Fremy's salt
Encyclopedia
Frémy's salt, discovered in 1845 by Edmond Frémy
(1814–1894), is a chemical compound
and a strong oxidizing agent. The formal name is disodium nitrosodisulfonate or Na2NO(SO3)2, but the expression "Frémy's salt" refers equally well to potassium nitrosodisulfonate, also known as potassium peroxylamine disulfonate. Frémy’s salt (chemical formula: (K4[ON(SO3)2]2) is commonly known as potassium nitrodisulfonate radical dianion (NDS) and potassium peroxylamine disulfonate (K2[NO(SO3)2]). NDS, a product of disassociation of Frémy’s salt, is commonly used to examine the mechanism of oxidation and hydroxylation. Frémy’s salt is a commercially accessible dimer of NDS, it is also a relatively stable source of water-soluble nitroxyl radical that is used as an electronic spin resonance (ESR) standard for g-value determination and radical quantization it is also mainly used in oxidation reactions.
like TEMPO
. It is especially useful in oxidations of aniline
s and phenol
s to quinone
s.
Fremy's salt, being a long-lived free radical, is a useful reagent for electron paramagnetic resonance
(EPR) work. The molecule gives an intense EPR spectrum dominated by three lines of equal intensity with a spacing of about 13 G (= 1.3 mT). For more details, see Wertz and Bolton (1972).
Fremy’s salt is commonly used in oxidation of aromatic amine and phenol structures. 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. Also are used in the synthesis of metabolites which are found to later bind with DNA. One of its few biological applications involves evaluation of radical scavenging activity and EPR kinetic studies. It is also a useful tool in understanding the reduction mechanism by ascorbic acid (AscH2).
, sodium bicarbonate
, and sulfur dioxide
to disodium hydroxylaminedisulfonate and carbon dioxide
followed by one-electron oxidation by electrolysis
in a basic solution. This reaction must be carried at 5˚C or lower with constant stirring.
Other Reactions:
In the solid phase, potassium nitrodisulfonate has a bright yellowish-brown color, but it is bright violet in aqueous solutions. EPR measurements can be made to ensure the purity and paramagnetism of the compound.
Edmond Fremy
Edmond Frémy was a French chemist. He is perhaps best known today for Frémy's salt, a strong oxidizing agent which he discovered in 1845...
(1814–1894), is a chemical compound
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
and a strong oxidizing agent. The formal name is disodium nitrosodisulfonate or Na2NO(SO3)2, but the expression "Frémy's salt" refers equally well to potassium nitrosodisulfonate, also known as potassium peroxylamine disulfonate. Frémy’s salt (chemical formula: (K4[ON(SO3)2]2) is commonly known as potassium nitrodisulfonate radical dianion (NDS) and potassium peroxylamine disulfonate (K2[NO(SO3)2]). NDS, a product of disassociation of Frémy’s salt, is commonly used to examine the mechanism of oxidation and hydroxylation. Frémy’s salt is a commercially accessible dimer of NDS, it is also a relatively stable source of water-soluble nitroxyl radical that is used as an electronic spin resonance (ESR) standard for g-value determination and radical quantization it is also mainly used in oxidation reactions.
Applications
The nitroso compound is a persistent radicalRadical (chemistry)
Radicals are atoms, molecules, or ions with unpaired electrons on an open shell configuration. Free radicals may have positive, negative, or zero charge...
like TEMPO
TEMPO
oxyl, or oxidanyl or TEMPO is a chemical compound with the formula 32NO . This heterocycle is a red-orange, sublimable solid. As a stable radical, it has applications throughout chemistry and biochemistry. TEMPO was discovered by Lebedev and Kazarnowskii in 1960...
. It is especially useful in oxidations of aniline
Aniline
Aniline, phenylamine or aminobenzene is an organic compound with the formula C6H5NH2. Consisting of a phenyl group attached to an amino group, aniline is the prototypical aromatic amine. Being a precursor to many industrial chemicals, its main use is in the manufacture of precursors to polyurethane...
s and phenol
Phenol
Phenol, also known as carbolic acid, phenic acid, is an organic compound with the chemical formula C6H5OH. It is a white crystalline solid. The molecule consists of a phenyl , bonded to a hydroxyl group. It is produced on a large scale as a precursor to many materials and useful compounds...
s to quinone
Quinone
A quinone is a class of organic compounds that are formally "derived from aromatic compounds [such as benzene or naphthalene] by conversion of an even number of –CH= groups into –C– groups with any necessary rearrangement of double bonds," resulting in "a fully conjugated cyclic dione structure."...
s.
Fremy's salt, being a long-lived free radical, is a useful reagent for electron paramagnetic resonance
Electron paramagnetic resonance
Electron paramagnetic resonance or electron spin resonance spectroscopyis a technique for studying chemical species that have one or more unpaired electrons, such as organic and inorganic free radicals or inorganic complexes possessing a transition metal ion...
(EPR) work. The molecule gives an intense EPR spectrum dominated by three lines of equal intensity with a spacing of about 13 G (= 1.3 mT). For more details, see Wertz and Bolton (1972).
Fremy’s salt is commonly used in oxidation of aromatic amine and phenol structures. 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. Also are used in the synthesis of metabolites which are found to later bind with DNA. One of its few biological applications involves evaluation of radical scavenging activity and EPR kinetic studies. It is also a useful tool in understanding the reduction mechanism by ascorbic acid (AscH2).
Preparation
Fremy's salt is commercially available. It can be prepared by the addition of sodium nitriteSodium nitrite
Sodium nitrite is the inorganic compound with the chemical formula NaNO2. It is a white to slight yellowish crystalline powder that is very soluble in water and is hygroscopic...
, sodium bicarbonate
Sodium bicarbonate
Sodium bicarbonate or sodium hydrogen carbonate is the chemical compound with the formula Na HCO3. Sodium bicarbonate is a white solid that is crystalline but often appears as a fine powder. It has a slightly salty, alkaline taste resembling that of washing soda . The natural mineral form is...
, and sulfur dioxide
Sulfur dioxide
Sulfur dioxide is the chemical compound with the formula . It is released by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide unless the sulfur compounds are removed before burning the fuel...
to disodium hydroxylaminedisulfonate and carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
followed by one-electron oxidation by electrolysis
Electrolysis
In chemistry and manufacturing, electrolysis is a method of using a direct electric current to drive an otherwise non-spontaneous chemical reaction...
in a basic solution. This reaction must be carried at 5˚C or lower with constant stirring.
Other Reactions:
- HNO2 + 2 HSO3− → HON(SO3)22− + H2O
- 3 HON(SO3)22− + MnO4− + H+ → 3 ON(SO3)22− + MnO2(s) + 2 H2O
- 2 ON(SO3)22− + 4 K+ → K4[ON(SO3)2]2(s)
In the solid phase, potassium nitrodisulfonate has a bright yellowish-brown color, but it is bright violet in aqueous solutions. EPR measurements can be made to ensure the purity and paramagnetism of the compound.