Typical physical and chemical properties
Catalog Number ACM2564832-4
Product Name TEMPO
CAS 2564-83-2
Synonyms TEMPO free radical; 2,2,6,6-Tetramethyl-1-piperidinyloxy, free radical; 2,2,6,6-Tetramethylpiperidinooxy; 2,2,6,6-Tetramethylpiperidine 1-oxyl
Description (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl or (2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl, commonly known as TEMPO, is a chemical compound with the formula (CH2)3(CMe2)2NO. This heterocyclic compound is a red-orange, sublimable solid. As a stable radical, it has applications in chemistry and biochemistry. TEMPO was discovered by Lebedev and Kazarnowskii in 1960. It is prepared by oxidation of 2,2,6,6-tetramethylpiperidine. TEMPO is widely used as a radical marker, as a structural probe for biological systems in conjunction with electron spin resonance spectroscopy, as a reagent in organic synthesis, and as a mediator in controlled radical polymerization. The stability of this radical is attributed to the resonance provided by non-bonding electrons on the nitrogen atom, which form a 2c3e (half-) bond between nitrogen and oxygen, and hyperconjugative ability. Additional stability arises from the steric protection provided by the four methyl groups adjacent to the nitroxyl group; however, the methyl groups prevent a double bond occurring between either carbon adjacent to nitrogen. The stability of the radical is also indicated by the weakness of the O–H bond in the hydrogenated derivative TEMPO–H. With an O–H bond dissociation energy of about 70kcal/mol, this bond is about 30% weaker than a typical O–H bond.
Molecular Weight 156.25
Molecular Formula C9H18NO
InChI InChI=1S/C9H18NO/c1-8(2)6-5-7-9(3,4)10(8)11/h5-7H2,1-4H3
Boiling Point 193°C
Melting Point 36-40ºC
Flash Point 67ºC
Purity 98%
Density 1 g/cm³
Solubility Soluble in all organic solvents. Insoluble in water.
Appearance Orange crystals or powder
Application Contact reaction oxidant for iodobenzene diacetyl to oxidize nerol to generate neral. In summary, copper/TEMPO is used for the contact reaction of the 1-alcohol to form an aldehyde.
Storage Store at 2-8°C, filled with argon
Complexity 136
Covalently-Bonded Unit Count 1
Defined Atom Stereocenter Count 0
Defined Bond Stereocenter Count 0
Exact Mass 156.138839198
Formal Charge 0
Heavy Atom Count 11
Hydrogen Bond Acceptor Count 1
Hydrogen Bond Donor Count 0
Isotope Atom Count 0
Monoisotopic Mass 156.138839198
Physical State Yellow to green powder
Rotatable Bond Count 0
Topological Polar Surface Area 4.2 Ų
Undefined Atom Stereocenter Count 0
Undefined Bond Stereocenter Count 0
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