Dehydration of an Insoluble Urea Byproduct Enables the Condensation of DCC and Malonic Acid in Flow was written by O’Brien, Alexander G.;Ricci, Eric M.;Journet, Michel. And the article was included in Organic Process Research & Development in 2018.COA of Formula: C13H24N2O This article mentions the following:
A procedure for the preparation of N,N’-dicyclohexylbarbituric acid from DCC and malonic acid is described. Addition of phosphorus oxychloride to the reaction mixture facilitates dehydration of the insoluble byproduct N,N’-dicyclohexyl urea, enabling operation in continuous flow. A development approach based on in situ monitoring of batch reactions was used, which supported screening and determination of reaction conditions at small scale prior to scaleup in flow. Addnl. mechanistic understanding and control of impurity formation are presented. In the experiment, the researchers used many compounds, for example, 1,3-Dicyclohexylurea (cas: 2387-23-7COA of Formula: C13H24N2O).
1,3-Dicyclohexylurea (cas: 2387-23-7) belongs to amides. Because of the greater electronegativity of oxygen, the carbonyl (C=O) is a stronger dipole than the N–C dipole. The presence of a C=O dipole and, to a lesser extent a N–C dipole, allows amides to act as H-bond acceptors. Amides are not in general accessible by the direct condensation of amines with carboxylic acids for two reasons: first, both components are readily deactivated by a transfer of a proton from the acid to the amine and second, the hydroxy unit on the carbonyl of the acid is a relatively poor leaving group. Nevertheless, the formation of five- and six-membered rings is often surprisingly simple provided that other factors can be brought into play to assist in the condensation.COA of Formula: C13H24N2O
Referemce:
Amide – Wikipedia,
Amide – an overview | ScienceDirect Topics