Xin Jin,Sen Huang,Fan Wang,Lin Zhu,Hongbing Song,Congxia Xie,Shitao Yu,Shumei Li
2,2′-Bis(diphenylphosphino)-1,1′-binaphthyl (BINAP) is a widely used chiral phosphine ligand, and the sulfonated BINAP is one of the important water-soluble BINAP derivatives. In this article, we report an improved oleum sulfonation method for the synthesis of the high-purity 5,5′-disulfonato-( S )-BINAP ligand with an industrially acceptable high yield. By optimizing the sulfonation conditions and improving the workup process, the yield of 5,5′-disulfonated products was enhanced to 73 %. Furthermore, an acetonitrile extraction protocol was developed for the purification of sulfonated products by efficiently removing phosphine oxides, by which the content of phosphine oxide can be controlled below 3 %. The structure of 5,5′-disulfonato-( S )-BINAP was characterized with the elemental analysis, FT-IR, 1 H NMR, 13 C NMR, 31 P NMR, 1 H- 1 H COSY, 1 H- 13 C HSQC, 1 H- 13 C HMBC, and HR-MS, which unambiguously confirmed that the sulfo groups are introduced at the 5,5′-position of the binaphthyl ring skeleton in ( S )-BINAP. The prepared high-purity 5,5′-disulfonato-( S )-BINAP was evaluated in the Ru-catalyzed asymmetric hydrogenation of β -keto esters, which exhibited high catalytic activity, enantioselectivity and excellent catalytic stability.
Reduced graphene oxide nanofiber (rGONF) modified by anthraquinone-1,5-disulfonate (AQDS) (AQDS-rGONF) was prepared by one-step hydrothermal reaction , and nanocilia-like polyaniline (PANI) grew uniformly on the surface of rGONF under the guidance of AQDS as a starting point of polymerization to fabricate successfully PANI/AQDS-rGONF composite. The results showed that PANI/AQDS-rGONF composite had a larger specific capacitance of 511 F/g than PANI/rGONF composite of 360 F/g or PANI of 312 F/g at a current density of 8 mA/cm 2 , and a greater electrochemical stability with the specific capacitance retention of 82.4% than PANI/rGONF of 63.2% or PANI of 52.2% after 2000 cycles, which were closely related to the synergistic effects of special nanocilia-like structure, large specific surface area, rGONF as a supporting skeleton and AQDS as a “bridge”. In addition, an asymmetric supercapacitor based on PANI/AQDS-rGONF composite as cathode was assembled, which exhibited a high energy density of 17.9 Wh/kg at a power density of 907 W/kg.
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