On the Tributylphosphate-Based Super-Concentrated HCl System
GUO Lin1, 2, HUANG Kun3, GUO Ran2, HE An-qi2, WENG Shi-fu2, YANG Zhan-lan2, ZHAO Ying4, XIA Jin-ming5, XU Yi-zhuang2*, KANG Ting-guo1*，WU Jin-guang2
1. College of Pharmacy, Liaoning University of Traditional Chinese Medicine, Dalian 116600, China 2. Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China 3. Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China 4. Beijing National Laboratory for Molecular Sciences, Key Laboratory of Engineering Plastic, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China 5. Shenyang Dootel Biopharmaceutical Research Center, Shenyang 110031, China
Abstract：We reported a new super-concentrated hydrochloric acid system prepared by using tri-n-butyl phosphate (TBP)-constructed reversed micelles at ambient temperature and pressure. According to the titration result, the molar ratio of H+ to H2O (denoted as nH+/nH2O) in the super-concentrated HCl range from 0.50 to 1.50 which are higher than that in saturated aqueous HCl bulk solution (0.28). Significant a moment of hydrochloric acid is confined in W/O reversed micelles. Therefore, the behavior and status of HCl are different from those of conventional bluk solution. FTIR spectroscopic results demonstrate that a significant amount of HCl remains in the molecular form rather than being ionized into H+ and Cl-. Thus, super-concentrated HCl provides an extraordinary chemical environment which may have significant influence on certain substances. We found that the color of the solution is reddish brown when copper ion is dissolved in super-concentrated HCl, while the color of the saturated HCl aqueous solution (37 Wt%) containing copper ion is green. That is to say, the copper ions exist in a special state under the unique chemical environment of super-concentrated HCl. UV-Vis-NIR spectra indicate that both d-d transition band and charge transfer transition band of copper ions in super-concentrated HCl solution underwent significant variations. In addition, copper ions also have obvious influence on the hydrogen bond network among HCl in the super-concentrated HCl solution. Remarkable variation is introduced in the H—Cl stretching band in FTIR spectra.
Key words：Tributyl phosphate (TBP);Super-concentrated HCl;nH+/nH2O;Copper ion
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