Darzens halogenation

The Darzens halogenation , named after the French chemist AG Darzens is a name reaction from the organic chemistry and was first published in the 1911th The reaction describes the synthesis of halogenated hydrocarbons from alcohols .

Overview reaction

In an S _N i reaction , an alcohol reacts with thionyl halide using tertiary amines or pyridine to form a halogenated hydrocarbon:

Reaction mechanism

The mechanism is described in the literature and is illustrated with thionyl chloride :

The alcohol 1 reacts with thionyl chloride 2 with the addition of pyridine to form intermediate 3 . The pyridine is protonated and released together with a chloride ion. Subsequent electron and atom rearrangement in 3 produces the chlorinated hydrocarbon ( 4 ) after sulfur dioxide has been split off .

application

In a Darzens halogenation, cholesterol reacts with the addition of thionyl chloride and pyridine to form cholesterol chloride.

Individual evidence

↑ G. Darzens: Nouvelle method d'etherification des alcools par les hydracides In: Comptes rendus de l'Académie des sciences . 152, 1911, p. 1314.
↑ Reinhard Brückner: reaction mechanisms , Speltrum Akademischer Verlag, 2004, p. 93, ISBN 978-3-8274-1579-0 .
^ Z. Wang: Comprehensive organic name reactions and reagents Volume 1 . John Wiley, Hoboken (NJ) 2009, ISBN 978-0-470-28662-3 , pp. 846-847 .
↑ Paul J. Daughenbaugh and James B. Allison: THE ACTION OF THIONYL CHLORIDE UPON CHOLESTEROL AND CERTAIN OTHER ALCOHOLS In: J. Am. Chem. Soc. 51 (12), 1929, pp. 3665-3667, doi: 10.1021 / ja01387a031 .

[1] G. Darzens: Nouvelle method d'etherification des alcools par les hydracides In: Comptes rendus de l'Académie des sciences . 152, 1911, p. 1314.

[2] Reinhard Brückner: reaction mechanisms , Speltrum Akademischer Verlag, 2004, p. 93, ISBN 978-3-8274-1579-0 .

[:Wang-3] Z. Wang: Comprehensive organic name reactions and reagents Volume 1 . John Wiley, Hoboken (NJ) 2009, ISBN 978-0-470-28662-3 , pp. 846-847 .

[4] Paul J. Daughenbaugh and James B. Allison: THE ACTION OF THIONYL CHLORIDE UPON CHOLESTEROL AND CERTAIN OTHER ALCOHOLS In: J. Am. Chem. Soc. 51 (12), 1929, pp. 3665-3667, doi: 10.1021 / ja01387a031 .