Examination of novel alkoxyamines has demonstrated the pivotal role that nitroxide plays in mediating "living" or controlled polymerization a wide range vinyl monomers. Surveying variety different alkoxyamine structures led to α-hydrido derivatives based on 2,2,5-trimethyl-4-phenyl-3-azahexane-3-oxy, 1, skeleton which were able control styrene, acrylate, acrylamide, and acrylonitrile For each monomer set, molecular weight could be from 1000 200 000 amu with polydispersities typically...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTetra-n-butylammonium oxone. Oxidations under anhydrous conditionsBarry M. Trost and Rebecca BraslauCite this: J. Org. Chem. 1988, 53, 3, 532–537Publication Date (Print):February 1, 1988Publication History Published online1 May 2002Published inissue 1 February 1988https://pubs.acs.org/doi/10.1021/jo00238a011https://doi.org/10.1021/jo00238a011research-articleACS PublicationsRequest reuse permissionsArticle Views2163Altmetric-Citations151LEARN ABOUT...

Quantum dot (QD) fluorescence is effectively quenched at low concentration by nitroxides bearing amine or carboxylic acid ligands. The association constants and quenching of CdSe QDs with these derivatized have been examined using electron paramagnetic resonance (EPR) spectroscopy. EPR spectra in the nonprotic solvent toluene are extremely sensitive to intermolecular intramolecular hydrogen bonding functionalized nitroxides. Fluorescence measurements show that QD luminescence nonlinear, a...

Copper‐free azide‐alkyne click chemistry is utilized to covalently modify polyvinyl chloride (PVC). Phthalate plasticizer mimics di(2‐ethylhexyl)‐1H‐triazole‐4,5 dicarboxylate (DEHT), di(n‐butyl)‐1H‐1,2,3‐triazole‐4,5‐dicarboxylate (DBT), and dimethyl‐1H‐triazole‐4,5‐dicarboxylate (DMT) are attached PVC. DEHT, DBT, DMT have similar chemical structures traditional plasticizers di(2‐ethylhexyl) phthalate (DEHP), di(n‐butyl) (DBP), dimethyl (DMP), but pose no danger of leaching from the polymer...

Abstract Nitroxides bearing an α‐hydrogen decompose upon heating in a bimolecular reaction. A new mechanism is proposed for the decomposition of t‐butylisopropylphenyl nitroxide (TIPNO) involving formation head‐to‐tail dimer, single electron transfer to form oxammonium salt, epimerization corresponding nitrone, and elimination conjugated oxime. This may provide insights into designing nitroxides use controlled polymerization. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Chem 44: 697–717, 2006

Suppression of mitochondrial production reactive oxygen species is a promising strategy against intrinsic apoptosis typical degenerative diseases. Stable nitroxide radicals such as 4-hydroxy-2,2,6,6-tetramethyl piperidine-1-oxyl (TEMPOL) and its analogs combine several important features, including recycleability, electron acceptance from respiratory complexes, superoxide dismutase mimicry, radical scavenging. Although successful in antioxidant protection, their effective concentrations are...

Polyvinyl Chloride (PVC) is among the most abundant plastics worldwide. Phthalates and other plasticizers—small molecules added to PVC impart flexibility—have raised numerous health concerns due their tendency migrate out of PVC, where they can be ingested or contaminate environment. Internal plasticization, in which a plasticizer covalently bound backbone, offers solution problem migration. This comprehensive review covers preparation internally plasticized literature. Strategies fall into...

Low-temperature methods for the preparation of monomeric initiators use in "living" free radical olefin polymerizations have been developed. Oxidative generating carbon radicals presence nitroxide traps such as TEMPO utilize PbO2 with benzylic, alkyl, or phenylhydrazines CuCl2 lithium enolates. Photolytic employ [Cp(CO)2Fe]2 a benzylic bromide, diphenyl disulfide styrene, di-tert-butyl peroxide ethers. The hyponitrite ethers generates at 50 °C that are trapped by TEMPO.

