红外光谱在线监控对二苯脲合成反应进程的研究

Monitoring the Synthesis of N,N-Diphenyl Urea by IR-Online

利用ReactIRTM4000实验室在线红外分析系统对脲和苯胺合成二苯脲反应进行在线监控,通过监测反应物脲(1 420 cm-1)和苯胺(1 270 cm-1)、中间产物苯基脲(1 339 cm-1)及产物二苯脲(1 312 cm-1)特征峰的变化,推断出反应体系中各组分浓度的变化,从而清楚地了解了该反应的进程。研究的结果证明脲和苯胺合成二苯脲的过程是脲和苯胺先生成中间产物苯基脲,苯基脲再和苯胺生成二苯脲。结果表明在线红外分析能够快速、简便、准确地确定出反应的最佳时间,从而达到对合成反应的进程进行控制的目的。

IR-online detector, React IRTM 4000, was used to monitor the synthesis of N,N-diphenyl urea from urea and aniline. The concentration changes of the reaction components were obtained according to the characteristic IR absorbanee changes of the reactants （urea and aniline） at 1 420 and 1 270 cm^-1 respectively, the !intermediate product （monophenylurea） at 1 339 cm^-1 as well as the product （N,N-diphenyl urea） at 1 312 cm^-1. In the present study, the result showed that the synthesis of N,N-Diphenyl urea was carried out by two steps. Firstly, the intermediate product monophenylurea was synthesized from urea and aniline, and then N, N-diphenyl urea was obtained by the reaction of monophenylurea with aniline. It was also shown that the IR- online detector was a fast, simple and exact technique to optimize the reaction time and so the reaction course could be easily controlled. The result of IR-online spectrometry was approved by offline reference high performance liquid chromatography （HPLC） method. As a result, the IR-online spectrometry was superior to HPLC method since it was a nondestructive method without the need to sample the reaction medium.