Green corrosion inhibitors derived through one-step multicomponent reactions: recent developments

One of the most effective methods of corrosion mitigation is the implementation of synthetic corrosion inhibitors. Several inorganic and organic compounds have been used as effective corrosion inhibitors for metals and alloys in different electrolytes. The use of inorganic compounds as inhibitors is limited because of their toxic nature and bioaccumulation ability. Nevertheless, organic compounds are the most effective and economical alternatives to be used as corrosion inhibitors. Because of their high effectivity, ease of synthesis, ease of application, possibility of recyclization, and cost-effectivity, organic compounds are most extensively used as corrosion inhibitors. Most of the effective corrosion inhibitors are the heterocyclic compounds containing polar functional groups and multiple bonds in their molecular structures. They inhibit corrosion by adsorbing on the metallic surface and their adsorption obeys the physisorption, chemisorption, or mixed (physiochemisorption) modes of adsorption. After getting adsorbed on the metallic surface, organic compounds form a surface protective film at the interface of metal and electrolyte and protect from corrosion. Mostly, organic compounds are derived using a traditional multiple step reaction which is considered to be highly expensive and nonenvironment-friendly as it discharges a huge amount of solvents and chemicals into the surrounding environment. The increasing ecological awareness and strict environmental regulations do not permit the synthesis of corrosion inhibitors using traditional methods. In view of this, one-step multicomponent reactions (MCRs) have emerged as a green and environment-friendly approach, and these are associated with several advantages including high synthetic yield, ease to perform, and the lower number of purification and workup steps. Recently, several compounds derived through MCRs have been used as corrosion inhibitors for metals and alloys. This chapter describes some of the work described in the literature. The chapter also describes the advantages of the MCRs over traditional syntheses.