Polyvinyl chloride (PVC) is a problematic waste plastic with limited options for recycling or upcycling. Herein, we demonstrate preliminary results in breaking down the long carbon chains of PVC into oligomers and small organic molecules. First, treatment substoichiometric amount alkali base effects elimination HCl to form salt creates regions conjugated carbon-carbon double bonds, as determined by 1 H NMR UV-Vis spectroscopy. Olefin cross metathesis an added partner alkene then cleaves...

[reaction: see text] We report a new methodology for the synthesis of N-alkoxyamines, which can be used as initiators in "living" free radical polymerization. Silyl abstraction from alkyl halides allows N-alkoxyamines inaccessible by other methods.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHalogen regiochemistry and substituent stereochemistry determination in marine monoterpenes by carbon-13 NMRPhillip Crews, Steve Naylor, F. Joe Hanke, E. Rick Hogue, Ernest Kho, Rebecca BraslauCite this: J. Org. Chem. 1984, 49, 8, 1371–1377Publication Date (Print):April 1, 1984Publication History Published online1 May 2002Published inissue 1 April 1984https://doi.org/10.1021/jo00182a011RIGHTS & PERMISSIONSArticle Views262Altmetric-Citations36LEARN...

ABSTRACT Branched and linear nonmigratory internal plasticizers attached to PVC by a pendant triazole linkage were synthesized investigated. Copper‐free azide‐alkyne thermal cycloaddition was employed covalently bind triazole‐based phthalate mimics PVC. To systematically investigate the effect of plasticizer structure on glass transition temperature, several architectural motifs explored. Free volume theory considered when designing many these plasticizers: hexyl‐tethers utilized generate...

A new strategy involving the internal plasticization of poly(vinyl chloride) (PVC) is successfully achieved by copolymerization vinyl chloride (VC) and commercial available monomers such as n-butyl acrylate (n-BA) oligo(ethylene oxide) methyl ether (OEOA). To evaluate effect on glass transition temperatures (Tg) resulting PVC-co-POEOA, PVC-co-PBA PVC-co-PBA-co-POEOA copolymers, solvent, initiator, polymerization temperature VC/n-BA/OEOA ratios were systematically investigated. These...

The coupling reaction between a chiral C2-symmetric nitroxide, trans-2,5-dimethyl-2,5-diphenylpyrrolidin-1-oxyl (DPPO; 1), and series of stabilized secondary prochiral radicals was studied to determine the factors that affect stereoselectivity. Both steric electronic perturbations on selectivity by substituents radical were observed. effects temperature, solvent polarity, viscosity examined. High for reactions carried out in solvents low provides evidence formation an encounter complex path....

Differentiation between the two enantiotopic faces of prochiral carbon radicals by optically active nitroxyl is demonstrated in this novel approach to control stereochemistry. In first experiments, steroid radical shown Equation (a) gave selectivities up 92:8.

Abstract The eggs of the alcyonacean soft coral Lobophytum microlobulatum contain known cembranoid diterpene 3,4‐epoxynephthenol (9). This compound was not detected in colony from which were released, although decaryiol (10), is derived (9) by acid treatment, present and tissue. new acetate (11) a natural product coral. Several non‐cembranoid diterpenes based on eudesmane, germacrene elemene sesquiterpene skeletons isolated. Investigation chemistry two species afforded are prenylated...

Nitroxide-mediated "living" radical polymerization with bisalkoxyamine 2,5,5,8,8,11-hexamethyl-4,9-(1-phenylethoxy)-3,10-diphenyl-4,9-diazadodecane produces polymers of controlled length and narrow molecular weight distributions at temperatures ranging from 70 to 110 °C. Polymerizations were run successfully styrene (St), tert-butyl acrylate (tBA), dimethylacrylamide (DMA). EPR measurements the homolysis this monoalkoxyamine 2,2,5-trimethyl-3-(1-phenylethoxy)-4-phenyl-3-azahexane 85 105 °C...