Compositions may include a corrosion inhibitor including a heterocyclic diamine prepared from the reaction of an alkyl diamine and an aldehyde, wherein the alkyl diamine has the general formula: R4NH(CH2)nNHR5, where n is an integer between 3 and 6, and R4 and R5 are independently hydrogen or a C2-C30 saturated or unsaturated hydrocarbon radical. Methods may include contacting a metal surface with a corrosion inhibitor composition, wherein the corrosion inhibitor includes a heterocyclic diamine corrosion inhibitor from the reaction of an alkyl diamine and an aldehyde, wherein the alkyl diamine has the general formula: R4NH(CH2)nNHR5, where n is an integer between 3 and 6, and R4 and R5 are independently hydrogen or a C2-C30 saturated or unsaturated hydrocarbon radical.