5-Chloroindole can be synthesized by using 3-chlorobenzaldehyde as starting reagent. 5-Chloroindole is a 5-substituted indole. It undergoes electropolymerization to form a redox-active film consisting of a cyclic trimer and chains of linked cyclic trimer (polymer).It is a potential positive allosteric modulator (PAM) of the 5-HT3 receptor.It has been reported as strong inhibitor of the copper dissolution in acidic sodium chloride solution.It has been tested as corrosion inhibitor of mild steel in 1N deaerated sulphuric acid. Synthesis of 5-chloroindole, via nitration of indoline has been described. 5-Chloroindole can be synthesized by using 3-chlorobenzaldehyde as starting reagent. 5-Chloroindole is a 5-substituted indole. It undergoes electropolymerization to form a redox-active film consisting of a cyclic trimer and chains of linked cyclic trimer (polymer).It is a potential positive allosteric modulator (PAM) of the 5-HT3 receptor.It has been reported as strong inhibitor of the copper dissolution in acidic sodium chloride solution.It has been tested as corrosion inhibitor of mild steel in 1N deaerated sulphuric acid. Synthesis of 5-chloroindole, via nitration of indoline has been described.