中红外光纤光谱法在化学反应过程中的应用

Application of FT-mid-IR Fiber Optics Technique in the Chemical Reaction

将傅里叶变换中红外光纤光谱技术分别用于液相反应体系和固液反应体系的在线监测.在液相反应体系中,监测了环烷酸皂化时形成微乳的过程,初步了解了皂化环烷酸时微乳液的形成机制;在固液反应体系中,监测了邻苯二甲酸与氯化铕的配位反应过程,探索了络合物的生成过程及组分间的相互作用.该技术有望发展成为一种实时监测化学反应过程的新方法.

Fourier transform infrared （FTIR） spectroscopy is a sensitive probe of molecular structure which can provide significant information on the structure and composition of unknown substances and confirm the presence of some chemical groups. IR fiber optics possesses high performance which can be applied to transmission of IR light. The coupled technique of FTIR and mid-IR fiber optics can simplify the sample preparation in traditional IR spectroscopy. Formation of new compound is observed in situ and reaction process can be monitored on line using FTIR fiber optics technique. In this study, mid-IR fiber optics technique was applied to liquid phase systems and solid/liquid reaction systems. In the liquid phase system, we investigated the saponification reaction of naphthenic acid-octal alcohol-heptane and the formation mechanism of water in oil（w/o） mieroemulsion during saponification. The interaction between naphthenic acid and octal alcohol was observed. With adding ammonium hydroxide, the peak around 1708 cm-1 disappeared and the peak at 1548 cm-1 enhanced and the peak position of water emerged and shifted to 1637 cm-1 from 1642 cm-1 , which is the position of water molecule in IR spectroscopy. It showed that water is constrained in aqueous droplet of naphthenic acid-octal alcohol-heptane and microemulsion is formed through the saponification. In the solid/liquid reaction system, complexation reaction between o-phthalic acid and europium chloride was investigated. The interaction between o-phthalic acid and EuC13 in neural medium was ignored in previous study, but this weak interaction was observed using FTIR fiber optics technique in our present investigation. The results showed that the component and structure of the final complex were effect by the difference of adding sequence. Therefore, FTIR fiber optics technique may become a new method of monitoring chemical reaction in real time.