Synthesis And Corrosion Inhibition Of Derivative Of Benzyl Chloride Quaternary Ammonium Salt (Bqd)

Corrosion inhibitors are used extensively in acidizing engineering to inhibit the corrosion of metal lines and equipments caused by hydrochloric acid.Heterocyclic quaternary ammonium salts are effective corrosion inhibitors.N-Benzylquinolinium chloride?BQC?is effective corrosion inhibitor in acidizing engineering in some literatures,however the corrosion inhibition could not meet evidently the specifications?SY/T5405-1996?of industry standards.Otherwise,the compound,named derivative of benzyl chloride quaternary ammonium salt?BQD?separated from the synthesis of BQC,displayed excellent corrosion inhibition.So the synthesis of BQD would be investigated,so that the BQD would be produced as many as possible in the synthesis of BQC.According to the formation mechanism of BQD from BQC,it is proposed that alkali and oxygen should be introduced into the the formation of BQD.The results showed that the yield of BQD was effected by basicity and its quantity,temperature and reaction time,etc.The appropriate reaction condition to synthesize BQD was obtained.Firstly,the BQC could be produced under equal molar ratio of quinoline and benzyl chloride with water of the same quality as the substrate reacting for 4 hours at 80?.Secondly,the mixture of BQC was cooled to 35?,then Na₂CO₃ was added with a molar ratio of quinoline to Na₂CO₃ in 0.6:1 and oxygen were introduced to the mixture for 4 hours at 35?.The yield of the crude product obtained by the optimum synthesis route was 38.47%,in which the yield of BQD was 18.10%.The corrosion inhibition of crude products containing BQD to N80 steel was evaluated by static gravimetric measurement in 15%hydrochloric acid at 90?.The results showed that corrosion rate was 2.75 g·m^-2·h^-1 at the concentration of 0.3%,which reached the first level in the specifications of SY/T5405-1996.The crude product of BQD was purified by column chromatography to get the yellow component,which was identified by elemental analysis,NMR and high performance liquid chromatography/high resolution mass spectromettry?HPLC-HRMS?,etc.The corrosion inhibition mechanism of BQC and BQD was studied by static gravimetric measurement,electrochemical experiment,isothermal adsorption model and scanning electron microscopy,and the reason why BQD presented more effective corrosion inhibition than BQC was described.