Presentation on theme: "Phosphorus Hydrides in Radical Chemistry David Sharpe University of York."— Presentation transcript:
Phosphorus Hydrides in Radical Chemistry David Sharpe University of York
Outline of talk Introduction Phosphorus hydride chemistry Previous work Development of new phosphorus hydride reagents Radical reactions of phosphorus hydride reagents Chemistry of Organophosphorus adducts Oxidation chemistry Formation C=C and C-C bonds Conclusions Future Work
Introduction Ageing Poor selectivity Toxicity Disease Novel reactivity E.g. Anti-Markovnikov addition of HBr to alkenes Mild reaction conditions -OH and –NH functionalities do not need to be protected
Traditional radical reagents Bu 3 SnH Toxicity Difficult to remove tin by-products SmI 2 Difficult to prepare Toxicity Radioactive
Cleaning up radical chemistry We need to consider Recovery/disposal of waste Reaction conditions (i.e. solvents, temperature) Project aims To generate organophosphorus adducts by radical addition of phosphorus hydride reagents to alkenes. To use organophosphorus compounds in synthetically useful reactions.
Conclusions We have been able to add To both Electron-rich alkenes Electron-poor alkenes The resulting organophosphorus compounds undergo Alkylation Acylation HWE
Future Work Development of HWE chemistry of phosphinothioates Different aldehydes/ketones Different phosphinothioates Diphenylphosphine sulfide in other reactions Reduction of halides
Acknowledgments Dr A. F. Parsons Dr P. Taylor ICI Paints and E.P.S.R.C. for funding Members of the AFP group past and present. Gillian Allen Gregory Bar Nicola Chessum Nathalie Huther Chris Jessop Jaouad El Harfi Tom Hunt Jim Rawlinson Ruth Bingham Tony Wright No technicians were harmed during this project. Thank you for listening
Peroxydisulfates Extremely cheap (K 2 S 2 O 8, 100g, £8.40) Strong oxidising agents (E = 1.92 V, SO 4 2- /SO 4 - ) Half-life at 80 o C ~1 h Possible to make organosoluble peroxydisulfates
Advantages of radical chemistry Mild reaction conditions Low temperature Acid/base sensitive functionalities are unreactive Novel reactivity Anti-Markovnikow addition of HBr Umpolung chemistry Electrophilic radical Nucleophilic radicalElectrophile Nucleophile Radicals are uncharged.But…. They have a polarity
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