Green Microwave‐Assisted Synthesis of Cyclic/Acyclic Ureas from Propylene Carbonate

Abstract

Herein, an organocatalyzed synthetic pathway for the preparation of (a)cyclic ureas from their parent primary aliphatic or aromatic mono‐/diamines with propylene carbonate (PC) as a carbonylating agent (CAT) obtaining reasonable to very good yields with high selectivity. Our method is considered green as nine out of twelve green chemistry principles (GCPs) are fulfilled. Most importantly, the absence of solvent, energy‐efficient pathway, in addition to the ease of synthesis and separation, under fast reaction times down to a few minutes together with the straightforward workup with minimum use of organic solvents. Our method was successful in preparing 1,3‐diphenylurea from aniline giving 8 % yield in 10 minutes, to our knowledge, this was not previously reported using aromatic amines with carbonate esters. The prepared compounds were fully characterized by spectroscopic and thermal techniques. The method is applicable for primary rather than secondary amines, which implies high chemoselectivity of the former for the synthesis of urea compounds.

New insights into urethane alcoholysis enable chemical full recycling of blended fabric waste

“…Thus, as the reaction progress, the remaining carbonyl (CO) of the urethane group is first transformed into ethylene carbonate (products 6). Subsequently, the carbonylation 63,64 reaction of ethylenediamine with ethylene carbonate generates 2-imidazolidinone (products 7), which also promotes the amide-esterification reaction during urethane alcoholysis by consuming ethylene carbonate. During methanol transesterification, product-1 and product-2 are transformed to product-8 and product-9, respectively.…”

CS2/CO2Utilization Using Mukaiyama Reagent as a (Thio)carbonylating Promoter: A Proof-of-Concept Study

“…The problems associated with the common (thio)­carbonylating agents such as phosgenes and isocyanates as well as conventional processes make it necessary to search for benign alternatives and safer methods to avoid potential catastrophes such as in Bhopal, India, 1984 and to eliminate toxic/hazardous byproducts . Thus, green approaches are directed toward microwave-assisted, solvent-free methods by employing green carbonylating agents. − Interestingly, Dondoni group reacted CS 2 with monofunctionalized amine in the presence of triethylamine (Et 3 N) and 2-chloro-1-methylpyridinium iodide, [Mukaiyama reagent (CMPI), Scheme ] to prepare isothiocyanate …”

Unconventional CO2-Binding and Catalytic Activity of Urea-Derived Histidines

“…From a carbon capture and utilization (CCU) point of view, one important CO 2 utilization products are cyclic carbonates (CCs) as catalyzed by different onium salts such as imidazolium, , quaternary ammonium, , quaternary phosphonium, , pyridinium salts, , and others . Another essential functional group that is not fully explored for the synthesis of CCs, and its role in catalysis is urea motif due to its thermal and acid resistivity, cost-effectiveness, abundance, hydrogen bond donor (HBD) character, and as an augmentation to our efforts on exploiting/developing synthetic methodologies of ureas as polymers, fine chemicals, or CO 2 capturing agents. ,,− Liu et al synthesized urea-derived ILs, demonstrating their ability to capture CO 2 and to convert epoxides to CCs in good-to-excellent yields under HBD-organocatalyzed conditions. Interestingly, urea-functionalized poly-imidazolium-ILs, heterogeneous urea-derived framework catalysts supported on silica, and several systems were reported in the literature to produce CCs. − The chemical structures of several urea-based compounds reported in the literature for CO 2 capture and utilization are presented in Scheme A,B, respectively.…”