Perrhenic acid

Structural formula
General
Surname	Perrhenic acid
other names	Hydrogen perrhenate; Hydrogen tetraoxorhenate;
Molecular formula	HReO 4
Brief description	colorless to pale yellowish liquid
External identifiers / databases
EC number	237-380-4
ECHA InfoCard	100,033,968
PubChem	83718
ChemSpider	21106462
Wikidata	Q2710669
properties
Molar mass	251.21 g mol −1
Physical state	liquid (solution in water)
density	2.16 g cm −3 (25 ° C); 4.87 g cm −3 ;
Vapor pressure	23 hPa (20 ° C)
pK s value	−1.25
solubility	miscible with water
safety instructions
GHS labeling of hazardous substances danger
H and P phrases	H: 314
	P: 280-305 + 351 + 338-310
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Perrhenic acid is an inorganic chemical compound from the group of acids . It is only available in an aqueous solution. As solid perrhenic Dirheniumdihydratoheptoxid Re is ₂ O ₇ (OH ₂ ) ₂ , respectively.

Extraction and presentation

An aqueous perrhenic acid solution can be obtained by reacting rhenium with hydrogen peroxide .

{\ displaystyle \ mathrm {2 \ Re + 7 \ H_ {2} O_ {2} \ longrightarrow 2 \ HReO_ {4} +6 \ H_ {2} O}}

It is also possible to display it by dissolving rhenium (VII) oxide in water.

{\ displaystyle \ mathrm {Re_ {2} O_ {7} + H_ {2} O \ longrightarrow 2 \ HReO_ {4}}}

The solutions can only be used up to a concentration of max. 70 percent by weight of HReO _{4 are} evaporated, above that HReO ₄ evaporates .

Solid perrhenic acid can be obtained from an aqueous, as concentrated as possible, perrhenic acid solution by removing excess water in the desiccator using phosphorus pentoxide or magnesium perchlorate .

properties

Perrhenic acid cannot be represented as a pure substance and only exists as a colorless to slightly yellowish solution. Dirhenium dihydratoheptoxide is a pale yellowish, extremely hygroscopic solid. It is soluble in nitromethane and decomposes at 65 ° C with volatilization of HReO ₄ . It has a monoclinic crystal structure with the space group P 2 ₁ / m (space group no. 11) and the lattice parameters a = 882 pm, b = 889 pm, c = 503 pm and β = 112.0 °, with O ₃ Re- O-ReO ₃ (OH ₂ ) ₂ molecules. Template: room group / 11

use

Perrhenic acid is used to produce highly conductive and superconducting synthetic metals.

Individual evidence

↑ ^a ^b ^c ^d data sheet Perrhenic acid, 75-80% aq. Soln. at AlfaAesar, accessed on August 2, 2013 ( PDF )(JavaScript required) .
↑ ^a ^b ^c ^d ^e data sheet Perrhenic acid solution, 75-80 wt.% In H from Sigma-Aldrich , accessed on August 2, 2013 ( PDF ).
↑ ^a ^b ^c ^d ^e ^f Georg Brauer (Ed.) U. a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume III, Ferdinand Enke, Stuttgart 1981, ISBN 3-432-87823-0 , p. 1632.
↑ Entry on Perrhenate. In: Römpp Online . Georg Thieme Verlag, accessed on September 13, 2018.
↑ H. Beyer, O. Glemser, B. Krebs, G. Wagner: The structure of dirhenium dihydratoheptoxide Re2O7 (OH2) 2. - A new type of water binding in an aquoxide -. In: Journal of Inorganic and General Chemistry. 376, 1970, p. 87, doi : 10.1002 / zaac.19703760111 .

[Alfa-1] ta sheet Perrhenic acid, 75-80% aq. Soln. at AlfaAesar, accessed on August 2, 2013 ( PDF )(JavaScript required) .

[Sigma-2] ↑ ^a ^b ^c ^d ^e data sheet Perrhenic acid solution, 75-80 wt.% In H from Sigma-Aldrich , accessed on August 2, 2013 ( PDF ).

[brauer-3] ↑ ^a ^b ^c ^d ^e ^f Georg Brauer (Ed.) U. a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume III, Ferdinand Enke, Stuttgart 1981, ISBN 3-432-87823-0 , p. 1632.

[4] Entry on Perrhenate. In: Römpp Online . Georg Thieme Verlag, accessed on September 13, 2018.

[DOI10.1002/zaac.19703760111-5] H. Beyer, O. Glemser, B. Krebs, G. Wagner: The structure of dirhenium dihydratoheptoxide Re2O7 (OH2) 2. - A new type of water binding in an aquoxide -. In: Journal of Inorganic and General Chemistry. 376, 1970, p. 87, doi : 10.1002 / zaac.19703760111 .