Vanadium chloride anhydrous

Electronic Grade Silicon (EGS). As the first step in the production of electronic grade silicon (EGS), an impure grade of silicon is pulverized and reacted with anhydrous hydrochloric acid, to yield primarily tricholorosilane, HSiClg. This reaction is carried out in afluidizedbed at approximately 300°C in the presence of a catalyst. At the same time, the impurities in the starter impure silicon reactto form their respective chlorides. These chlorides are liquid at room temperature with the exception of vanadium dichloride and iron dichloride, which are soluble in HSiCl3 at the low concentration prevailing. Purification is accomplished by fractional distillation. 

Preparation of Anhydrous Dioxovanadium Nitrate (VO2NO3). Prepare 7-10 ml of liquid nitrogen(IV) oxide (see p. 141). Mix the nitrogen(IV) oxide with 5-7 cm of dry acetonitrile in a test tube (see Fig. 92a). Add 0.3-0.5 g of metallic vanadium preliminarily crushed in a porcelain mortar to this mixture. Close the test tube with a stopper provided with a calcium chloride tube containing phosphoric anhydride. 

During the period 1965-1975 the chemistry of the 1,2-dithiolene complexes of the transition metals was the subject of considerable study.86,87,91-98 However, during this period of great activity few complexes of the early transition metals were reported aside from those of vanadium. The problem had much to do with synthetic procedures, since reaction of, say, the anhydrous metal chlorides with the dithiolene or its sodium salt did not prove successful. However, the use of metal dialkylamides99 did result in clean reactions (e.g. equation 21). 

Thermochemical Considerations.—The heats of formation of the three anhydrous chlorides of vanadium have been determined by combustion in a bomb calorimeter and are found to be as follows —6... 

Calcium Metavanadate, Ca(V03)2.3H20, gives rise to bright yellow needles when a solution of ammonium metavanadate is boiled with calcium chloride solution and precipitated with alcohol.6 The tetra-hydrate, Ca(V03)2.4H20, is prepared by allowing a mixture of potassium metavanadate and calcium chloride to evaporate for several days.7 Anhydrous calcium metavanadate is a white, porous substance, which is unaffected by strong heating, but is readily decomposed by acids to yield vanadium pentoxide.8 It is much more soluble in water than strontium metavanadate. 

Thirty milliliters of vanadium (IV) chloride (0.28 mol) is introduced into a 50-ml. round-bottomed flask to which is sealed a small water-cooled condenser (Fig. 13). This operation is carried out in a dry box since the tetrachloride must be protected from contact with moist air. The top of the condenser is sealed to a tube which is connected to a trap cooled with ice. The trap is joined by rubber tubing to a tube containing anhydrous calcium chloride. Dry carbon dioxide is passed through an inlet... 

Low-valent metal salts have been used to bring about reductive cleavage of oximes. Corey and Rich-man used chromium(II) acetate to convert O-acetyl ketoximes into imines, which were hydrolyzed to ketones. " Aqueous titanium(III) chloride and vanadium(II) salts also reduce oximes again, the imines are usually hydrolyzed in situ, but some hindered imines, such as compound (37), are isolable." A method of preventing hydrolysis is to carry out the reduction in anhydrous conditions in the presence of an acylating agent. The products of such reactions, when applied to oximes of enolizable ketones, are en-amides. For example, these ketoximes are converted into A/-formylenamines when heated in acetonitrile with anhydrous titanium(III) acetate and acetic formic anhydride cyclohexanone oxime gives the en-amide (38 97% Scheme 22)." This type of reduction has been used by Barton and coworkers to prepare enamides from steroidal oximes. They reported that the reaction could be performed by acetic... 

For this synthesis anhydrous vanadium (III) chloride is required. This may be purchased, or prepared either from vanadium(V) oxide via vanadium(IV) chloride or by refluxing vanadium(V) oxide with excess hexachloropropene for several days and filtering the purple solid produced. 

The cyclopentadienyl sodium solution, obtained as just described, is treated with 25 g. (0.16 mol) of anhydrous vanadium(III) chloride. An exothermic reaction occurs and the solution becomes a dark purple. 

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