Vanadium oxytrichloride

Most catalysts for solution processes are either completely soluble or pseudo-homogeneous all their catalyst components are introduced into the reactor as Hquids but produce soHd catalysts when combined. The early Du Pont process employed a three-component catalyst consisting of titanium tetrachloride, vanadium oxytrichloride, and triisobutjlalurninum (80,81), whereas Dow used a mixture of titanium tetrachloride and triisobutylalurninum modified with ammonia (86,87). Because processes are intrinsically suitable for the use of soluble catalysts, they were the first to accommodate highly active metallocene catalysts. Other suitable catalyst systems include heterogeneous catalysts (such as chromium-based catalysts) as well as supported and unsupported Ziegler catalysts (88—90). 

The second type of solution polymerization concept uses mixtures of supercritical ethylene and molten PE as the medium for ethylene polymerization. Some reactors previously used for free-radical ethylene polymerization in supercritical ethylene at high pressure (see Olefin POLYMERS,LOW DENSITY polyethylene) were converted for the catalytic synthesis of LLDPE. Both stirred and tubular autoclaves operating at 30—200 MPa (4,500—30,000 psig) and 170—350°C can also be used for this purpose. Residence times in these reactors are short, from 1 to 5 minutes. Three types of catalysts are used in these processes. The first type includes pseudo-homogeneous Ziegler catalysts. In this case, all catalyst components are introduced into a reactor as hquids or solutions but form soHd catalysts when combined in the reactor. Examples of such catalysts include titanium tetrachloride as well as its mixtures with vanadium oxytrichloride and a trialkyl aluminum compound (53,54). The second type of catalysts are soHd Ziegler catalysts (55). Both of these catalysts produce compositionaHy nonuniform LLDPE resins. Exxon Chemical Company uses a third type of catalysts, metallocene catalysts, in a similar solution process to produce uniformly branched ethylene copolymers with 1-butene and 1-hexene called Exact resins (56). 

Pentoxide when heated with chlorine gas at 500°C in the presence of carbon forms vanadium oxytrichloride ... 

Urea Peroxide Urea Peroxide Hexamethylenetetramine Hexamethylenetetramine Antimony Trioxide Valeraldehyde Valeraldehyde Valeraldehyde Vinyl Acetate Vanadium Pentoxide Vanadyl Sulfate Vanadium Oxytrichloride Vanadium Pentoxide Vanadium Pentoxide Vanadium Oxytrichloride Vanadyl Sulfate Vanadyl Sulfate Vanadium Oxytrichloride Captan... 

The isolation of vanadium can be effected on a very small scale, suitable as a lecture experiment, by passing an electric current through a platinum wire filament immersed in vanadium oxytrichloride, VOCl3, either iti vacuo or in an atmosphere of hydrogen.10 The metal is obtained as a smooth, silver-grey deposit. 

Vanadyl salts are salts of tetravalent vanadium, and contain the divalent [VO]- radical. Many vanadium compounds are known which appear to contain a [VO] group, but the vanadium is either trivalent or pentavalent. Throughout this book the term vanadyl is restricted to compounds of tetravalent vanadium, that is, to salts of the oxide V02. Hence, for example, the compound VOCI3, which contains pentavalent vanadium, is called vanadium oxytrichloride, and not by the more usual but less logical name vanadyl chloride. ... 

It can also be prepared by the reduction of vanadium oxytrichloride, VOCl3, in hydrogen at a red heat. It is a flaky, brown, crystalline substance density at 16° C., 2-824 soluble with difficulty in water but readily soluble in nitric acid.4... 

Vanadium Oxytrichloride, VOCl3, commonly known as vanadyl chloride, is the easiest to prepare of all the halogen or oxyhalogen compounds of vanadium. It distils over as a yellow liquid when vanadium pentoxide is strongly heated, or when vanadiun trioxide is gently heated, in a current of chlorine. Addition of charcoal accelerates the reactions 9... 

