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In this study, the saturated solubility of triethylamine hydrochloride (TEA·HCl) was determined using the static method in binary mixed solvents ((1-Butanol, dimethyl sulfoxide (DMSO), 1-Octanol) + dimethyl carbonate (DMC)) at temperatures ranging from 298.15 to 333.15 K and ambient pressure (p = 0.1 MPa). Quantum chemistry calculations were performed to analyze the dissolution process among different solvents. Results showed that the obtained solubility data correlated well with five equations. Evaluation of solubility data was carried out by mean Average Relative Deviation (ARD) and Root-Mean-Square Deviation (RMSD). The findings indicated that the modified Apelblat model demonstrated the strongest correlation among the five models. The ARD and 104 RMSD were 1.39% and 2.61, respectively. Subsequently, the Gibbs energy, enthalpy, and entropy of TEA·HCl dissolved in each mixed solvent can be determined by applying van't Hoff equations, revealing an endothermic and entropy-driven dissolution process. The experimental results indicated that the solubility of TEA·HCl in the selected binary solvents increased with the increasing temperature and decreased with the increasing molar fraction of DMC. The solubility sequence in various systems was explained in terms of the solvation free energy. The solubility values, model parameters, and thermodynamic properties of TEA·HCl in different mixed solvents can be obtained through experimentation, providing foundational support for its preparation, crystallization process, and further theoretical research. [ABSTRACT FROM AUTHOR]

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For the preparation of an immobilized DMAP derivative, 4-dimethyl-aminopyridine (DMAP) is covalently bonded to the surface of nanoscale silicon dioxide by N-alkylation. The immobilized DMAP derivative is first introduced as a catalyst to produce monomenthyl succinate in a mixed solvent system consisting of cyclohexane/acetone (3:2, v/v). The activity of this immobilized DMAP derivative reaches $0.148~\mathrm{mol}_{\mathrm{product}}/\mathrm{mol}_{\mathrm{DMAP}} {\cdot }\mathrm{h}$ and the highest yield of monomenthyl succinate reaches 91.78%. The recyclability and stability of the immobilized DMAP derivative are excellent as demonstrated by its use 10 times during the recycling operation without obvious loss of productivity. This is an efficient heterogeneous catalyst, which can prevent catalyst contamination of the product. In addition, immobilization provides a possibility for continuous production by the use of a packed-bed reactor. Excellent results are obtained, which make the nanoscale silicon dioxide immobilized DMAP derivative a more promising candidate for the industrial production of monomenthyl succinate.

Catalytic efficiency in synthesis of vitamin E succinate was dramatically increased via the preparation of robust catalyst and the improvement of reaction system. 4-dimethylaminopyridine (DMAP) was covalently immobilized on nano-SiO2 to avoid the catalyst contamination of the product and permit the easy recycling of DMAP. Then, a hexane-acetone mixed solvent system was firstly introduced to replace the traditional single-solvent system, which was employed to improve the activity of immobilized DMAP derivative and the substrate solubility of the reaction system. The highest vitamin E succinate yield of 94% was achieved. In addition, the recyclability and stability of the immobilized DMAP derivative was excellent, the yield of vitamin E succinate had no obvious loss and remained 90% after recycling 20 times. The excellent results make this technology be a promising candidate for the industrial production of vitamin E succinate.

Analysis of lubricating oils and their additives for Ni, Zn, Mg and Ca was carried out by the proposed method using benzene-acetic acid/methyl isobutyl ketone (MIBK) mixed solvent system. Flame atomic absorption spectrometry using air-acetylene flame was employed with the incorporation of concentrated hydrochloric acid into the solvent mixture. The large dilution of samples employed due to flexible working range of this procedure eliminates the need for matched standard hence the same standards are adequate for all types of lubricating oil samples and additives. No effect on the analysis arising from varying viscosities of the oil samples was observed. Results obtained for a wide range of lubricating oils and automatic transmission fluids revealed good agreement with those obtained by established ASTM chemical procedure.

Highlights: [•] Epirubicin-loaded nanoparticles were prepared in organic/aqueous solvent system. [•] Epirubicin loading affected the size and the zeta-potential of the obtained particles. [•] Drug loading was found to depend on the initial drug concentration. [•] Epirubicin was found to be tightly associated with the particles. [•] Epirubicin loading resulted in the formation of polymer with increased molecular mass. [Copyright &y& Elsevier]

Abstract: The separation of acetone and ethanol binary mixture derived from the fermentation broth using pervaporation membranes is very challenging, most likely due to their small molecular size differences. In addition, the characteristics of acetone as a strong solvent which can easily swell and dissolve polymer materials, further increases the difficulty of separation. Flat asymmetric PVDF membranes with strong chemical resistance and good mechanical strength fabricated via mixed solvent systems show a great potential for the aforementioned binary separation via pervaporation. A mixed solvent system (50/50wt%), i.e. NMP/THF or NMP/Acetone, coupled with the evaporation of volatile latent solvent at elevated temperatures, i.e. 40–100°C, has effectively suppressed macrovoids and promoted dense skin layer formation in PVDF membranes as compared to that of pure NMP system. By altering the demixing process at selected evaporation temperatures, i.e. 60–80°C, the pore structure of membranes cast from mixed solvent systems can be further designed into the desired interconnected open pore structure rather than globular structure with weaker mechanical strengths. From the trade-off line of acetone/ethanol separation via pervaporation, it can be revealed that PVDF membranes cast from mixed solvent systems at higher evaporation temperatures, i.e. 60–100°C, exhibit superior separation factors (up to 4) with reasonably high fluxes (1–4kg/m2 h) as compared to those of pure NMP system. This separation performance is comparable or higher than that of commercially available PDMS membranes. [Copyright &y& Elsevier]

Direct and indirect oxidation of 1,5-diphenylcarbazide have been studied at hanging mercury drop electrode with differential pulse voltammetric technique. Direct oxidation of 1,5- diphenylcarbazide with KMnO4 resulted in formation of 1,5-diphenylcarbazone in the system at the reduction potential of -0.3 Volts. Oxidation study with K2 Cr2 O7 resulted in formation of 1,5-diphenylcarbazone at the reduction potential of -0.3 Volts along with formation of 1,5-diphenylcarbadiazone at the reduction potential of -0.6Volts in the system. Thus indicates that KMnO4 can be utilized for controlled step oxidation of 1,5-diphenylcarbazide, whereas, K2 Cr2 O7 can be utilized for maximum oxidation of 1,5-diphenylcarbazide. Indirect oxidation of 1,5-diphenylcarbazide was studied by dissolving 1,5-diphenylcarbazide in water mixed solvent systems for aerial oxidation due to formation of 1,5-diphenylcarbazone occurred and detected at the reduction potential of -0.3Volts. [ABSTRACT FROM AUTHOR]