green synthesis of benzimidazole derivatives: an overview on green chemistry and its applications

The chemical substances in our environment are rising day by day. only some of them are degraded, but most of them are non-degradable. these non-degradable substances produce pollutions which cause instability, harm or discomfort to the ecosystem as pollutions and create a risk to the environment. to reduce the possibility of a system we must reduce the risk not by altering the effect but by the cause. thus, green chemistry (gc) concept was introduced, and it is a rapidly emerging field of chemistry. the gc is the design of chemical products and procedures that decrease or remove the use and production of harmful substances. in recent years, various heterocyclic compounds have appeared owing to the extensive varieties of their pharmacological activities. benzimidazole is a heterocyclic aromatic compound. it is a vital and advantaged structure in medicinal chemistry and plays a role with ample therapeutic activities like analgesic, anti-inflammatory, antiulcer, antihypertensive, antibacterial, antiviral, antifungal, anticancer and antihistaminic. because of its value, the processes for their synthesis have become a focus of synthetic chemists. therefore, this review aims at compiling the chemistry of differently substituted benzimidazoles and some other methods. conventional methods of synthesis need longer heating time, complicated and tedious apparatus set up which result in high cost and pollution in contrast to greener methods which are inexpensive.