羧酸膦酸型化合物的阻垢缓蚀性能的量子化学研究

Quantum chemistry studies on microscopic mechanism of scale and corrosion inhibition for carboxyl phosphonic acid

运用密度泛函(DFT)理论,在B3LYP／6—31G*水平下,系统研究了2-膦酸基丁烷-1,2,4-三羧酸(PBTCA)、1,2,2-三膦酸基丁烷-4-羧酸(TPBCA)、3,3-二膦酸基戊烷-1,5-二羧酸(DPPDCA)这3种羧酸膦酸型阻垢缓蚀剂的分子结构与阻垢缓蚀性能之间的构效关系。结果表明,3种膦酸分子中的羧基和膦酸基中氧原子的负电荷较多,氧原子与垢晶体中的钙离子产生静电,这些氧原子对间距与方解石晶体生长面上的钙离子对间距匹配,产生晶格畸变,阻止垢体生长。计算得到3种分子的缓蚀能力为PBTCA>DPPDCA>TPBCA,并且得到羧基中的O原子、膦酸基中的O原子对缓蚀能力贡献较大。

The structure and activity relationships （SAR） of three carboxyl phosphonic acids,i, e. 2-phosphonobutane-1,2,4-tricarboxylic acid （ PBTCA ）, 1,2,2-triphosphonobutane-4-carboxylic acid （ TPBCA ）, 3,3-diphosphonopentane-1,5-dicarboxylic acid （ DPPDCA） ,were studied systemically by using Density Functional Theory （DFT） method at B3LYP/6-31G ＊ level. Results of quantum chemical calculations indicated that carboxylic oxygen and phosphonate oxygen atoms in these molecules had more negative charges,which caused that electrostatic interactions between oxygen atoms and calcium cations on the calcite cystal surface. If the distances between oxygen atoms and neighbouring calcium cations are matched,which induced crystal lattice aberration to inhibit crystal growth efficiently. That is the results of corrosion inhibition capability of these molecules, PBTCA 〉 DPPDCA 〉 TPBCA. In this paper,carboxylic oxygen and phosphonate oxygen atoms which afford the important contribution to molecule＇ s corrosion inhibition capability were received.