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CO2 is a major greenhouse gas, and it is also a cheap and abundant C1 resource. Therefore, it is of great significance to convert CO2 into high value-added chemicals. Due to the high thermodynamic stability and chemical inertness of CO2, how to achieve chemical transformation under mild conditions (especially normal temperature and pressure) is a very challenging scientific problem.
Under the strong support of the National Natural Science Foundation of China and the Chinese Academy of Sciences, scientists from the Colloid, Interface, and Chemical Thermodynamics Key Laboratory of the Institute of Chemistry, Chinese Academy of Sciences conducted systematic research on CO2 chemical transformation and made important progress.
Through the construction of different catalytic systems, the researchers developed a green new route for the synthesis of benzimidazoles based on the three-component reaction of o-phenylenediamine or o-nitroaniline, CO2, and H2. The "one pot method" produced benzimidazole (Green Chem). ., 2013, 15, 95-99, Green Chem., 2014, 16, 3039-3044 ).
Oxidation of o-phenylenediamines with CO2 using ionic liquids [HDBU][OAc] as a solvent and catalyst resulted in the direct carbonylation reaction to produce benzimidazolone (ACS Catal., 2013, 3, 2076-2082).
Synergistic catalysis of commercial Pd/C and organic base DBU (1,8-diazacyclo[5,4,0]undecene-7,DBU) has been developed based on iodobenzene, CO2 and polymethylhydrogensilicon A new method for the direct synthesis of benzaldehyde from the reaction of oxymethylene (PMHS) (Chem. Commun., 2014, 50, 2330-2333).
Recently, the researchers developed the synthesis of bifunctional ionic liquids ([HDBU+][TFE-]) to develop the synthesis of quinazoline-2,4(1H,3H) from the reaction of CO2 with o-aminobenzonitriles at ambient temperature and pressure. A new catalytic system of diketones.
The ionic liquid is prepared by neutralization of an organic base and a weak proton donor trifluoroethanol (TFE) and can absorb CO2 at normal temperature and pressure with a trapping capacity of up to 1.01 mol/mol. It was found that the anions of ionic liquids can activate CO2 molecules, and the cations and anions of the ionic liquids activate the o-aminobenzonitrile substrate molecules through hydrogen bonding and eventually lead to the formation of products.
A series of reactions of o-aminobenzonitrile containing different substituents with CO2 were investigated and the corresponding quinazoline-2,4(1H,3H)-dione products were obtained. The ionic liquid enables the reaction to proceed without solvent and without metal participation, and is a green catalytic system that realizes chemical conversion of CO2 under mild conditions, and has broad application prospects (Angew. Chem. Int. Ed. 2014, 53, 5922). ~ 5925).
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