Metal-free dehydrogenation of tri- and diethylamine with (C2F5)3PF2

• Published in: Journal of fluorine chemistry Vol. 207; pp. 12 - 17
• Main Authors: Bader, Julia, Neumann, Beate, Stammler, Hans-Georg, Ignat’ev, Nikolai, Hoge, Berthold
• Format: Journal Article
• Language: English
• Published: LAUSANNE Elsevier B.V 01.03.2018; Elsevier
• Subjects: Amines; Chemistry; Chemistry, Inorganic & Nuclear; Chemistry, Organic; Fluorine; Hydride abstraction; Pentafluoroethyl; Phosphate; Physical Sciences; Science & Technology; Pentafluoroethyl; Amines; Fluorine; Hydride abstraction; Phosphate; B(C6F5); ENAMINES; H-2
• ISSN: 0022-1139; 1873-3328
• DOI: 10.1016/j.jfluchem.2017.12.015

[Display omitted] •The reaction of the strong Lewis acid (C2F5)3PF2 with triethylamine is dominated by a hydride abstraction.•Thereby the hydridophosphate anion [P(C2F5)3F2H]- and the iminium ion [CH3CH = NEt2]+ are formed.•The iminium ion was subject to deprotonation by excess NEt3 which formally corresponds to the abstraction of dihydrogen. The reaction of the strong Lewis acid (C2F5)3PF2 with triethylamine leads to an initial hydride abstraction, resulting in the formation of the hydridophosphate anion [P(C2F5)3F2H]− and the iminium ion [CH3CH = NEt2]+. The latter is deprotonated by a second molecule NEt3 which corresponds to a formal hydrogen abstraction from the amine. The resulting nucleophilic enamine is trapped by a second equivalent of (C2F5)3PF2, ultimately yielding the β-aminovinylphosphorane derivative (C2F5)2PF2C2H2NEt2. The β-aminovinylphosphorane reacts with CsF to the corresponding trifluorophosphate derivative, [P(C2F5)2F3C2H2NEt2]−, which hydrolyzes to the aldehyde [P(C2F5)2F3CH2CHO]−, while the reaction with anhydrous HF yields the zwitterionic species [P(C2F5)2F3C2H3NEt2].