Scientific advances in sulfuric acid free toluene nitration

The nitration of toluene is an ubiquitous reaction whose mono nitro products find applications in pharmaceuticals, perfumes, explosives and plastics. The conventional process of treating toluene with mixed acids leads to an undesirable product distribution besides being energy intensive and environmentally unfriendly. Hence the worldwide research on alternative greener technologies has intensified. This paper provides a comprehensive review on the sulfuric acid free nitration of toluene covering alternative options on nitrating agents, catalysts, their properties, compatible solvents, reaction media, process kinetics, mechanisms and reaction engineering studies. New opportunity areas for future research are identified.