Workup for Removing Amines

Amines will partition into the organic layer during a typical aqueous workup. Three methods for rendering them water-soluble are listed below. Methods 2 and 3 should only be used when your product is acid stable.

1. Wash the organic layer several times with 10% copper sulfate (aqueous and blue). The copper-complexed amine will partition into the aqueous solution, which turns purple. Continue to wash with the copper sulfate solution until no color change is observed.
   Rule of Thumb (see all): When removing amine solvent, wash with 10X the volume of saturated aqueous copper sulfate solution.
2. Wash the organic layer several times with dilute HCl solution. The protonated amine will partition into the aqueous layer.
3. Acidify until reaction turns very cloudy (typically pH 4 or lower). The amine should be protonated at low pH and become insoluble in the organic layer, and can be removed via aqueous wash.