Alternatives to Phosgene and Carbon Monoxide: Synthesis of Symmetric Urea Derivatives with Carbon Dioxide in Ionic Liquids

Abstract

Simpel, sauber, sicher: Disubstituierte Harnstoffderivate lassen sich effizient aus Aminen und CO2 synthetisieren mit einem Katalysatorsystem aus CsOH in einer ionischen Flüssigkeit (IL). Die Produkte sind leicht abtrennbar, und das Katalysatorsystem kann ohne Desaktivierung wiederverwendet werden (siehe Bild).

Toward green catalytic synthesis—Transition metal-catalyzed reactions in non-conventional media

“…Carbonylation of olefins and aryl halides with nucleophiles in ILs to give the corresponding esters or amides has also been reported, with palladium being used as catalyst in most cases [191][192][193][194][195][196]; examples include the Pd-catalyzed hydroethoxycarbonylation of styrene [194], and Rh-catalyzed hydroaminomethylation of long-chain olefins with secondary amines [195]. A Pd-catalyzed hydroxycarbonylation of vinyl bromides (E/Z ≥ 5:1) led to the corresponding ␣,␤-unsaturated carboxylic acids in moderate to very good yield (up to 99%) with excellent stereoselectivity (E/Z up to 99:1) in [bmim]PF 6 , as shown in Scheme 23 [196].…”

Important Green Chemistry and Catalysis: Non‐phosgene Syntheses of Isocyanates – Thermal Cracking Way

“…were also investigated, [10][11][12][13] however, these active components are expensive, easy to lose, difficult to reuse. Furthermore, the oxidative carbonylation of amines needs to conduct at high temperature and pressure, and the mixture of CO and O 2 often involves the rigorous safety issues.…”

Unprecedented Catalytic Hydrogenation of Urea Derivatives to Amines and Methanol

“…[4] In addition, sugar-urea-salt melts were used as "green solvents" for Rh-catalyzed hydrogenation reactions and found to be sustainable reaction media. [5] Notably, alkyl and aryl urea compounds are readily synthesized from reactions of amines with CO 2 in the presence of various catalysts, such as 1,8-diazabicyclo-[5.4.0]undec-7-ene, [6] CsOH, [7] Cs 2 CO 3 , [8] Au/polymers, [9] [Bmim]OH [10] or KOH/PEG1000, [11] and by using ionic liquids, N-methylpyrrolidone, and supercritical carbon dioxide as solvents. Transition-metal-catalyzed synthesis of urea derivatives was also reported.…”