The Study On Functionalized Ionic Liquid Of Its Design,Synthesis And Corrosion Inhibited

In recent years,in the fields of organic synthesis and corrosion inhibition,ionic liquids have received comprehensive attention on account of their simple synthetic methods,large potential quantities,good stability,strong designability,and green environmental protection.With the deepening of the research on functionalized ionic liquids,specific ionic liquids can be synthesized or specific groups can be attached to the ionic liquids,which make ionic liquids have broad application in organic synthesis and corrosion inhibition.Therefore,we designed and synthesized two ionic liquids with different structures and investigated their catalytic properties corrosion,inhibition properties.The research contents and conclusions were described below:（1）Six imidazole ionic liquids were synthesized by a two-step method,and the catalytic effect of the Friedlander reaction in the absence of other solvents and catalysts was investigated.The reaction temperature,reaction time,amount of ionic liquids,and molar ratio of reactants effect on product yield were investigated.The experimental results show that the ionic liquid[Bmmim][Im]has the best catalytic effect.The reaction temperature is 80 ^oC,the reaction time is24 h,the amount of ionic liquid is 5 m L,and 2-amino-3-pyridinecarbaldehyde reacts with diphenylethanone.When the molar ratio of raw materials is 0.6:1,the product yield is the highest,and the ionic liquid can be reused 4 times without obvious activity loss.Under the optimal reaction conditions,the compatibility of ionic liquid-catalyzed Friedlander reaction system was studied by using 2-amino-3-pyridinecarbaldehyde and ketones（aldehydes）as raw materials.Finally,using 2,3-diphenyl-1,8-naphthyridine and carboxyethyl thiosuccinic acid（CETSA）as raw materials,[1,8-Nap][CETSA]was generated as a corrosion inhibitor to explore1,8-naphthyridine corrosion inhibition performance.With Q235 steel in 1.0 M HCl solution,the corrosion inhibition performance of[1,8-Nap][CETSA]was investigated by static weight loss experiments,electrochemical measurement and surface analysis technology.The results show that the corrosion inhibitor molecule[1,8-Nap][CETSA]is adsorbed on the metal surface to form a dense protective film,preventing the contact between the metal and the acid solution.Meanwhile,[1,8-Nap][CETSA]is a mixed corrosion inhibitor that mainly inhibits the cathodic reaction.（2）Hexamethylenetetramine（HMT）and CETSA were used as raw materials,the molar ratio of raw materials was changed,different kinds of ionic liquids were synthesized by one-step method,and their structures were confirmed by the characterization method of ¹H NMR.The ionic liquid synthesized which described above was used as a corrosion inhibitor.Its corrosion inhibition performance on Q235 steel was investigated in 10%HCl solution.The results of static weight loss experiment and electrochemical test show that when H₂C₁ is used as corrosion inhibitor and the addition amount is 0.7%,the corrosion inhibition rate of Q235 steel is higher than H₁C₄,H₁C₃,H₁C₂,H₁C₁ and H₃C₁.Through further study,it was found that with 0.7%H₂C₁corrosion inhibitor was added to different concentrations of HCl solution（5%,10%,15%,20%,25%）,the corrosion inhibition rate was less affected by the acid concentration.The X-ray photoelectron spectroscopy（XPS）verified that the H₂C₁ molecule had been adsorbed on the surface of the steel sheet and formed a layer of adsorption film,which reduced the corrosion of the metal.Next,the corrosion inhibition performance of H₂C₁,[Bmim][Br]and[C₄Py][Br]was compared in 10%HCl solution,and the repeated use performance of the corrosion inhibitor solution was explored.The corrosion inhibition application rate has always been above 90%,the corrosion rate of[Bmim][Br]and[C₄Py][Br]inhibitor in high concentration HCl is less than50%,and after 5 times of use,the inhibition rate decreases obviously.The scanning electron microscope（SEM）was used to verify the results of the cyclic use experiment.After Q235 steel was soaked with a corrosion inhibitor containing H₂C₁,the surface of the steel sheet was smooth and flat,which indicated that the steel sheet was effectively protected by H₂C₁.However,after the Q235 steel was soaked with two corrosion inhibitors,[Bmim][Br]and[C₄Py][Br],the surface of the steel sheet was uneven,indicating that the corrosion inhibition effect of H₂C₁ was significantly better than the other two corrosion inhibitors.