After the dehydration using DCC (N,N'-dicyclohexylcarbodiimide) in DCM, I have a single product after confirming from 2D TLC. How could i remove the DCC from the product. Aqueous workup I think will not work as DCC is insoluble in water and soluble in organic solvents. Apart from column chromatography, is there is any way to remove DCC from the mixture.
I would suggest trituration of your product, especially if it is a reasonably polar material with either a 1:1 mixture of ethanol and hexane or with diethyl ether, will remove the DCCU.
you are using DCM as solvent, most of DCU will be precipitated, then can be isolated from reaction mixture. DCU residue could be washed by 5% kHSO4, 5% NaHCO3 in sequence.
if additional crystallization performed , such as ethanol/ toluene, my experience, could be removed thoroughly
You could try methods mentioned above by other researchers.
Personally, even after chromatographic separation, one cannot guarantee its removal. I have seen traces of DCCU even after chromatographic separation.
These days I prefer DIC or HBTU over DCC.
Good Luck
Anwar A Hussain
I have checked the solubility and the compound is soluble is DCM, Ethyl acetate, diethyl ether, chloroform, methanol and ethanol.
I have found that DCCU is insoluble in acetonitrile while my organic products are typically soluble in MeCN so I can dissolve my desired product in MeCN, filter off the DCCU, and concentrate en vacuo.
Hi. Please note that DCU is not soluble in water. As your compound is soluble in Diethyl ether, DCU is practically insoluble in it. So make a slurry in diethyl ether and filter it. your compound will be in DEE and most of the DCU will be removed as solid.
Dicyclohexylcarbodiimide (DCC) is a popular coupling reagent used to form
amides and esters. The dicyclohexylurea byproduct of coupling is almost
insoluble in most solvents and is easily removed by filtration. In forming esters
and thioesters from acids and alcohols, addition of a catalytic amount of 4-(N,N-
dimethylamino)pyridine (DMAP) (Cat. No. RC8011) greatly enhances the rate of
reaction. When DCC is used in peptide coupling, 1-hydroxybenzotriazole (Cat.
No. RC8201) is added to suppress racemization. DCC coupling is also used to
prepare activated esters, such as p-nitrophenyl esters and pentafluorophenyl
esters, for peptide synthesis.
DCC has been used to prepare carboxylic acid anhydrides1
, ketenes2
, and
nitriles from primary amides3
by dehydration. It is also used in combination with
dimethylsulfoxide (DMSO) in the Pfitzner-Moffatt oxidation of alcohols to
carbonyl compounds under mild conditions.4
DCC is a sensitizer and can cause chemical burns. Wear safety goggles,
chemical resistant gloves, and protective garments when using DCC.
Coupling Using DCC
1. Dissolve one equivalent of the carboxylic acid and 1 equivalent of the
nucleophile (amine, alcohol, etc.) in dichloromethane (DCM). If the
nucleophile is an alcohol, add 0.1 equivalent of DMAP. Cool this mixture
in an ice bath.
2. Dissolve 1.1 equivalents of DCC in a minimum amount of DCM. Add this
solution with stirring to cooled mixture in the previous step. Equip the
flask with a drying tube and stir the mixture until the reaction is complete.
I quite agreed with Roshan Bodhe. You may take advantage of relative differences in solubility of DCC and your expected product in solvents and filter. Barret Kalindjian suggestions of (repeated) trituration may further remove DCC. However, if these fails you may try other alternative reagents e g. EDC.HCl, HBTU though more costly.
Filter the mixture, keep the filtrate in side fridge the DCC will precipitate more then you filter it again and again. But preferably EDC.HCl which is water soluble should be used that can be ride off through aqueous workup.
Hello,
Using acetonitrile is very efficient to filter off the DCU by product
You can even carry out your reaction in acetonitrile and filter at the end
Be well
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