Jie Zhang,Ningyu Chen,Yuheng Cui,Liqun Zhang,Dongmei Yue
In this study, novel 1-methylpropargyl alcohol derivatives containing leucine side groups on their side chains were successfully synthesized and polymerized using (nbd)Rh + [η 6 -C 6 H 5 B − (C 6 H 5 ) 3 ] as catalyst. Circular dichroism (CD) and ultraviolet–visible (UV–Vis) spectra revealed that the polymers took predominantly one-handed helical structures that were stable under heat. Deprotection of the t-butyloxycarboryl (Boc) groups in the homopolymers under acidic conditions produced polymers with primary amine moieties on the side chains. The polymers were soluble in aqueous medium, and turbidity test revealed that they were pH-responsive. Amino acid-based polymers were further used in the enantionselective crystallization of alanine enantiomers and l -alanine was preferably induced to crystallize with the l -leucine-based polymer.
Tianhua Huang,Dingqiang Lu,Xiuquan Ling,Xinxian Wang,Tongqi Liu,Fangfang Shen,Kefei He
In this paper, we focused on solubility and solution thermodynamics of istradefylline. Herein, we investigated the solubility and solution thermodynamics of istradefylline in binary solvent mixtures by gravimetric method. The solubility of istradefylline in (ethyl acetate + isopropanol), (ethyl acetate + tetrahydrofuran) and (ethyl acetate + acetone) was measured in the temperature range of 278.15 K–333.15 K under atmospheric pressure. In order to correlate the solubility of istradefylline, we employed the modified Apelblat equation, general cosolvency model and Jouyban-Acree model. Computational results showed that the modified Apelblat equation and general cosolvency model have low mean deviation. As calculated by van’t Hoff equation, the values of thermodynamic properties such as Gibbs energy, enthalpy, and entropy proved that the dissolution process is endothermic.
Yang Song,Zhihui Cai,Zhixian Li,Guoqiang Guan,Yanbin Jiang
Crystallization is one of the most important unit operations in the quality control of pharmaceutical products. For this study, a polymer-induced heteronucleation method was selected to investigate the effect of nylon 66 (PA66), polyester (PET), and polypropylene (PP) films on the crystal growth of paracetamol by coupling experiments with modeling. The result of induction time indicated that the order of induced effect was PA66 > PET > PP > no template. X-ray photoelectron spectroscopy results indicated the different functional groups on the surface of films. The crystal habits and powder X-ray diffraction results indicated that preferential orientation along certain facets occurred for PA66 and PET, and the results of in situ Raman microscopy verified the different concentration trends near different films, which is consistent with the preferential orientation effect of films. The results of molecular simulation indicated that the difference in van der Waals and electrostatic interaction, as well as H-bond donor/acceptor on the polymer films, is the origin of the preferential orientation effect for paracetamol crystallization. The PP film modified with similar functional groups of PA66 on surfaces caused the same preferential orientation effect as PA66, which verified the functional-induced mechanism of the preferential orientation. This study could contribute to the investigation of the mechanism of polymer-induced heteronucleation and screen out the efficient templates.
Yumei Kai,Yonghong Hu,Zheng Cao,Xiang Liu,Yan Liu,Wenge Yang
The solubilities of l -malic acid in pure and mixture organic solvents were measured from 278.15 to 323.15 K using the laser monitoring observation system. The modified Apelblat equation, the semi-empirical Buchowski–Ksiazczak λh equation and the Combined Nearly Ideal Binary Solvent/Redlich (CNIBS/R-K) equation were proposed to correlate the experimental data. In pure and mixed solvents, the 100RD (relative deviation) <3.61 and 7.58, respectively, the 10 4 RMSD (root-mean-square deviations) <3.07 and 2.28, respectively, so the equations selected in this work fit the data very well. Van’t Hoff equation was used to predict the dissolution enthalpy and entropy of l -malic acid in the corresponding solvents.
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