Abstract A base-free catalyst system Co (acac) 3/BMMImCl was developed for the carbonylation of amines with CO 2. 45%\ 2-81% isolated yields for N, N-dialkylureas and 6%\ 2-23% isolated yields for N, N-diarylureas were obtained. The catalyst system was recovered and reused without significant loss in activity. In this catalyst system, the base catalyst and chemical dehydrant were efficiently avoided. Different reaction conditions ...