Issue 27/2014 - Benzimidazole adds a new green synthesis process

Benzimidazole adds a new green synthesis process

Recently, researchers from the Institute of Chemistry of the Chinese Academy of Sciences have made important progress in the chemical conversion of CO2, and developed a new synthesis process
of benzimidazole, benzimidazolone and benzaldehyde.

Since CO2 is thermodynamically stable and chemically inert, achieving chemical conversion under mild conditions, especially at ambient temperature, is an extremely challenging scientific problem
。 By constructing different catalytic systems, researchers developed a new green way to synthesize benzimidazole based on the reaction of o-phenylenediamine or o-nitroaniline, CO2 and H2, and prepared benzimidazole by "one-pot method"; Using ionic liquid [HDBU][OAc] as solvent and catalyst, o-phenylenediamine and CO2 direct carbonylation reaction to generate benzimidazolidone; A new method
for the direct synthesis of benzaldehyde based on the reaction of iodobenzene, CO2 and polymethylhydrosiloxane (PMHS) was developed by synergistic catalysis of commercial Pd/C and organic base DBU (1,8-diazacyclo[5,4,0]undecen-7).

In addition, researchers developed a novel catalytic system
for the synthesis of quinazoline-2,4(1H,3H)-dione compounds by reacting CO2 with anthranitriles at room temperature and pressure by designing and synthesizing bifunctional ionic liquids.
The ionic liquid is prepared by the neutralization reaction of organic bases and weak proton donor trifluoroethanol (TFE), which can absorb CO2 at atmospheric pressure and has a capture capacity of up to 1.
01mol/mol
.
It was found that the anion of ionic liquid can activate CO2 molecules, and its cations and anions jointly activate anthranitrile substrate molecules through hydrogen bonding to promote product formation
.
The researchers investigated the reaction of a series of anthranitriles containing different substituents with CO2 to obtain the corresponding quinazoline-2,4 (1H,3H)-dione products
.
The ionic liquid makes the reaction carried out under solvent-free and metal-free conditions, which is a green catalytic system to achieve the chemical conversion of CO2 under mild conditions, and has broad application prospects
.
(Hu Zhihong)