CAS 2564-83-2 TEMPO - Catalysts / Alfa Chemistry

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.

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

Molecular Weight

156.25

Molecular Formula

C9H18NO

Canonical SMILES

CC1(CCCC(N1[O])(C)C)C

InChI

InChI=1S/C9H18NO/c1-8(2)6-5-7-9(3,4)10(8)11/h5-7H2,1-4H3

InChI Key

QYTDEUPAUMOIOP-UHFFFAOYSA-N

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

Storage

Store at 2-8°C, filled with argon

Complexity

136

Covalently-Bonded Unit Count

Defined Atom Stereocenter Count

Defined Bond Stereocenter Count

EC Number

219-888-8

Exact Mass

156.138839198

Formal Charge

Heavy Atom Count

Isotope Atom Count

LogP

2.31290

MDL Number

MFCD00009599

Monoisotopic Mass

156.138839198

Physical State

Yellow to green powder

Rotatable Bond Count

Stability

Stable. Incompatible with strong acids, strong oxidizing agents. Refrigerate.

Topological Polar Surface Area

4.2 Å²

Undefined Atom Stereocenter Count

Undefined Bond Stereocenter Count