The inhibition effects of dimethylol-5-methyl hydantoin and its derivatives on carbon steel alloy

Dimethylol-5-methyl hydantoin mhd and its derivatives were used as corrosion inhibitors to protect carbon steel alloy against deterioration from corrosion. effectiveness of heterocyclic molecules as corrosion inhibitor is based on their chelating, temperature and ph range. generally, the action and the formation of an insoluble physical diffusion barrier on the electrode surface prevent the metal reaction and dissolution. dimethylol-5-methyl hydantoin and its derivatives containing hetero atom, such as n, with free electron pairs which are readily available for sharing, are found to be effective corrosion inhibitors for many metals and alloys. it has been commonly recognized that feed back coordinate covalent bonds formed between organic inhibitors and metal surface during chemical adsorption process. mhd as heterocyclic compound containing n-atoms was used to synthesis four compounds by its reaction with the prior starting materials to produce the compounds (a, b, c, and d). the study exhibited that mhd has higher efficiency(97.81%) than other inhibitors (a-d)inhibitors due the steric effect in case of (a-d) inhibitors, but the efficiency of mhd inhibitor was decreased as temperature increased due to destroying of the protective film of this inhibitor at 40ºc , also the efficiency decreased for all inhibitors mhd and (a-d) in acidic media due to due to protonation of some hetero atoms that presence in meaning inhibitor that lower the basicity for other non protonated hetero atoms then reduce the efficiency. this true in basic media because in basic media caustic corrosion is an important factor that reduced the efficiency due to solubility of some of protective film. different behaviors for inhibitors as temperature change, some of them has physical adsorption mode c and d inhibitors and other has chemical adsorption mode mhd,a and b due to their variation behaviors with temperature.