Pyridine based N-heterocyclic compounds as aqueous phase corrosion inhibitors: A review

Nitrogen based heterocyclic compounds are extensively used as corrosion inhibitors because of their ability to form strong coordination bonding with the metallic atoms. In the present review article anticorrosive effect of pyridine based compounds is surveyed. Generally, pyridine derivatives with electron withdrawing and electron donating substituents showed higher anticorrosion effect than that of the native pyridine. Pyridine derivatives containing polar substituents at 2nd and 6th positions form highly stable chelating complexes. The mono- (2nd position) and di- (2nd and 6th position) substituted pyridine derivatives preferably act as bidentate and tridentate ligands, respectively. Literature study showed that various reports are available on the anticorrosive behavior of pyridine based organic corrosion inhibitors. Generally, pyridine based N-heterocyclics act as mixed-type inhibitors and their adsorption obeyed the Langmuir adsorption isotherm. Computational based analyses show that pyridine based N-heterocyclics interact with metallic surface using donor-acceptor interaction and they acquire relatively flat orientation on the metallic surface. Different families of pyridine based N-heterocyclics are widely used as metallic corrosion inhibitors. Present review article describes the collection of major reports published on the anticorrosive effect of pyridine based N-heterocyclics.