Halogenation in the presence of sulphur, or by means of sulphur halides, is also available. When chlorine is conducted into a mixture of vanadium pentoxide and sulphur, or when powdered vanadium pentoxide is treated with sulphur monochloride vapours, an immediate reaction sets in, with formation of vanadium oxytrichloride.2 A quantitative yield of this compound is also obtained when vanadium trichloride is heated in oxygen at 500° to 600° C.3... 

With more water, it passes into solution dilute solutions, which are brownish-yellow or red, according to the concentration, evolve chlorine and become blue on standing, undergoing reduction to the tetravalent state. On evaporation to dryness, aU the chlorine is evolved and the residue consists of the. pentoxide. Vanadium oxytrichloride is also soluble in ether and alcohol. It dissolves chlorine, bromine, iodine, yellow phosphorus, and sulphur, and is miscible with various liquid hydrocarbons and chlorinated hydrocarbons its use as an industrial solvent has therefore been suggested. ... 

The heat of formation of vanadium oxytrichloride is given by the equation ... 

Chemically pure vanadium pentoxide is alternatively prepared by precipitating insoluble mercurous vanadate, HgV03, from a neutral solution of a vanadate, and distilling off the mercury, or by ignition of vanadium salts of volatile acids, for example, vanadium oxytrichloride, VOCl3. The oxide also results from the oxidation of any of the lower oxides, or by the electrolysis of a solution of sodium vanadate or copper vanadate, using a divided cell the last method yields a product of 98 per cent, purity.2... 

By addition of mineral acids to solutions of vanadates, or by the hydrolysis of vanadium oxytrichloride, a reddish-brown, gelatinous precipitate of hydrated vanadium pentoxide is obtained. This is very... 

The corresponding bromine compounds are very comparable, but attempts to prepare corresponding iodo-derivatives were unsuccessful owing to the insolubility of niobic acid in hydriodic acid. Double compounds of vanadium oxytrichloride with pyridine, and tantalum oxytrichloride with pyridine and quinoline, have also been prepared. 

He found that with ordinary commercial red phosphorus with 98 per cent, phosphorus, there dissolved 0-056 and 0-108 per cent, of phosphorus in respectively 10 and 42 hrs., and with a finely-divided sample 0-092 and 0-116 percent, phosphorus in 10 and 20 hrs. respectively. R. Schenck found that 100 grms. of phosphorus tribromide dissolved 0-2601 grm. of scarlet phosphorus at 172°, and 0-3634 grm. at 184°. E. Baudrimont showed that yellow phosphorus does not attack phosphoryl bromide at the b.p. L. Rosenstein found that soln. of arsenates, and arsenic, antimony, or bismuth salts are not reduced by boiling with red phosphorus but W. Finkelstein found that a nitrobenzene soln. of arsenic trichloride is reduced by yellow phosphorus and arsenic is deposited. 0. Ruff observed that phosphorus reacts with antimony trichloride in the presence of a little aluminium chloride. F. E. Brown and J. E. Snyder observed that vanadium oxytrichloride is without action on red or white phosphorus. 

The product is colored red by the presence of vanadium tetrachloride and contains considerable dissolved chlorine. These impurities may be removed by fractional distillation followed by a distillation from metallic sodium. The last few milliliters of vanadium oxytrichloride should not be removed from the sodium by a direct flame, as superheating often causes an explosion. A fractionating udder is convenient for collecting the product without exposing it to the moisture in the air. The side tube should be connected to a drying tube. Yield 70 g. (87 per cent of theory) boiling point 124.5 to 125.5° at 744 mm. 

Vanadium oxytrichloride is a lemon-yellow liquid. Its boiling point is 124.5°C. at 736 mm. and 127.16°C. at 760 mm. It remains liquid at —77°. The vapor pressure at —77° is 4.1 mm. at 0°, 21 mm. and at 85°C., 270 mm. Its density in grams per milliliter is 1.854 at 0° and 1.811 at 32°C. At ordinary temperatures, it neither dissolves nor reacts with carbon, hydrogen, nitrogen, oxygen, silicon, tellurium, or metals except the alkali metals and antimony. The reactions with the alkali metals are explosive at characteristic temperatures, varying from 30°C. for cesium to 180°C. for sodium (lithium not determined). Small... 

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