TEMPO

Description

TEMPO, like DABCO, the Molecule of the Week for August 29, 2022, is one of those molecules best known by its acronym. TEMPO’s full name is 2,2,6,6-tetramethyl-1-piperidinyloxy.
TEMPO is also unusual in that it is a stable free radical. Because of its unpaired electron, its color is a bright red-orange, in contrast to similar molecular structures, which do not absorb light in the visible region.
TEMPO was first synthesized in 1959 by USSR chemists O. L. Lebedev and S. N. Kazarnovskii. They oxidized 2,2,6,6-tetramethylpiperidine1 with hydrogen peroxide in the presence of pertungstate ion (WO42–). The authors called the resulting product an “intermediate”; it is not clear whether they realized that it was a free radical. Three years later, another Soviet researcher, A. V. Il’yasov, published data on the effect of solvents on the electron paramagnetic resonance2 (EPR) spectra of some stable free radicals, including TEMPO, so its status had been established by then.
TEMPO has multiple uses in organic chemistry: as a catalyst in oxidation reactions and radical-mediated polymerizations and as an EPR marker or probe in chemical and biochemical systems. In a recent example, Abudureheman Wusiman and co-workers at Xingjiang Normal University (Urumqi, China) used it to promote the mono- and bisimidation of tertiary anilines. The purpose of the reaction was to create a straightforward route to symmetric and unsymmetric N-Mannich bases3 under mild conditions.
1. CAS Reg. No. 768-66-1. 2. Also known as electron spin resonance (ESR). 3. A Mannich base is a β-amino ketone; an N-Mannich base has a nitrogen atom in place of the intermediate carbon atom, e.g., R2NCH2NHC(O)R.

The Uses of TEMPO

TEMPO(2,2,6,6-Tetramethylpiperidinooxy) is a stable radical prepared through the oxidation of 2,2,6,6-tetramethylpiperidine. TEMPO has a wide range of applications including use as a free radical scavenger, a reagent in organic synthe sis and as a structural probe in electron spin resonance spectroscopy. TEMPO can also be used as a mediator in free radical polymerization.

What are the applications of Application

TEMPO is a catalyst employed in the oxidation of primary alcohols to aldehydes with NaOCl