Perrhenate, ammonium

Checked ry Tuno-oh ino WANO,t Jacob KiEiNBERc.f George M. Adams, and Burl E. BryantJ 

Rhenium is commonly separated as the heptasulfide and isolated as potassiiun perrhenate, a substance which is sparingly soluble in water. The ammonium salt, which is desirable for the preparation of pure rhenium and rhenium compounds, is less readily obtained than is the potassium salt because of the pronounced solubility of ammonium perrhenate in water. Ammonium perrhenate can be obtained readily by neutralizing a solution of perrhenic acid with ammonia. 

A perrhenic acid solution is obtained from 10.0 g. (0.036 mol) of potassium perrhenate by the method of Watt and Thompson. The perrhenic acid solution is concentrated 

Ammonium hexahalorhenate(IV) compounds can readily be made by substituting ammonium perrhenate for the potassium salt in procedures such as those for the synthesis of potassium hexabromorhenate(IV) and potassium hexachlororhenate (I V).  

Druce Rhenium, p. 40, Cambridge University Press, London, 

Checked by Tuno-ch inq WANo,t Jacob KcEiNBERG.t George M. Adams,t and Burl E. BryantJ 

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Salts of perrhenic acid may be obtained in acid—base reactions, and may include the tetrahedral ReO anion or the octahedral anion ReO , eg, in Ba (ReOg)2 [13598-09-9], Ammonium perrhenate and perrhenic acid, as well as rhenium metal, are sold by the primary suppHers of this element. 

The products from cyclization reactions of 4-substituted phthalonitriles are called 2,3-tetrasub-stituted or 2,9,16,23-tetrasubstituted phthalocyanines (see p 724). A mixture of four different structural isomers is obtained (see p 736). Cyclization of 4-/c//-butylphthalonitrile (7) in the presence of ammonium perrhenate(VII) at 290 C affords the nitridorhenium(V) phthalocvanine 8. 

Ammonium peroxodisulfate, 13 408 Ammonium perrhenate, 21 688, 690 rhenium content in, 21 695 specifications for, 21 693t Ammonium phosphates, 2 684, 708 ... 

Rhenium is attacked by neither hydrochloric acid nor by cold sulfuric or hydrofluoric acid. However, oxidizing acids, such as nitric acid or hot sulfuric acid, vigorously react with the metal forming perrhenic acid, HRe04. The metal is oxidized by hydrogen peroxide in ammoniacal solution forming ammonium perrhenate, NH4Re04. 

Two methods are in common use for the production of metallic rhenium. The first of these involves a direct reduction of commercial potassium perrhenate (procedure A) and yields a product that usually contains a small amount of alkali but is pure enough for most preparative purposes. The second method (procedure B) is slightly more complicated in that a preliminary precipitation of rhenium heptasulfide is followed by conversion to ammonium perrhenate which is subsequently reduced to the metal.1,2 Metallic rhenium so produced is usually purer than that prepared by direct reduction of the potassium salt. 

Ammonium perrhenate is appreciably volatile consequently its decomposition must be carried out at as low a temperature as possible, f University of Wisconsin, Madison, Wis. t University of Illinois, Urbana, 111. 

Metallic rhenium, prepared by the reduction of either potassium perrhenate (see synthesis 60A) or ammonium perrhenate (see synthesis 60B), is placed in a previously ignited porcelain boat and inserted in a pyrex combustion tube of the type shown in Fig. 31. All air in the train is displaced with nitrogen that has been passed through alkaline pyrogallol A and sulfuric acid B. 

Acetic acid-acetic anhydride, 85 Alkali azides, 79 Alkaline earth azides, 79 Alumino-oxalates, 36 Amalgams, 5 concentration of, 17 preparation of, 6 rare earth metal, 15 Ammonium nitrourethane, 69 Ammonium perrhenate, 177 Antimony oxyiodide, 105 Antimony triiodide, 104 Aquopentammino cobalti bromide, 187, 188... 

R. J. C. Brown and R. M. Lynden-Bell, J. Phys. Condens. Matter, 6, 9903 (1994). A Computer Simulation Study of the Disorder in Ammonium Perrhenate. 

Ammonium perrhenate, mixture of, with ammonium nitrate for preparation of rhenium, 1 177, 178... 

We pioneered the use a noncoherent IR radiation for a formation of the metal -carbon film on a surface of porous inorganic support. In this research the film was obtained from a mixture PAN and ammonium perrhenate solutions in dimethylformamide on the surface of the porous stainless steel. 

The catalytic activity of membrane catalyst, obtained by IR-pyrolysis of PAN and ammonium perrhenate, was studied in the flow membrane reactor in a model reaction of cyclohexane dehydrogenation at the temperatures from 500 to 700 K. 

Prepared by reduction of ammonium perrhenate with Li-EtNfy. 

In the case of functionalized olefins, i.e, where Ri and/or R2 are not simple alkyl chains, it is better to use a Re207/Al203 catalyst. Such catalysts can be prepared by pore-volume impregnation with an aqueous solution of ammonium perrhenate. It is observed that the turnover frequency, i.e. the activity per Re atom, increases considerably with Re207 loading up to monolayer coverage of the alumina surface (about 18 wt.% Re207 for an alumina of 200 m2/g). A theory... 

Several refractory borides, such as ReB2 and Re23Be, can be prepared from heating the elements at ca. 1200 °C. ReSi2 is a semiconductor. The nitride ResN is formed from ammonia and ammonium perrhenate, but Re does not form a nitride with N2. MP3, prepared from the elements in the presence of iodine, contain M and have both P-P and M-M bonds. Rc2P, ResQ , and ReP are also known (Q = P or As)." Carbon dissolves in Re up to 5 mol%. 

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