Zinc Chloride, typ. 25 % solution in 2-Methyl-THF
The use of a 'ready-made' 2-Methyl-THF solution avoids the handling of the very hygroscopic and dusty ZnCl2 powder.
The ZnCl2 / 2-Methy-THF solution was developed mainly for the application in organic synthesis, e.g.:
-transmetallation of organomagnesium and organolithium compounds to the corresponding zinc reagents for C-C coupling reactions (Negishi protocol).
-formation of zinc enolates by deprotonation of carbonyl compounds using standard bases followed by transmetallation with ZnCl2.
-catalysis of cycloaddition reactions e.g. Diels-Alder reactions of electron rich dienes with carbonyl compounds.
-preparation of selective reducing agents, e.g. Zn(BH4)2 by reaction of NaBH4 with ZnCl2.
McGarvey, G.J. in Encyclopedia of Reagents for Organic Synthesis, Paquette, L.A., Ed. John Wiley and Sons, New York (1995), Vol. 8, 5544.