Abstract
In this paper, we explored the synthesis of benzimidazole by the reaction of DMF and o-phenylenediamine. In the process of catalyst screening, we found that 4-amino-3-hydroxybenzoic acid, benzoic acid, and benzene-1,3,5-tricarboxylic acid could catalyze the reaction. Moreover, the calcium 4-amino-3-hydroxybenzoate and CO2 could more effectively catalyze the reaction, the synergistic effect of CO2 and 4-amino-3-hydroxybenzoic acid calcium salt can increase the yield of benzimidazole from 28% to 94%.
Highlights
Benzimidazole and its derivatives are fundamental building blocks in many kinds of functional compounds, especially in drugs and bioactive molecules,[1,2,3,4] and widely used in anti-cancer,[5] anti-inflammatory,[6] anti-bacterial,[7] anti-oxidant,[8] anti-coagulant[9] and so on.[10]
Benzene-1,3,5-tricarboxylic acid, 4-amino-3-hydroxybenzoic acid, o-aminophenol, calcium benzoate, N,N-dimethylformamide and o-phenylenediamine were purchased from Shanghai Aladdin Biological Technology Co., Ltd. (Shanghai, China)
The benzimidazole could be obtained in 84% yield after 24 hours of reaction at 140 °C when the equivalent of 4-amino-3-hydroxybenzoic acid was 0.5 (Table 1, entry 5)
Summary
Benzimidazole and its derivatives are fundamental building blocks in many kinds of functional compounds, especially in drugs and bioactive molecules,[1,2,3,4] and widely used in anti-cancer,[5] anti-inflammatory,[6] anti-bacterial,[7] anti-oxidant,[8] anti-coagulant[9] and so on.[10]. Hydrochloric acid is usually used in the synthesis of benzimidazoles, but it is corrosive and impossible to be reused.[19] many catalysts had been prepared for this reaction, for instance, azole-anion-based aprotic ionic liquids with tetrabutylphosphonium hydroxide,[23] ionic liquids of hydrochloric acid,[24] glyoxylic acid,[10] B(C6F5)[316] and zinc acetate dehydrate.[11] But they are usually used in combination with reducing substances such as hydrosilane, hydrogen, boron phosphorus and transition metal salts. Their application is undesirable under the green chemistry principles.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
