Synthesis Of A New Reagent 5-p-methoxyphenylazosalicylfluorone And Study On Application Of Green Extraction System

Research new methods on determination of trace rare metals with better sensitivity and development of rare metals with green extaction system on metallurgy industry are very important increasingly. Based on the consideration of the relationship of the structure of phenylfluorone reagents and their analytical characteristics, a new reagent, 5-p-methoxyphenylazosalicylfluorone (p-MOPASF), was designed and synthesized in this laboratory. Firstly, element analysis was applied to confirm the intermediate of 5-p-methoxyphenylazosalicylaldehyde. The 5-p-methoxyphenylazosalicylaldehyde reacted with 1,2,4-triacetoxybenzene and then p-MOPASF can be obtained by condensation and the product ratio can be up to 41%. After purified, the molecular structure of the reagent was confirmed by ultraviolet spectrum (UV), infrared spectrum (IR) and EIS-/EIS+. The green process route with ionic liquid was developed and 1-octyl-3-methyl-imidazolium hexafluorophosphate ionic liquid was also synthesized successfully.Molybdenum, tungsten, germanium, gallium and indium were choiced as representatives of rare metals. Firstly, we investigated color reaction of p-MOPASF with molybdenum tungsten, germanium, gallium and indium, respectively. In the presence of sulfuric acid and CTMAB, p-MOPASF reacted with molybdenum and tungsten rapidly to form 3:1 orange complex with the maximum absorption peaks at 526nm and 519nm, respectively. The apparent molar absorptivity were found to be 1.43×105L·mol-1·cm-1 and 1.36×105L·mol-1·cm-1, respectively. Beer's law is obeyed in the range of 0~15μg/25mL and 0~30μg/25mL for molybdenum and tungsten, respectively. Furthermore, we also studied the color reaction of p-MOPASF with germanium. In the presence of phosphate acid and OP, p-MOPASF reacted with germanium rapidly to form 3:1 orange complex with the maximum absorption peak at 507nm. The apparent molar absorptivity was found to be 1.44×105L·mol-1·cm-1. Beer's law is obeyed in the range of 0~2.5μg/25mL for germanium. Moreover, on the basis of above color reaction between p-MOPASF and rare metal ions, we studied the color reaction of p-MOPASF with gallium and indium. In the presence of NaAc-HAc buffer solution and CTMAB, p-MOPASF reacted with gallium and indium rapidly to form 3:1 red complex with the maximum absorption peaks at 558nm and 559nm, respectively. The apparent molar absorptivity were found to be 1.23×105L·mol-1·cm-1 and 1.68×105L·mol-1·cm-1, respectively. Beer's law is obeyed in the range of 0~10μg/25mL for gallium and indium. Based on the above datas, 5-p-methoxyphenylazosalicylfluorone is a new chelator and can be employed on rare metals on analysis and on metallurgy industry.Although color reaction of p-MOPASF with rare metal ions have high sensitivity, the methods are not good enough to determine ultra trace Mo, W, Ge, Ga and In in complicated samples. In order to advance the sensitivity further more, room temperature ionic liquid was used to replace traditional volatile organic reagents in liquid-liquid extraction of molybdenum, tungsten, germanium, gallium and indium. 1-octyl-3-methylimidazolium hexafluorophosphate [C8mim][PF6] with high extraction efficiency was chosen as medium. After the complex of molybdenum, tungsten, germanium, gallium and indium with p-MOPASF were formed in optimal conditions in 1000mL calibrated bottle, 5mL [C8mim][PF6] were added into the solution and the complex were extracted to ionic liquid phase after 5 minutes'surge. A certain volume of acetone and some amount of activated carbon were added into the ionic liquid phase with 5 minutes'surge. The complex was back-extracted by 4.0mol/LNaOH solution and then molybdenum, tungsten, germanium, gallium and indium in water phase were determined by spectrophotometry. We focused on the extraction system of molybdenum, and the method was chosen and applied to determine ultra trace molybdenum in environmental water samples. Combined by graphite furnace atomic absorption spectrometry, both the extraction efficiency and stripping efficiency were very high, and the results are satisfying. Ionic liquids are"green reagents". In order to avoid environmental pollution caused by organic reagents'volatilization, they can be used to replace traditional organic reagents in hydrometallurgy. Furthermore, the extraction system of germanium was also studied and the system was suitable to enrich germanium from simulated hydrometallurgical zinc electrolyte. It is proved that the results are satisfying.