2,2,6,6-tetramethyl-1 -piperidinyloxy TEMPO

Unprotected or partially protected glycosides cannot generally be oxidized to uronic acid by the above-described methods. However, for unprotected carbohydrates milder and more selective oxidants have been developed that take advantage of the primary alcohol function being more sterically accessible. An important reagent for this transformation is 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) which is a shelf-stable and commercially available nitrosyl radical... 

Selective oxidation of primary hydroxyl groups can be achieved with 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) and hypobromite or hypochlorite at pH 10.5-11. A 98% selectivity was observed for starch, and selectivity of over 90% for inulin [113]. 

Nitroxide Mediated Living Radical Polymerization. Another controlled radical polymerization developed in recent years is stable free radical mediated polymerization (SFRP), also called as nitroxide mediated radical polymerization (NMP) (78,131). This type polymerization can be reahzed through reversible deactivation of growing radicals by stable radical such as 2,2,6,6-tetramethyl-piperidinyloxy (TEMPO). 

Developments in the synthesis and characterization of stable silylenes (RiSi ) open a new route for the generation of silyl radicals. For example, dialkylsilylene 2 is monomeric and stable at 0 °C, whereas N-heterocyclic silylene 3 is stable at room temperature under anaerobic conditions. The reactions of silylene 3 with a variety of free radicals have been studied by product characterization, EPR spectroscopy, and DFT calculations (Reaction 3). EPR studies have shown the formation of several radical adducts 4, which represent a new type of neutral silyl radicals stabilized by delocalization. The products obtained by addition of 2,2,6,6-tetramethyl-l-piperidinyloxy (TEMPO) to silylenes 2 and 3 has been studied in some detail. ... 

In 1993, Georges and coworkers [23,202,203] first succeeded in the synthesis of poly(St) with a narrow molecular weight distribution through the free-radical polymerization process of St. The polymerization was carried out in the presence of BPO and 2,2,6,6-tetramethyl-l-piperidinyloxy (TEMPO) ... 

Copper(II) complex 1 selectively catalyzes the oxidation of primary alcohols to aldehydes in high yields by atmospheric oxygen in the presence of 2,2,6,6-tetramethyl-l-piperidinyloxy (TEMPO).This procedure does not require an... 

The direct oxidation of hydroxyls on inulin allows the potential introduction of carbonyl and carboxyl groups, altering the properties of the polysaccharide and opening additional commercial applications (Bragd et al., 2004). The primary hydroxyl in the C-6 position on the fructofuranoside subunits can be selectively oxidized using 2,2,6,6-tetramethyl-l-piperidinyloxy (TEMPO). This forms a stable radical that can be oxidized by hypobromite, or similar reagent, to give a nitrosonium... 

Inhibition by radical traps or radical anion scavengers has been extensively used in providing evidence for the mechanism with both aliphatic and aromatic substrates. The most commonly employed inhibitors are compounds that add irreversibly to radicals butylnitroxide (DTBN), 2,2,6,6-tetramethyl-l-piperidinyloxy (TEMPO), galvinoxyl, etc.] and good reversible electron acceptors such as dinitrobenzenes (DNB) which intercept the radical anions38. 

Living radical dispersion polymerization is a promising way to expand the design and scope of functional polymer colloids to a wider range of other monomers. The 2,2,6,6-tetramethyl-l-piperidinyloxy (TEMPO)-mediated living radical dispersion polymerization of styrene has been carried out in presence of PS-h-P(PP-aZt-E) in decane at 135 °C [95] or PVP in alcohol-water at 130 °C [96] in order to produce microspheres with a very broad size distribution, consisting of relatively low molecular weight polystyrene (M =10 ) with M /Mn=l.l. 

Tetramethyl-l-piperidinyloxy (TEMPO), a nitroxy radical (Figure 10.3), is an effective catalyst for the oxidation of primary alcohols in the presence of secondary alcohols [9]. Iwabuchi and co-workers reported excellent catalytic activity of 2-azaadamantane-N-oxyl (1-Me-AZADO) towards a variety of alcohols. Oxidation of secondary alcohols was effected by means of 1 mol% of 1-Me-AZADO (Equation 10.4) [10]. 

Several classes of organometallic species react with nitroxides to provide N-alkoxyamine products. Most commonly used is the commercially available nitro-xide 2,2,6,6-tetramethyl-l-piperidinyloxy (TEMPO, 1). This has been demonstrated for numerous species including R-Li, R-MgBr, R-TiX3, R-ZrX, R-CuCN-Li, R-Zn-I, R-Cu-CN-ZnI, and R-Sml2 [8]. These reactions generally require two equiv-... 

A typical procedure to prepare the sodium bisulfite adduct of 2-cyclohexylacetaldehyde is as follows. A 10-L reactor is charged with 2-cyclohexylethanol (350 g), CH2CI2 (1.37 L), and 2,2,6,6-tetramethyl-l-piperidinyloxy (TEMPO) (4.27 g) under inerted atmosphere. A solution of KBr (32.8... 

NMP is based on the concept of a dynamic equilibration between dormant alkoxyamines and propagating radicals as shown in eqn [55].The choice of the persistent radical is cmcial for controlled polymerization. While styrene can be easily moderated by 2,2,6,6-tetramethyl-l-piperidinyloxy (TEMPO), other monomers required the development of nitroxides that contain hydrogen atoms at the a-C. There are two different initiation methods for NMP. Conventional radical initiators (i.e., AIBN, BPO) in conjunction with a persistent radical were initially used to prepare polymers by NMP, but these systems were limited in the choice of monomer. Functionality could be incorporated via a functionalized initiator or a functionalized persistent radical. For example, Baumert and Mulhaupt prepared carboxylic acid-terminated polystyrene, poly(styrene-co-acrylonitrile), and polystyrene-b-poly (styrene-co-acrylonitrile) by the use of the functionalized initiator 4,4 -azobis(4-cyanopentanecarboxylic acid). The polymerization was controlled by the addition of 2,2,6,6-tetramethyl-l-piperidyloxyl radical, and polymers with... 

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