Английская Википедия:Frémy's salt
Шаблон:Chembox Frémy's salt is a chemical compound with the formula (K4[ON(SO3)2]2), sometimes written as (K2[NO(SO3)2]). It a bright yellowish-brown solid, but its aqueous solutions are bright violet.[1][2] The related sodium salt, disodium nitrosodisulfonate (NDS, Na2ON(SO3)2, CAS 29554-37-8) is also referred to as Frémy's salt.[3]
Regardless of the cations, the salts are distinctive because aqueous solutions contain the radical [ON(SO3)2]2−.
Applications
Frémy's salt, being a long-lived free radical, is used as a standard in electron paramagnetic resonance (EPR) spectroscopy, e.g. for quantitation of radicals. Its intense EPR spectrum is dominated by three lines of equal intensity with a spacing of about 13 G (1.3 mT).[4][5][6]
The inorganic aminoxyl group is a persistent radical, akin to TEMPO.
It has been used in some oxidation reactions, such as for oxidation of some anilines and phenols[7][8][9][10][11] allowing polymerization and cross-linking of peptides and peptide-based hydrogels.[12][13]
It can also be used as a model for peroxyl radicals in studies that examine the antioxidant mechanism of action in a wide range of natural products.[14]
Preparation
Frémy's salt is prepared from hydroxylaminedisulfonic acid. Oxidation of the conjugate base gives the purple dianion:
- HON(SO3H)2 → [HON(SO3)2]2− + 2 H+
- 2 [HON(SO3)2]2− + PbO2 → 2 [ON(SO3)2]2− + PbO + H2O
The synthesis can be performed by combining nitrite and bisulfite to give the hydroxylaminedisulfonate. Oxidation is typically conducted at low-temperature, either chemically or by electrolysis.[3][2]
Other reactions:
- HNO2 + 2 Шаблон:Chem → Шаблон:Chem + H2O
- 3 Шаблон:Chem + Шаблон:Chem + H+ → 3 Шаблон:Chem + MnO2 + 2 H2O
- 2 Шаблон:Chem + 4 K+ → K4[ON(SO3)2]2
History
Frémy's salt was discovered in 1845 by Edmond Frémy (1814–1894).[15] Its use in organic synthesis was popularized by Hans Teuber, such that an oxidation using this salt is called the Teuber reaction.[9][10]
References
Further reading
- ↑ Шаблон:Greenwood&Earnshaw2nd
- ↑ 2,0 2,1 Шаблон:Cite web
- ↑ 3,0 3,1 Шаблон:Cite journal
- ↑ Шаблон:Cite book See page 463 for information on intensity measurements and page 86 for an EPR spectrum of Frémy's salt.
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ 9,0 9,1 Шаблон:Cite journalШаблон:Dead link
- ↑ 10,0 10,1 Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ See:
- Frémy, E. (1845) "Sur un nouvelle série d'acides formés d'oxygène, de soufre, d'hydrogène et de d'azote" (On a new series of acids formed from oxygen, sulfur, hydrogen, and nitrogen), Annales de Chimie et de Physique, 3rd series, 15 : 408-488. Frémy's salt appears on p. 447, where it's called "sulfazidate de potasse".
- Frémy, E. (1845) "Sur un nouvelle série d'acides formés d'oxygène, de soufre, d'hydrogène et de d'azote" (On a new series of acids formed from oxygen, sulfur, hydrogen, and nitrogen), Comptes rendus, 21 : 218–226. This is a condensed version of the article that appeared in Annales de Chimie et de Physique.
- "Séances académiques," L'Institut, no. 604, 23 July 1845, pp. 265–266.
- "Séances académiques," L'Institut, no. 619, 12 November 1845, pp. 393. Here a committee of the French Academy of Sciences reviewed Frémy's findings.
- Edward Divers and Tamemasa Haga (1900) "Identification and constitution of Frémy's sulphazotised salts of potassium," Шаблон:Webarchive Journal of the Chemical Society, Transactions, 77 : 440-446. doi:10.1039/CT9007700440 Here, correct formulae for Frémy's salts are presented. On p. 445 , the salt that Frémy called sulfazidate is identified as ON(SO3K)2.
