Five novel CL-20 solvates were prepared and fully characterized, and the solvate formation and phase transformation processes were systematically investigated.

In this work, pure form I and form II of furosemide-4,4'-bipyridine (FS-4BPY) 2:1 cocrystals were prepared. Both polymorphs were characterized by optical microscopy, powder X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, and Fourier transform infrared spectroscopy. The relative stability of the two forms was estimated from their solubility data in 2-propanol by the gravimetric method. Moreover, the thermodynamically stable form with lower solubility, form II, was further investigated in different pure and binary solvents from 293.15 K to 333.15 K under atmospheric pressure. In pure solvent system, the solubilities of forms II cocrystals increase with rising temperature and follow the order of acetone > ethanol > 1-propanol approximate to 1-butanol > 2-propanol > acetonitrile. In 2-propanol-water binary solvent system, the co-solvency phenomenon was observed and the maximum solubility of form II is higher than that in pure solvents. The experimental solubility data were correlated by the modified Apelblat model, the CNIBS/R-K model, the Jouyban-Acree model and the NRTL model, and all models give satisfactory correlations. Finally, the apparent dissolution thermodynamic properties, including the dissolution Gibbs energy, the dissolution enthalpy and the dissolution entropy, were calculated based on the NRTL model. The results indicate that the dissolution processes of form I and form II of FS-4BPY cocrystals in selected solvents are all spontaneous, endothermic, and entropy-driven. (C) 2019 Elsevier B.V. All rights reserved.

Solubility of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) acetonitrile solvate and form epsilon in acetonitrile + trichloromethane, acetonitrile + dichloromethane, and acetonitrile + 1,2-dichloroethane binary solvent mixtures was experimentally determined from 298.15 K to 313.15 K under 0.1 MPa using isothermal gravimetrical method. The thermodynamic relationship between acetonitrile solvate and form epsilon was confirmed by polymorphic transformation experiment, and the equilibrium mole fraction of acetonitrile x(2),(L)(T) that corresponded to the transformation between acetonitrile solvate and form epsilon was obtained simultaneously. The ternary phase diagrams of CL-20-acetonitrile-trichloromethane, CL-20-acetonitrile-dichloromethane, and CL-20-acetonitrile-1,2-dichloroethane systems were established to give deeper insights into the phase behaviors of CL-20. The effect of temperature on the formation of CL-20 acetonitrile solvate in different solvent systems was then investigated, the results of which demonstrate that the solvate formation could be suppressed by either increasing temperature or using different anti-solvents. Consequently, the phase behaviors of CL-20 in the suspension can be predicted and controlled exactly to obtain the desired product during the crystallization process. (C) 2019 Elsevier B.V. All rights reserved.

In this article, the plantwide control of a novel process for diethyl oxalate production via two steps is investigated. The unique feature of this process is that there is a closed regeneration-coupling circulation. It results in that two steps should be matched properly and mass balance for overall reaction should be satisfied precisely. An effective control structure using a feedforward ratio with composition controller is determined. Later, safety analysis for this process is investigated by the integration of dynamic simulation and HAZOP (hazard and operability analysis). In comparison with heuristic HAZOP, quantitative deviations can be introduced. Quantitative variation trends and change rates of important variables can be determined. Determining increase rate in temperature and pressure is significantly important, since response time as indirect indictor can be used to assess the possibility of risk. Finally, a general procedure based on simulation for design and safety analysis of chemical process is proposed. (C) 2018 Elsevier Ltd. All rights reserved.

The crystal structure, thermodynamic phase diagram, and polymorphic transformation behaviors of CL-20 acetonitrile solvate are systematically investigated.

The solution-mediated polymorphic transformation (SMPT) of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) from form β to form ε was investigated in ethyl acetate-chloroform mixed solvent. The transformation process was revealed by using on-line tools including attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and in-situ Raman spectroscopy combined with off-line analysis of the solid phase using optical microscopy and powder X-ray diffraction (PXRD). Thermodynamic driving force of the SMPT process was evaluated through solubility determination of the two forms. The results demonstrate that the SMPT process consists of three stages, which are the dissolution of form β, the nucleation and the growth of form ε, and the rate-determining step is the nucleation and growth of form ε. The transformation experiments were also performed under different solvent compositions, solid loadings, percentages of seeds and particle sizes of seeds to give deeper insights into the SMPT process. Besides, the transformation kinetics were further investigated by Avrami-Erofeev model to access the effect of temperature on the SMPT process. This study enriches the research of SMPT mechanism for CL-20 and provides a good guidance for obtaining particles with superior crystal form purity.

