- Di-tert-alkyl nitroxyl radicals. Synthesis, physical properties and applications as inhibitors of vinyl polmerization at elevated temperatures
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Stable di-tert-alkylnitroxyl radicals, tert-butyl-tert-pentylnitroxyl (4a), di-tert-pentylnitroxyl (4b) and tert-octyl-tert-pentylnitroxyl (4c), the homologs of di-tert-butylnitroxyl (1), were synthesized from tert-alkyl amines 7a-c via the 3-tert-alkylamino-3-methyl-1-butynes 8a-c. Oxidation of 8a,b with hydrogen peroxide lead to relatively unstable N-tert-alkyl-N-(1,1-dimethyl-prop-2-ynyl)nitroxyl radicals 15a,b. The thermal stability, vapor pressure data, ultraviolet, visible and electron paramagnetic resonance spectra of 4a-c were recorded. The radicals were explored as potential inhibitors of unwanted alkene polymerization reactions at elevated temperatures, in comparison with the aliphatic di-tert-butyl nitroxyl (1), the alicyclic nitroxyl radicals 2,2,6,6-tetramethylpiperidin-1-oxyl (2) and 4-hydroxy-2,2,6,6-tetramethyl-piperidin-1-oxyl (3), some commercial polymerization inhibitors, such as diethyl-hydroxylamine (Pennstop, 16), ammonium salt of N-hydroxy-N-nitrosobenzenamine (Cupferron, 17), bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate (Tinuvin 770, 18), and the well-known spin traps 2-methyl-2-nitrosopropane (19) and tert-butylhydroxylamine (20).
- Sosnovsky, George,Jawdosiuk, Mikolaj,Clumpner, J. Michael
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p. 109 - 126
(2007/10/03)
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- REACTIONS OF NITROGEN NUCLEOPHILES WITH 1-BROMOALLENES: REGIOSELECTIVE SYNTHESIS OF PROPARGYLAMINES
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The results of a study on the reactivity of 3-alkyl- and 3,3-dialkyl-1-bromo-1,2-dienes 2 towards nitrogen nucleophiles, such as aqueous ammonia, lithium amide, aliphatic and aromatic amines allowed us to propose new methods for the synthesis of propargylamines, 1, with an available acetylenic hydrogen.The regio- and the stereoselectivity of these reactions are examined and possible mechanisms are discussed.
- Geri, Roberto,Polizzi, Carmela,Lardicci, Luciano,Caporusso, Anna Maria
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p. 241 - 248
(2007/10/02)
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