Potassium nitrosodisulfonate

Structural formula
General
Surname	Potassium nitrosodisulfonate
other names	Fremy's salt
Molecular formula	K 2 [ON (SO 3 ) 2 ]
External identifiers / databases
EC number	238-219-0
ECHA InfoCard	100,034,729
PubChem	3032624
Wikidata	Q412650
properties
Molar mass	268.32 g mol −1
Physical state	firmly
safety instructions
H and P phrases	H: 260-302-312-332
	P: 223-231 + 232-280-370 + 378-422
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Potassium nitrosodisulfonate (also Fremy's salt , K ₂ [ON (SO ₃ ) ₂ ]) is the potassium salt of nitrosodisulfonic acid, which is not known in the free state . It was discovered in 1845 by Edmond Frémy (1814-1894).

properties

The orange-yellow colored crystals of potassium nitrosodisulfonate dissolve in water with a purple color. In the crystal the anion is dimeric ; in aqueous solution it dissociates into two radical anions (more precisely aminoxyl radicals). Potassium nitrosodisulfonate is a strong oxidizing agent that can be used, for example, in organic chemistry to convert phenols into quinones .

presentation

Nitrosodisulfonates are oxidation products of hydroxylamine- N , N- disulfonic acid, which is also not known in the free state . Potassium nitrosodisulfonate is obtained from the synthesis of this acid and its oxidation. Thereto is added an ice-cooled aqueous solution of sodium nitrite and sodium hydrogen sulfite with acetic acid , to give the corresponding hydroxylamine N , N disulfonate forms:

{\ displaystyle \ mathrm {HNO_ {2} +2 \ HSO_ {3} ^ {-} \ longrightarrow HON (SO_ {3}) _ {2} ^ {2 -} + H_ {2} O}}

This is oxidized in an ammoniacal environment with potassium permanganate to nitrosodisulfonate:

{\ displaystyle \ mathrm {3 \ HON (SO_ {3}) _ {2} ^ {2 -} + \ MnO_ {4} ^ {-} \ longrightarrow}}

{\ displaystyle \ mathrm {3 \ [\ cdot ON (SO_ {3}) _ {2}] ^ {2 -} + \ MnO_ {2} + \ OH ^ {-} + \ H_ {2} O}}

After filtration of the precipitated manganese dioxide , adding potassium chloride to the violet solution and cooling, Fremy's salt is obtained as orange-yellow crystals.

Individual evidence

↑ ^a ^b Data sheet Potassium nitrosodisulfonate from Sigma-Aldrich , accessed on April 7, 2011 ( PDF ).
↑ G. Brauer (Ed.), Handbook of Preparative Inorganic Chemistry 2nd ed., Vol. 1, Academic Press 1963, pp. 504-6.

Web links

Data sheet for a 50 to 75% mixture with water and methanol from Acros, accessed on 26 February 2010 .

[Sigma-1] Data sheet Potassium nitrosodisulfonate from Sigma-Aldrich , accessed on April 7, 2011 ( PDF ).

[2] G. Brauer (Ed.), Handbook of Preparative Inorganic Chemistry 2nd ed., Vol. 1, Academic Press 1963, pp. 504-6.