Tantalum trichloride

A hydrated tantalum sesquioxide, Taj03.a H20, is stated to be formed by the addition of caustic soda to solid tantalum trichloride (Buff and Thomas, Zeitsch. anorg. Ghent., 1925, 148, 3 Ber., 1922, 55, 1473). 

Tantalum Trichloride, TaCls, is prepared by reducing the pentachloride with aluminium in the presence of aluminium chloride and heating the product to between 350° and 400° C. It is a dark green substance which yields intensely green aqueous solutions without evolution of hydrogen. These solutions are fairly stable, and oxidise only slowly on being exposed to air the rate of oxidation is accelerated by the presence of alkali and checked by the addition of acids. 

TaCI3 TANTALUM TRICHLORIDE 1596 ThC1.94 THORIUM 1.94-CARBIDE 1644... 

TaCI3[g] TANTALUM TRICHLORIDE (GAS) 1597 fhCW THORIUM TETRACHLORIDE 1645... 

Addition of other nucleophiles or Lewis bases to neopentyltantalum complexes also generated alkylidene complexes, as shown in Scheme 13.2. Addition of slightly less than one molar equivalent of bis(neopentyl)zinc to tantalum pentachloride generated bis(neopentyl) tantalum trichloride, and addition of thalium cyclopentadienide to this intermediate generated the Cp-ligated tantalum alkylidene. Addition of dative ligands, such as THE, and monodentate or bidentate phosphines to the bis(neopentyl)tantalum complex generated the octahedral alkylidenes in Scheme 13.2. ... 

Another method of purifying niobium is by distillation of the anhydrous mixed chlorides (29). Niobium and tantalum pentachlorides boil within about 15°C of one another which makes control of the process difficult. Additionally, process materials must withstand the corrosion effects of the chloride. The system must be kept meticulously anhydrous and air-free to avoid plugging resulting from the formation of niobium oxide trichloride, NbOQ. Distillation has been used commercially in the past. 

Chlorination of ferroalloys (ferroniobium-tantalum) is a more economical and simple alternative [30]. The process is performed on a sodium chloride melt that contains iron trichloride, FeCU. Chlorine is passed through the melt yielding NaFeCl4, which interacts as a chlorination agent with the Fe-Nb-Ta alloy. Chlorination of ferroalloys allows for the production of pure tantalum and niobium pentachlorides, which are used further in the production of high purity oxides and other products. 

Fonetal. dialkylated a tantalum(aryloxo)(amido) trichloride with 2equiv. diethylzinc to furnish the corresponding diethyltantalum complex 25, as shown in Scheme 22.62... 

Undoubtedly, the best method for the production of pure anhydrous lanthanide trihalides involves direct reaction of the elements. However, suitable reaction vessels, of molybdenum, tungsten, or tantalum, have to be employed silica containers result in oxohalides (27). Trichlorides have been produced by reacting metal with chlorine (28), methyl chloride (28), or hydrogen chloride (28-31). Of the tribromides, only that of scandium has been prepared by direct reaction with bromine (32). The triiodides have been prepared by reacting the metal with iodine (27, 29, 31, 33-41) or with ammonium iodide (42). 

Mercury(II) /V-pcrchlory lbcnzylamidc. 3651 Monopotassium perchlorylamide, 3994 Nitrogen triiodide-silver amide, 4634 Nitrosylruthenium trichloride, 4144 Pentaamminedinitrogenruthenium(II) salts, 4596 Pentakis(dimethylamino)tantalum, 3384 Pentasilver diamidophosphate, 0046 Pentasilver orthodiamidophosphate, 0044 Plutonium nitride, 4726 Poly (dimercury immonium hydroxide), 4422... 

Silver difluoride, 0014 Silver fluoride, 0013 Sodium chloride, 4036 Sodium iodide, 4623 Tantalum pentachloride, 4185 Tellurium tetrabromide, 0296 Thallium, 4922 Tin(II) chloride, 4116 Tin(IV) chloride, 4174 Tin(II) fluoride, 4331 Titanium(II) chloride, 4117 Titanium dibromide, 0284 Titanium diiodide, 4630 Titanium tetrachloride, 4176 Titanium tetraiodide, 4638 Titanium trichloride, 4158... 

