Synthesis of Phosphonium Salts-Phosphine Structure and Inorganic Salts Effects

• Published in: Phosphorus, sulfur, and silicon and the related elements Vol. 183; no. 1; pp. 21 - 33
• Main Authors: Mečiarová, Mária, Toma, Štefan, Loupy, André, Horváth, Branislav
• Format: Journal Article
• Language: English
• Published: ABINGDON Taylor & Francis Group 01.01.2008; Taylor & Francis
• Subjects: Ar mechanism; Chemistry; Chemistry, Inorganic & Nuclear; Chemistry, Organic; halopyridines; inorganic salt effects; microwave irradiation; phosphine structure effects; Phosphonium salts; Physical Sciences; Science & Technology; phosphonium salts; MICROWAVE ACTIVATION; halopyridines; microwave irradiation; inorganic salt effects; phosphine structure effects; SNAr mechanism; HETEROCYCLIC-COMPOUNDS
• ISSN: 1042-6507; 1563-5325
• DOI: 10.1080/10426500701545950

Solvent-free reactions of 2- and 3-halopyridines with PPh 3 , PBu 3 , and PCy 3 were studied under conventional heating, as well as under microwave irradiation. No difference was observed in the reaction course between classical and microwave reactions. 2-Bromopyridine gave quantitative yields of 2-pyridyltriphenylphosphonium bromide within few minutes at 190°C. Equimolar amounts of some inorganic salts (LiPF 6 , LiOTf, LiBr, NaPF 6 , KPF 6 ) were necessary for the reactions of the other 2-halopyridines. 3-Halopyridines did not react with PPh 3 even in the presence of LiPF 6 . Their reactions with PCy 3 in the presence of LiPF 6 resulted in the quantitative formation of dicyclohexylphosphine oxide.