Imidazoline adherents to heterocyclic group of compounds which has five membered rings with two nitrogen atoms.

Classified into two groups, Cationic & Amphoteric Imidazolines, the former is the Ammonium Mono Quaternary Salts with asymmetrical structure determined by cations, optically functioning in the aqueous solution where ionized.

The most widely used representative of this group is the tallow alkyl derivative. The unsaturated C₁₈ consists of one double bond in a CIS isomer configuration which helps in lowering its melting point and is the sole reason behind its liquid state at room temperature. The saturated C₁₈ has no double bonds, providing rigidity to the molecule and raising the melting point with reduced flow ability.

The nitrogen atom in the structure tends to provide some particular attributes like enhanced functional derivation, allowing the study of various functional group of Imidazoline radicals without effecting its paramagnetic properties. The head and the pendant group of the molecule helps in bonding of the same to surface while the hydrocarbon tail forms a protective layer or adsorptive layer.

Inhibition Mechanism:

The long hydrocarbon chain forms hydrophobic layers in solution that blocks any kind of reaction between the corrosive agent and the metal ions. The pendant side with an active functional group has nitrogen, oxygen and other heteroatoms, is responsible for chemical adsorption over the surface. The other Imidazoline derivatives act as cationic surfactants, determined by the nature of hydrocarbon or substituent groups attached to carbon or nitrogen atom of the heterocyclic ring.