Reactivity of Phosphorus-Centered Radicals Generated during the Photoreaction of Diphenylphosphinous Acid with 10-Methylacridinium Salt
摘要:
Diphenylphosphinous acid (1) reacts with 10-methylacridinium iodide (2a) in aqueous acetonitrile during irradiation by visible light under an argon atmosphere at 20 degrees C to afford diphenylphosphinic acid (3) and 10-methylacridan (4). The effects of the solvent and atmosphere and the effect of added iodide ion (I-) or iodine (I-2) on the product distribution show that the mechanism involves initial single-electron transfer (SET) from 1 to 2a in the photoexcited state, by which cation radical 1(+.) and dihydroacridinyl radical 2(.) are generated. Cation radical 1(+.) undergoes electrophilic reaction with water in the solvent, and the resulting phosphoranyl radical decomposes through SET to iodine atom (I-.) rather than undergoing beta-scission, eventually giving 3. Protonation to 2(.) followed by reduction by I- affords 4. These reaction sequences make up the catalytic I-./I- couple. The results are interpreted on the basis of reported redox potentials.
Flame retardant epoxy prepregs, laminates, and printed wiring boards of enhanced thermal stability
申请人:Ranken F. Paul
公开号:US20050075024A1
公开(公告)日:2005-04-07
Boehmite (alumina monohydrate) when used with a typical epoxy resin advanced with phosphorus makes it possible to improve thermal stability and to increase the ignition time of laminates formed from prepregs made using this fortified resin. Such laminates have exceptionally high thermal stability and showed similar longer times to ignition as compared to corresponding resins in which alumina trihydrate was used.
FLAME RETARDANT EPOXY PREPREGS, LAMINATES, AND PRINTED WIRING BOARDS OF ENHANCED THERMAL STABILITY
申请人:ALBEMARLE CORPORATION
公开号:EP1670860A1
公开(公告)日:2006-06-21
[EN] FLAME RETARDANT EPOXY PREPREGS, LAMINATES, AND PRINTED WIRING BOARDS OF ENHANCED THERMAL STABILITY<br/>[FR] PREIMPREGNES EN RESINE EPOXYDE IGNIFUGES, LAMINES, ET CARTES DE CIRCUITS IMPRIMES PRESENTANT UNE STABILITE THERMIQUE AMELIOREE
申请人:ALBEMARLE CORP
公开号:WO2005040277A1
公开(公告)日:2005-05-06
Boehmite (alumina monohydrate) when used with a typical epoxy resin advanced with phosphorus makes it possible to improve thermal stability and to increase the ignition time of laminates formed from prepregs made using this fortified resin. Such laminates have exceptionally high thermal stability and showed similar longer times to ignition as compared to corresponding resins in which alumina trihydrate was used.
Reactivity of Phosphorus-Centered Radicals Generated during the Photoreaction of Diphenylphosphinous Acid with 10-Methylacridinium Salt
Diphenylphosphinous acid (1) reacts with 10-methylacridinium iodide (2a) in aqueous acetonitrile during irradiation by visible light under an argon atmosphere at 20 degrees C to afford diphenylphosphinic acid (3) and 10-methylacridan (4). The effects of the solvent and atmosphere and the effect of added iodide ion (I-) or iodine (I-2) on the product distribution show that the mechanism involves initial single-electron transfer (SET) from 1 to 2a in the photoexcited state, by which cation radical 1(+.) and dihydroacridinyl radical 2(.) are generated. Cation radical 1(+.) undergoes electrophilic reaction with water in the solvent, and the resulting phosphoranyl radical decomposes through SET to iodine atom (I-.) rather than undergoing beta-scission, eventually giving 3. Protonation to 2(.) followed by reduction by I- affords 4. These reaction sequences make up the catalytic I-./I- couple. The results are interpreted on the basis of reported redox potentials.