Dicyclohexylcarbodiimide → N,N'-Dicyclohexylurea

Participants

Reaction Steps

To a solution consisting of 0.7 g (1.3 mmol) N,N'-(2-aminoethyl) trans-1,2-diaminocyclohexane-N,N',N",N'",N'"hexaacetic acid in 50 ml dimethylsulfoxide was added 0.9 g (7.8 mmol) N-hydroxysuccinimide and 0.8 g (3.9 mmol) dicyclohexylcarbodiimide. This was stirred at room temperature for 48 hr., during which the white fluffy solid of dicyclohexyl urea formed. This solid was removed by filtration and the filtrate was concentrated to a thick oil under reduced pressure. A solid precipitated from the oil upon the addition of acetonitrile. This solid was collected, washed with cold acetonitrile and dried under vacuum to give 0.54 g of a light brown solid. NMR showed an average of 2 NHS esters so the yield is 56%. No further purification of the solid was attempted; mp 125°-140° C.

Provenance & Evidence