Frémy's salt is a
chemical compound with the formula (K4[ON(SO3)22), sometimes written as (K2[NO(SO3)2]). It is 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)22−.
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]
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]
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]
^
abWehrli PA, Pigott F (1972). "Oxidation with the nitrosodisulfonate radical. I. Preparation and use of sodium nitrosodisulfonate: trimethyl-p-benzoquinone". Organic Syntheses. 52: 83.
doi:
10.15227/orgsyn.052.0083.
^Wertz JE, Bolton JR (1972). Electron Spin Resonance: Elementary Theory and Practical Applications. New York: McGraw-Hill.
ISBN978-0-07-069454-5. See page 463 for information on intensity measurements and page 86 for an EPR spectrum of Frémy's salt.
^Colacicchi S, Carnicelli V, Gualtieri G, Di Giulio A (2000). "EPR study of Frémy's salt nitroxide reduction by ascorbic acid; influence of bulk pH values". Res. Chem. Intermed. 26 (9): 885–896.
doi:
10.1163/156856700X00372.
S2CID98775951.
^Zielonka J, Zhao H, Xu Y, Kalyanaraman B (October 2005). "Mechanistic similarities between oxidation of hydroethidine by Frémy's salt and superoxide: stopped-flow optical and EPR studies". Free Radical Biology & Medicine. 39 (7): 853–863.
doi:
10.1016/j.freeradbiomed.2005.05.001.
PMID16140206.
^Islam I, Skibo EB, Dorr RT, Alberts DS (October 1991). "Structure-activity studies of antitumor agents based on pyrrolo[1,2-a]benzimidazoles: new reductive alkylating DNA cleaving agents". Journal of Medicinal Chemistry. 34 (10): 2954–2961.
doi:
10.1021/jm00114a003.
PMID1920349.
^Xue W, Warshawsky D, Rance M, Jayasimhulu K (2002). "A metabolic activation mechanism of 7H-dibenzo[c,g]carbozole via o-quinone. Part 1: synthesis of 7H-dibenzo[c,g]carbozole-3,4-dione and reactions with nucleophiles". Polycyclic Aromatic Compounds. 22 (3–4): 295–300.
doi:
10.1080/10406630290026957.
S2CID95507636.
^Wilchek M, Miron T (March 2015). "Mussel-inspired new approach for polymerization and cross-linking of peptides and proteins containing tyrosines by Frémy's salt oxidation". Bioconjugate Chemistry. 26 (3): 502–510.
doi:
10.1021/bc5006152.
PMID25692389.
^Liu ZL, Han ZX, Chen P, Liu YC (November 1990). "Stopped-flow ESR study on the reactivity of vitamin E, vitamin C and its lipophilic derivatives towards Frémy's salt in micellar systems". Chemistry and Physics of Lipids. 56 (1): 73–80.
doi:
10.1016/0009-3084(90)90090-E.
PMID1965427.