2,2,6,6-tetramethylpiperidinyloxyl

Structural formula
General
Surname	2,2,6,6-tetramethylpiperidinyloxyl
other names	TEMPO; 2,2,6,6-tetramethylpiperidin-1-oxyl;
Molecular formula	C 9 H 18 NO
Brief description	reddish, crystalline solid
External identifiers / databases
EC number	219-888-8
ECHA InfoCard	100,018,081
PubChem	2724126
Wikidata	Q209120
properties
Molar mass	156.25 g mol −1
Physical state	firmly
density	0.91 g cm −3
Melting point	39-40 ° C
boiling point	≈175 ° C (decomposition)
Vapor pressure	0.4 h Pa (20 ° C)
solubility	little in water (9.7 g l −1 at 20 ° C)
safety instructions
GHS labeling of hazardous substances danger
H and P phrases	H: 314
	P: 280-305 + 351 + 338-310
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

2,2,6,6-Tetramethylpiperidinyloxyl ( TEMPO ) is a stabilized radical that can be used as an oxidizing agent . Although it is not thermodynamically stable, its comparatively high persistence is due to substituents that influence the lifetime through steric effects . The substituents are in the vicinity of the radical electron, so that it has an average lifetime of one minute in an oxygen-free solution.

use

Crystals from TEMPO.

TEMPO is used in nitroxide-mediated polymerization (NMP). This is a controlled radical polymerization (CRP) and allows high molar masses of the polymers, as well as the synthesis of block copolymers . It can also be used as a spin probe in electron spin resonance experiments.

It is also used as an oxidation catalyst together with a suitable co-oxidizer (often sodium hypochlorite ) in organic chemistry ( Anelli oxidation ).

Web links

Organic Chemistry: TEMPO

Individual evidence

↑ ^a ^b ^c ^d ^e ^f data sheet 2,2,6,6-tetramethylpiperidin-1-oxyl (free radical) (PDF) from Merck , accessed on March 13, 2017.
↑ ^a ^b TEMPO data sheet at Sigma-Aldrich , accessed on March 13, 2017 ( PDF ).

↑ Pier Lucio Anelli, Carlo Biffi, Fernando Montanari, Silvio Quici: Fast and selective oxidation of primary alcohols to aldehydes or to carboxylic acids and of secondary alcohols to ketones mediated by oxoammonium salts under two-phase conditions. In: The Journal of Organic Chemistry. 52, 1987, p. 2559, doi : 10.1021 / jo00388a038 .

[Merck-1] ↑ ^a ^b ^c ^d ^e ^f data sheet 2,2,6,6-tetramethylpiperidin-1-oxyl (free radical) (PDF) from Merck , accessed on March 13, 2017.

[Sigma-2] TEMPO data sheet at Sigma-Aldrich , accessed on March 13, 2017 ( PDF ).

[DOI10.1021/jo00388a038-3] Pier Lucio Anelli, Carlo Biffi, Fernando Montanari, Silvio Quici: Fast and selective oxidation of primary alcohols to aldehydes or to carboxylic acids and of secondary alcohols to ketones mediated by oxoammonium salts under two-phase conditions. In: The Journal of Organic Chemistry. 52, 1987, p. 2559, doi : 10.1021 / jo00388a038 .