曼尼希碱缓蚀剂的组成和缓蚀性能相关性的量子化学研究

QUANTUM CHEMICAL STUDY ON THE STRUCTURE-ACTIVITY RELATIONSHIP OF MANNICH BASE AS CORROSION INHIBITOR

以正己胺、苯甲胺和环己胺为原料,分别与苯乙酮和甲醛反应合成了3种单曼尼希碱缓蚀剂BK1,BK2,BK3(统称BK组缓蚀剂),分别与丙酮和甲醛反应合成了3种单曼尼希碱缓蚀剂PA1,PA2,PA3(统称PA组缓蚀剂);然后以BK2为前体,与丙酮和甲醛反应合成了双曼尼希碱缓蚀剂D1;以PA1为前体,与环己基甲酮和甲醛反应合成了双曼尼希碱缓蚀剂D2。研究了上述8种缓蚀剂在酸性介质中对N80试片的缓蚀作用,采用量子化学密度泛函理论探讨了合成的曼尼希碱缓蚀剂分子结构参数和缓蚀性能的关系。结果表明,计算得到的最低未占轨道能级(ELUMO)、前线轨道能隙(ΔE)、偶极矩(μ)、分子极化率(α)和范德华表面负静电势面积(AS-)与曼尼希碱缓蚀率的灰色关联度为0.736~0.891,线性决定系数R2为0.556~0.968。BK组缓蚀剂分子具有的苯甲酰基,使得BK组缓蚀剂的ELUMO、ΔE均低于具有乙酰基的PA组缓蚀剂,而其μ,α,AS-均高于PA组缓蚀剂。与BK1分子的正己基及BK3分子的环己基相比,BK2分子的苯甲基使其α和AS-增大;分子的α和AS-由大到小的顺序为BK2>BK1>BK3。BK组缓蚀剂中BK2的缓蚀率最佳,以此为前体合成得到的双曼尼希碱D1的缓蚀效果进一步增强,在相同条件下对N80试片的缓蚀率由99.2%提高到99.4%。

Three kinds of Mannich base corrosion inhibitors BK1,BK2 and BK3(collectively referred to as BK group corrosion inhibitors)were synthesized by reacting hexylamine,phenylmethylamine and cyclohexylamine with acetone and formaldehyde,respectively.Three kinds of Mannich base corrosion inhibitors(collectively referred to as PA group corrosion inhibitors)were synthesized by reacting hexylamine,phenylmethylamine and cyclohexylamine with acetone and formaldehyde,respectively.In addition,double-Mannich base corrosion inhibitor D1 was synthesized by reacting BK2 with acetone and formaldehyde as a precursor.Double-mannich base corrosion inhibitor D2 was synthesized by reacting PA1 with cyclohexylmethanone and formaldehyde as precursor.The corrosion inhibition of N80 specimens in acidic media was investigated with the eight corrosion inhibitors mentioned above.The quantum chemical parameters of the Mannich base molecules were calculated using density functional theory.The results of grey correlation analysis show that the energy of the lowest unoccupied molecular orbital(ELUMO),the energy gap(ΔE),dipole moment(μ),isotropic average polarizability(α)and negative electrostatic potential of van der Waals surface area(AS-)had the good correlation with the inhibition rate of Mannich base.The grey correlation degrees ranged from 0.736 to 0.891 and the linear determination coefficients ranged from 0.556 to 0.968.It was concluded that some quantum parameters,such as ELUMO andΔE of the BK series were lower than those of the PA series,while theirμ,αand AS-were higher than those of the PA series.Compared to the hexyl group of the BK1 and the cyclohexyl group of BK3,the phenylmethyl group of the BK2 increased the polarizability and the area of the negative electrostatic potential,resulting inαand AS-BK2>BK1>BK3.The ELUMO andΔE of D1 and D2,due to the secondβ-carbonyl group,were lower than those of BK2 and PA1.The best corrosion inhibition efficiency was obtained for BK2 in the BK series,and the corrosion inhibition increased with further synthesis to obtain double Mannich base D1.The corrosion inhibition effect was further increased from 99.2%to 99.4%for N80 specimens under the same conditions.