Tantalum oxychlorides

Alternate methods a) Methods IV and V for the preparation of NbClg can be applied to TaClg in exactly the same manner. Since (in contrast to NbOCla) no tantalum oxychloride is formed, the products are fairly pure. 

Fluorides. Tantalum pentafluoride [7783-71-3] TaF, (mp = 96.8° C, bp = 229.5° C) is used in petrochemistry as an isomerization and alkalation catalyst. In addition, the fluoride can be utilized as a fluorination catalyst for the production of fluorinated hydrocarbons. The pentafluoride is produced by the direct fluorination of tantalum metal or by reacting anhydrous hydrogen fluoride with the corresponding pentoxide or oxychloride in the presence of a suitable dehydrating agent (71). The ability of TaF to act as a fluoride ion acceptor in anhydrous HF has been used in the preparation of salts of the AsH, H S, and PH ions (72). The oxyfluorides TaOF [20263-47-2] and Ta02F [13597-27-8] do not find any industrial appHcation. 

A more recent process, which avoids the difficulties associated with Marignac s method, is based on the solubility of niobium pentoxide and the comparative insolubility of tantalum pentoxide in a mixture of equal volumes of selenium oxychloride, SeOCI8, and concentrated sulphuric acid.8 The tantalum pentoxide is left in the residue, and hydrolysis of the extract after dilution yields niobic acid. 

In this method metal chlorides or oxychlorides are made to react with gaseous hydrocarbons in the vicinity of a localized heat source (1400-2100 K). Clearly, the reaction is thermodynamically favorable (Tables 3 and 4). The method was first used by Van Arkel in 1923 with an incandescent tungsten filament to make carbides of tantalum and zirconium [40]. Although the reaction variables have been studied extensively, problems remain with control of the process and with low productivity. Application to catalyst synthesis has been moderate [41],... 

CARBON OXYCHLORIDE (75-44-5) Poisonous gas. Decomposes slowly with water, producing hydrochloric acid and carbon monoxide. Reacts violently with strong oxidizers, anhydrous ammonia, isopropanol, chemically active metals, silicon tetrahydride, sodium. Forms shock-sensitive material with potassium. Incompatible with tcrt-butylazidoformate, sodium azide. Attacks most metals in moist conditions however, it may not affect monel, tantalum, or glass-lined equipment. Note Sodium hydroxide or anhydrous ammonia has been used to neutralize this gas. 

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... 

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