The above reaction is utilized in large-scale industrial production of methanol. Reaction with boron trichloride over a hot tungsten or tantalum filament yields boron and hydrogen chloride ... 

Terbium metal is obtained from its anhydrous trifluoride, TbFs, or trichloride, TbCls, by thermal reduction with calcium, carried out in a tantalum crucible. Terbium produced by such methods may contain traces of calcium and tantalum. High purity metal can be prepared by various methods such as vacuum remelting, distillation, amalgam formation, floating zone melting, and various chemical processes. 

Tantalum Tetrachloride, TaCl4.—The formation of a green substance the composition of which agreed with that of a tetrachloride was observed during the preparation of the trichloride, but from the data available it was impossible to deeide if it was a simple compound or a mixture of the pentachloride and the trichloride.4... 

Oxidizer, Poison, Corrosive SAFETY PROFILE Poisonous and corrosive. Very reactive, a powerful oxidizer. Explosive or violent reaction with organic materials, water, acetone, ammonium halides, antimony, antimony trichloride oxide, arsenic, benzene, boron, bromine, carbon, carbon monoxide, carbon tetrachloride, carbon tetraiodide, chloromethane, cobalt, ether, halogens, iodine, powdered molybdenum, niobium, 2-pentanone, phosphoms, potassium hexachloroplatinate, pyridine, silicon, silicone grease, sulfur, tantalum, tin dichloride, titanium, toluene, vanadium, uranium, uranium hexafluoride. 

One method of separating niobium from tantalum is to pass a gaseous mixture of niobium(V) chloride and tantalum(V) chloride over adjacent beds of calcium oxide and calcium fluoride the niobium emerges as volatile niobium(V) oxide trichloride whilst the tantalum is trapped in the CaO and CaFj beds. The reactions postulated to be responsible for trapping tantalum are [1984b] ... 

Perchloric acid Phosphomolybdic acid Phosphorus oxychloride Phosphorus pentachloride Phosphorus trichloride y-Picoline Polyphosphoric acid Potassium silicate Rhodium Selenium Selenium dioxide Silica gel Silver oxide (ous) Sodium borohydride Sodium silicate Strontium carbonate Sulfur dioxide Tantalum Tellurium Tetraisopropyl di (dioctylphosphito) titanate Titanocene dichloride Trichloromethylphosphonic acid Tristriphenylphosphine rhodium carbonyl hydride Tungsten carbide Vermiculite Ytterbium oxide Zinc chloride Zinc dust Zinc 2-ethylhexanoate Zirconium potassium hexafluoride... 

Chlorination of ferroniobium has been carried out by the U.K. Atomic Energy Authority first at the Culcheth Laboratories and later at Spring-fields, in a development plant with a capacity of about 1 tonne/annum. As with some other chlorination processes, the design and operation of plant for the reaction with chlorine itself is relatively easy, and a major proportion of the effort must be devoted to the production of the niobium pentachloride or trichloride in a pure state. In this case the problem is made particularly difficult by the presence of a high proportion of tantalum in the ferroniobium, an element which beairs a very close resemblance to niobium in its chemical properties. The physical properties of its compounds are also similar to the corresponding niobium compounds. 

The mixed chlorides from the chlorinator are maintained above 350°C before feeding to the main condensor at 30°C. This takes the form of three steel tubes in parallel, each 2 ft long by 2 in. diameter and fitted with simple scrapers operated through glands. The tubes lead to a 12 in. deep by 12 in. diameter chamber underneath, which collects the loose deposit of niobium and tantalum pentachlorides, ferric chloride and tungsten penta- and hexachlorides. The capacity of this condenser is about 23 kg of chlorides, i.e. a volume of about 8 1. A separate small trap, cooler than the main condenser, collects aluminium trichloride and titanium tetrachloride (b.p. 183 C and 136°C respectively). A series of cold traps and scrubbers is then used to free the tail gas from chlorine and trace quantities of chlorides carried over by entrainment, before release to atmosphere. 

Preferential reduction of niobium pentachloride to the trichloride by the excess of hydrogen still present is used in the next stage, to separate from tantalum pentachloride, which remains volatile, i.e. 

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