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ABSTRACT: The molecular interactions in the complex formation of two tartaric acid derivatives with di(2-ethylhexyl) phosphoric acid
are investigated. The complex formation with a 1:1 stoichiometry between tartaric acid derivatives and D2EHPA can be obtained
through UV-Vis titration, NMR chemical shifts and molecular dynamic simulations. Furthermore, the differences of the two complexes
on the binding constants and strength of hydrogen bonds can also be determined. Such research will ideally provide insight
into ways of regulating the complex forming properties of tartaric acid derivatives for composing or synthesizing new chiral
resolving agents.
Science in China Series B Chemistry 04/2012; 51(9):887-892. · 1.20 Impact Factor
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ABSTRACT: The paper presents a new complex chiral selector of di(2-ethylhexyl)phosphoric acid (D2EHPA) and O,O′-dibenzoyl-(2R,3R)-tartaric acid ((−)-DBTA) and its enantioselectivity on d,l-tryptophan (Trp). The influence of the initial concentration of d,l-Trp, (−)-DBTA, D2EHPA were studied. Both the distribution ratio and enantioselectivity of d,l-Trp are greatly improved with the complex extractant instead of (−)-DBTA individually. It was also found that the enantioselectivity of the complex extractant was changed by the D2EHPA content, although pure D2EHPA has no chiral separation ability. By adjusting the equilibrium pH in the aqueous phase, a high chiral separation efficiency with a maximum enantioselectivity of 5.3 and an enantiomeric excess (e.e.) of up to 57% in aqueous phase were reached at PI point. Finally, the most reasonable extraction mechanisms of the complex to Trp enantiomers have been suggested.
Separation and Purification Technology.
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ABSTRACT: It is well known that the droplet behavior of the dispersed phase in extraction equipments has a strong influence on the mass transfer performances. It is, and will continuously be a key project for design and scaling up of extraction columns. In this work, a dynamic mass transfer model, considering the effect of forward mixing led by the drop size distribution and the axial mixing of the continuous phase, has been developed, by which the axial mixing characteristic can be easily evaluated when a stimulus–response dynamic curve is obtained. In order to test the mass transfer model and to study in the effect of droplet coalescence on mass transfer performance, a typical experimental system of 30% tributyl phosphate (in kerosene)-nitric acid-water with interface intension of 0.00995 N/m was chosen to investigate the mass transfer in a coalescence–dispersion pulsed-sieve-plate extraction column (CDPSEC) with 150 mm in diameter. The two-point dynamic method was applied to get the stimulus–response curves. With these results the axial mixing of the CDPSEC were evaluated. The calculated results showed that the response curves could be predicted with the new mass transfer model very well. The model has marked advantages over the traditional diffusion model. It is closer to the practice, easier to solve for the mathematical equations and boundary conditions, and has only one parameter to be optimized. The calculated results also showed that the influence of local coalescence of droplets on mass transfer performances is obvious.
Chemical Engineering Science.
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ABSTRACT: In this paper, a new method to synthesize BaSO4 nano-particles in O/W system with filtration dispersion technology was developed. The nano-particles of barium sulfate were prepared using a type of filtration dispersion device with a plate porous disc as a dispersion medium. Working systems of barium chloride aqueous solution/30% TBP (in kerosene) with sulfuric acid were applied. The influence of the reactant concentration and the operation conditions were investigated. The morphology of the particles was observed by SEM, and the particle-size distributions were measured. The nano-particles prepared in O/W system were compared with those prepared by dispersing aqueous barium chloride solution into aqueous sodium sulfate solution with the same filtration dispersion device. The results showed that mono-dispersed BaSO4 particles can be prepared using the filtration dispersion method in O/W systems. The surfaces of all the particles were smooth. The mean diameter of the particles was in the 100–400 nm range and decreased with the increase of flux of the two phases. The ratio of the two phases greatly affects the morphology of particles because of the excess concentration of [SO42−]. The particle size was also much smaller when the mixed two feeds were aqueous solutions.
Powder Technology. 153(2):90-94.
