EDC (Water-Soluble Carbodiimide)

EDC is a carbodiimide coupling reagent useful in solution phase coupling and protein modification. This coupling reagent and the urea by-product of coupling are both water soluble, thus allowing the removal of excess reagent and urea byproduct by simple extraction. 

Coupling with EDC 

1. Dissolve the N-protected amino acid and the amino acid ester to be coupled in dichloromethane(DCM). 

2. Cool the mixture in an ice bath. 

3. Add 1.2 equivalents of EDC and stir the mixture.

 4. When the reaction is complete, wash the mixture with water to remove excess EDC and urea by-product. 

5. Dry the organic phase over sodium sulfate, filter, and evaporate to obtain the crude product.