在线红外光谱研究乌洛托品成盐机理

为了解乌洛托品(HA)和硝酸(NA)体系的成盐反应过程,明确成盐机理,采用在线红外技术跟踪监测分析了HA与NA生成乌洛托品一硝酸盐(HAMN)和乌洛托品二硝酸盐(HADN)过程中主要官能团特征吸收峰随时间的变化,用计算化学方法研究了HA与NA之间的相互作用。结果表明,在HA的成盐过程中,HNO_3与HA生成HAMN的反应很快,而HAMN到HADN的反应相对较慢。当硝酸达到5.97 mol·L~(-1)时,才有HADN生成。在HAMN红外光谱中,1002,1236,690,806 cm_(-1)处出现了颠倒峰,这些峰为HA中C—N键的特征吸收峰。由于生成了HAMN,引起了C—N键的力常数的改变,在倒峰左右两边对应处出现了波数为979,1024,1219,1259 cm~(-1)的吸收峰。当有HADN析出时,不滴加硝酸,依然有HADN生成并析出,且溶液中硝酸的量呈现缓慢上升趋势。在HAMN生成在过程中,HAMN吸附了周围的硝酸分子,当有HADN生成时,释放硝酸分子到溶液中,供给HAMN分子继续反应生成新的HADN分子。用高斯软件得到了HA和NA、HA与H_2O的优化结构和计算结合能值,显示HA的硝酸体系更稳定,该结果与实验结果一致。

Salt Formation Mechanism of Urotropine by On-line Infrared Spectroscopy

To understand the salt-forming reaction process of urotropine(HA) and nitric acid (NA) system and clear the salt-forming mechanism, the change in characteristic absorption peak of main fuctional groups with time in the process of forming mononitrate of HA (HAMN) and dinitrate of HA (HADN) was tracked, monitored and analyzed by on-line infrared spectroscopy technology and the interaction between HA and NA was studied by computational chemistry method.Results show that in the salt-forming process of HA, the reaction of forming HAMN by NA with HA is quick, but the reaction of HAMN to HADN is relatively low.When NA reachs 5.97 mol·L-1, HADN is only formed.In the IR spectra of HAMN, the inverted peaks appear at 1002, 1236, 690, 806 cm-1, which are the characteristic absorpption peak of C-N bond in HA.Due to the HAMN is formed, the C-N bond force constant of HA is changed, the absorption peaks at 979, 1024, 1219 cm-1 and 1259 cm-1 were appeared on the left and right sides of the inverted peak.When there is HADN precipitation, without adding NA, there are still HADN formation and precipitation and the amount of NA in the solution shows a slow upward trend.In the process of HAMN formation, HAMN adsorbs the NA molecules around it.When the HADN is formed, the NA molecules are released into the solution, and the HAMN molecules are supplied to continue to form new HADN molecule.The optimized structure of HA and NA, HA and H2O obtained by Gaussian software and calculated binding energy values are obtained, revealling that the NA system of HA is more stable.The results are in agreement with the experimental ones.