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

A 1-L, three-necked, round-bottomed flask equipped with a mechanical stirrer and two 100-mL addition funnels is charged with 4-methoxyphenethyl alcohol (If) (6.09 g, 40 mmol), TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy free radical) (0.436 g, 2.8 mmol), 200 mL of acetonitrile, and 150 mL of... 

The first workable capping agents for controlled radical polymerization were discovered by Rizzardo et al. [77, 78] who used nitroxides. The nitroxide reacts reversibly with radical chain ends but itself does not initiate the monomer. They called their new system Stable Free Radical Polymerization (SFRP). Scheme 32a depicts an example of SFRP using TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy). SFRP was developed independently by Georges at Xerox for the synthesis of styrene block polymer as dispersing agents [79]. 

SCM = shell cross-linked micelle SEM = scanning electron microscopy TEM = transmission electron microsopy TEMPO = 2,2,6,6-tetramethyl-1 -piperidinyloxy... 

A 1-liter reaction vessel was charged with 425 ml of styrene, maleic anhydride (100.2 g), and 2,2,6,6-tetramethyl-l-piperidinyloxy (0.0205 moles) and then treated dropwise with a mixture of 72 ml of styrene and 2,2,6,6-tetramethyl-1 -piperidinyloxy (0.0782 moles). The reaction was heated to 135°C for 45 minutes and cooled, and the mixture was dissolved in 500 ml of THE The polymer was precipitated in 3 liter of hexane, and 125.3 g solid product were isolated having a M of 3523 daltons and a polydispersity of 1.48. 

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]. 

Sun, Y., Wan, D., and Huang, J. (2001). Preparation of a copolymer of methyl methacrylate and 2-(dimethylamino)ethyl methacrylate with pendant 4-benzyloxy-2,2,6,6-tetramethyl-1-piperidinyloxy and its initiation of the graft polymerization of styrene by a controlled radical mechanism. J. Polym. Sci., Part A Polym. Chem., 39(5) 604-612. 

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