4- as PTC, besides phenylphosphonic acid as a promoter of the biphasic oxidation, which converts several aromatic and aliphatic organosulfur compounds into the corresponding sulfoxides and sulfones without organic solvents. With this method diphenyl sulfide is converted into diphenyl sulfone with 96% yield. The authors studied others substrates, the aliphatic sulfides being more reactive than the aromatic counterparts. Moreover, the substrates with allyl groups or with primary or secondary alcohols are oxidized to the corresponding sulfones, the allylic and the alcohol groups being unaffected.


 

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There is one kind of tungsten silicone-based shielding product, that made with tungsten, iron, bismuth or mixtures of these metals. The advantages of tungsten silicone-based shielding are base on the good performance of tungsten, iron, and bismuth. Tungsten silicone-based material offers the ability to put the shielding as close as possible to the source. In situations where space is limited, tungsten allows for the highest attenuation with the lowest shielding thickness and excellent radiation absorption. Iron provides a much less expensive option when space is not as limited. Bismuth is the middle ground offering excellent attenuation at a wide range of gamma energies. Tungsten silicone-based shielding can be formed into almost any size or shape.

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Tungsten-filled polymers, such as nylons, urethanes and thermoplastic elastomers. Tungsten loadings range from 65% to 80% by weight to meet radiopacity requirements. Tungsten-filled polymers shields against radiation but far more safely than lead. Tungsten-filled polymers has the same density as lead, meaning it can shield radiation at the same level as lead. Manufacturing with lead is currently banned in Europe, and is on track to be banned in the U.S. Use of tungsten in plastics dates back several years when efforts accelerated to replace lead for radiation-shielding applications.

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e) Oxidation of imines

The oxidation of N-alkyl imines with 30% hydrogen peroxide, in the presence of sodium tungstate dihydrate, led to the highly selective synthesis of oxaziridines in acetonitrile under mild conditions.


 

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Tungsten dichloro dioxide (WO2Cl2) alias is pizza grass and the system number is: CAS number: 13520-76-8, MDL number: MFCD00054136, EINECS number: 236-862-1, PubChem ID: 24863944.Synthesis of tungsten dichloro oxide as follows:
1. Preparing the reaction tube, the reaction tube has prepared a number of pure oxyhalide by chemical transmission technology.
2. Insert the tungsten oxide9.274g and tungsten chloride 7.931g in a long 15cm, 24cm diameter rigid tube, which was mixed.
3. Adding a slight excess of 1mg of WCI6 in a glass tube.
4. Connect one end of the glass tube is placed frozen in liquid nitrogen and the other end connected to a vacuum system to react together.
5. About 20h after completion of the reaction with a yellow sheet tungsten dichloro dioxide (Ⅵ) crystal in growth area. Then placed tube in reverse hot temperature gradient (200 ℃ / temperature) immediately which allow the more volatile impurities (such as WCl6 and WOCl4) condensed into the empty end of the reaction tube.

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Tungsten dichloro dioxide is a chemical product of the formula WO2Cl2. The physical properties of tungsten dichloro oxide as follows: molecular weight is 286.7448, the melting point is 266 ℃, morphology is a thin sheet of yellow crystals and solubility: soluble in water, ammonia and alkali, insoluble in ethanol.

Tungsten dichloro dioxide is stable at room temperature and atmospheric pressure, but to avoid the wet oxide or an alkali metal. Storage methods are: room sealed, in a cool, airy stored under dry inert gas. WO2Cl2 is very sensitive to atmosphere’s moisture oxide and therefore the reaction tube must be opened in dry nitrogen atmosphere and stored in a vacuum or dry inert gas. WO2Cl2 has acutely toxic, must be equipped with safety measures in the case of operations, to avoid direct contact, or will cause any harm. What’s more it is also pollute water, so do not making undiluted product or large WO2Cl2’s product to reach ground water, water course or sewage system, without the relevant units allow material shall not be released to the environment.

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