Diethylphosphono-dimethylpropyl nitroxide

Some improvements occurred by changing to nitroxides with a hydrogen on at least one of the a-carbons of the piperidine ring, in contrast to TEMPO, which has no hydrogens on a-carbons. However, the major breakthrough came by using sterically hindered alicyclic nitroxides with a hydrogen on one of the a-carbons. f-Butyl 2-methyl-1-phenylpropyl nitroxide (LVIII) and f-butyl l-diethylphosphono-2,2-dimethylpropyl nitroxide (LIX) are examples of... 

Di- and triblock polymers have been prepared by nitric oxide mediated polymerization using t-butyl l-diethylphosphono-2,2-dimethylpropyl nitroxide. Materials prepared from this process are useful as paint thickeners and viscosity index improvers in paint. 

A steel resin kettle was charged with t-butyl l-diethylphosphono-2,2-dimethylpropyl nitroxide (30.0 mmol) and methyl acrylate (6.97 mol) and then heated to 110°C for 3 hours, at which point the reaction had reached 50% conversion. The reaction mixture was cooled to ambient temperature and the M determined to be 12,600 daltons. In a... 

The nitric oxide mediated polymerization agent t-butyl 1-diethylphosphono-2,2-dimethylpropyl nitroxide, (I), was prepared according to the method of Gillet [1] as illustrated below ... 

Gnanou et al. reported the first successful homopolymerization of nBA in 1997 [70, 72,155] using a new nitroxide, N-ferf-butyl-AT-[l-diethylphosphono-(2,2-dimethylpropyl)] nitroxide (DEPN, Fig. 10). This nitroxide not only afforded faster polymerization rates at lower temperatures for the polymerization of St, but also allowed the controlled polymerization of nBA [73,156]. Further investigation showed that the success of the system lay in changing the equilibrium between the dormant chain and active species to favor the formation of a higher concentration of active species and therefore required the addition of free DEPN for full control [73] via the persistent radical effect [56]. Gnanou et al. also demonstrated that N-ferf-butyl- [1-phenyl-(2-methylpropyl)] nitroxide (BPPN, Fig. 12) could be used to moderate the polymerization of St, resulting in polymers with Mw/Mn<1.10 [156]. 

Fig. 12. Structures of N-tert-butyl-N- [l-diethylphosphono-(2,2-dimethylpropyl)] nitroxide (DEPN) and N-tert-butyl- [1 -phenyl-(2-methylpropyl)] nitroxide (BPPN) [155,156]...

It was shown that p-hydrogen-containing nitroxides promote the controlled polymerization of not only styrenic monomers but alkyl acrylates and dienes as well. Taking this into account, a novel ttifimcdonal alkoxyamine (Scheme 28, 7) based on N-t Tt-butyl-1 -diethylphosphono-2,2-dimethylpropyl nitroxide (Scheme 28, 8) was developed for the synthesis of 3-arm PS and poly(n-butyl acrylate) (PnBuA) stars along with (PnBuA-b-PS)3 star-block copolymers. ... 

NMP can be achieved in either of two ways (1) by adding a stable nitroxyl radical to the polymerization reaction initiated by traditional initiators (peroxides or azo compounds) to generate an alkoxyamine in situ, or (2) by preparing an alkoxyamine to be used as the initiator. Two widely stndied examples of stable nitroxyl radicals are 2,2,6,6-tetramethylpiperidinyl-l-oxyl [2564-83-2] (4, TEMPO) or 4-substitnted derivatives thereof and N-tert-bntyl-iV-[l-(diethylphosphono)-2,2-dimethylpropyl]nitroxide [188526-94-5] (5) (165-172). 

Acrylates can be polymerized using NMP when the proper nitroxide is employed. A(-fert-butyl-A(-(l-diethylphosphono-2,2-dimethylpropyl)nitroxide and N-ferf-butyl-A(-(2-methyl-l-phenyl-propyl)nitroxide were proven to be capable of controlling the polymerization of butylacrylate. 

Bon and co-workers were the first to publish a successfiil attempt toward TEMPO-mediated LRP in emulsion (109). This first work was far from optimal, since it only worked in seeded emulsion polymerization, and temperatures above 100°C were required to obtain a dynamic equilibrium between dormant and active species. NMP improved quite significantly with respect to its applicability in emulsion pol5unerization when the above-mentioned developments led to polymerization temperatures below 100°C. Notable in this respect was the work by Charleux and co-workers, who employed)V-tcrt-butyl-iV-(l-diethylphosphono-2,2-dimethylpropyl)nitroxide as the mediating nitroxide for the LRP of styrene and butyl acrylate in emulsion (110,111). 

Monomer conversion, evolution of molecular weight, reduced viscosity, and rate constants were assessed in Reference [65] in the case of the NMP of BA using A-tertiobutyl-1 -diethylphosphono-2,2-dimethylpropyl nitroxide (SGI). The reactions were carried out using both monocomponent (alkoxyamines with or without free SGI) and bicomponent (AlBN+free SGI) initiators. 

McHale R, Aldabbagh F, Zetterlund PB (2007) The role of excess nitroxide in the SGI (A-tert-butyl-A-[l-diethylphosphono-(2,2-dimethylpropyl)] nitroxide)-mediated polymerization of methyl methacrylate. J Polym Sci Part A Polym Chem 45 2194-2203... 

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