Potassium hexachloromolybdate

Potassium hexachloromolybdate, 3, 1230 Potassium hexacyanoferrate discovery, 1, 3 Potassium ions biology, 6, 559 selective binding biology, 6, 551... 

The electroextraction process for molybdenum involves the use of its oxides, carbides or sulfides as soluble anodes in a potassium chloride-potassium hexachloromolybdate (K3MoCl6) molten electrolyte. An inert atmosphere electrolytic cell, with a provision for semicontinuous electrolysis, is used for this purpose. The process operation consists of the following steps. 

Preparation of Potassium Hexachloromolybdate(III). Perform the experiment in a fume cupboard ) Dissolve 50 g of molybdic anhydride in 250 ml of concentrated hydrochloric acid. Spill the molyb-denum(Vl) oxide into the beaker in small portions as it dissolves during 6 hours. If the solution is turbid, filter it through a glass filter (prepare the solution beforehand). 

Potassium hexachloro-ji-1,4-buta-diene-diplatinate(II), 6 216 Potassium hexachloromolybdate-(III), 4 97, 99... 

Further precipitation occurs when the alcohol mixes with the filtrate from the precipitation of the pentachloroaquo salt. This precipitate is a mixture of potassium hexachlo-romolybdate(III) and potassium pentachloraquomolyb-date(III) and is removed by filtration. The filtrate is then concentrated at 70° to 80 ml. by use of the water pump, and more of the mixture of the two salts is precipitated (3.8 g.). This mixture is filtered and washed with 12 N hydrochloric acid and with alcohol, the latter causing the second salt, potassium hexachloromolybdate(III), to precipitate in the filtrate in fairly pure form. The yield is 10.0 g. (15.6%). Anal. Calcd. for K3[MoCl6] Mo, 22.5 Cl, 50.0. Found Mo, 22.3 Cl, 50.6. The impurity here is probably potassium chloride. 

Trichloro (tripyridine) molybdenum (III) has been prepared by the reaction of molybdenum(III) chloride with pyridine at 270° for 5 hours in a sealed tube. The preparation described below using potassium hexachloromolybdate-(III) as starting material is carried out at a lower temperature, requires less time, and involves no special apparatus. 

To 50 ml. (about 0.6 mol) of reagent-grade pyridine in a 125-ml. round-bottomed flask there is added 8.5 g. (0.02 mol) of potassium hexachloromolybdate(III). The mixture is heated with a Glas Col mantle, or microburner, and refluxed at 115 to 117° for 3 hours using a conventional water-cooled reflux column. At the end of the reaction time, upon cooling, a yellow precipitate suspended in a dark brown solution is observed. 

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