Compared with traditional hot air drying method, the existence of optimal material layer thickness is a significant phenomenon in microwave thin layer drying process. In the current work, a new initial temperature-based methodology is proposed to predict the optimal thickness and to evaluate the effect of influential factors on optimal thickness. The evaluated optimal material layer thickness by the proposed methodology is consistent with experimentally measured value, and hence confirms that the optimal layer thickness can be predicted exactly through the average temperature of bulk material at the initial 1st min during pre-heating stage. With the help of the proposed methodology, it is discovered that attenuation factor, beta, surface convective heat transfer coefficient, h, and environmental air temperature, T-e are the main factors that affect the optimal thickness. And a larger beta or T-e tends to result in a smaller optimal thickness, while the situation for h is just the opposite. These results can play a crucial role in designing apt continuous microwave tunnel drying system or aid in guiding their operations. (C) 2018 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

In this work, the dissolution mechanisms of detergent agglomerates with different binders were investigated in aqueous solution. The dissolution processes of detergent agglomerates were online monitored by using in situ UV-VIS spectrophotometer and electric conductivity probe. Dissolution profiles were correlated by Weibull model to evaluate the time-dependent dissolution rate coefficient and to classify the type of dissolution rate function k(t)(t). The Kullback-Leibler information distance d(K-L) was proposed to assess the degree of dissolution heterogeneity. The results indicate that the sodium linear alkylbenzene sulfonates (NaLAS) and sodium carbonates (Na2CO3) in detergent agglomerates have different dissolution behaviors, and their dissolution rates are influenced by the type and content of binders. Moreover, detergent agglomerates using semi-solid NaLAS paste or liquid linear alkylbenzene sulfonic acid (HLAS) as binders in granulation processes follow different dissolution mechanisms in water. (C) 2017 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

In this work, the dissolution behaviors of a series of sodium alkylbenzenesulfonates (NaLAS) tablets with different moisture contents and neutralization degrees were investigated in aqueous solution. The ANOVA-based, model-independent and model-dependent methods were employed to perform comparison analyses on dissolution profiles. The measurements of powder X-ray diffraction patterns and mechanical properties elucidate distinct differences in each formula. The results show that ANOVA provides a possibility for finding the source of differences among different variables, and the model-independent methods including the k values and mean dissolution time are easy to interpret and perform comparison analyses. The Hixson–Crowell model gives satisfactory correlation results for the dissolution data and the dissolution kinetics parameters are obtained. The inhibition effects of neutralization degree and moisture content on NaLAS dissolution were examined, which reveals that the increase in lamellar phase proportion leads to the reduction of dissolution rate. The comparison analyses performed in this work form part of a methodology for dissolution profile prediction and comparison.

Absolutely dried starch is widely used in cooking and other industries. However, the prolonged drying time during falling rate drying period and low energy efficiency limit the application of traditional hot air drying. Microwave energy is the alternative choice considering the 'volumetric heating' mechanism. Then, investigations on microwave thin layer drying of starch were conducted by experimental studies and mathematical modeling. Results show that drying time can be reduced significantly with the increase in microwave power density. And there exists an optimal layer thickness, both greater and less than the value will result in a lower drying rate. This phenomenon is completely different from hot air dying and has not been reported in literature before. Explanations are given from the perspective of heat and mass transfer. Data fitting shows that 'Midilli-Kucuk' model is the best one to describe drying behavior of starch. An integrated 'Midilli-Kucule model is also given after considering the effect of operating variables on model parameters. Effective diffusivities vary from 6.08 x 10(-7) to 6.10 x 10(-5) m(2)/s, and increase with the increase of microwave power density, decrease with the increase of surface area per unit mass, values are higher when compared with other materials dried under microwave in literature. Finally, nonlinear surface fitting was conducted in order to give a systematic prediction for effective diffusivities. (C) 2017 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Various methodologies have been proposed in literature on modeling microwave drying process. However, in these methodologies moisture diffusion is normally considered in the presence of intensive microwave energy. In the present study, a new theoretical model was developed to simulate microwave drying of thin layer particulate solids, based on the consideration that moisture diffusion along material layer could be ignored due to rapid evaporation under intensive microwave energy. The model was solved numerically by using finite difference method and validated against experimental data. Results indicated good agreement between the model and experimental data, thus providing confidence in the modeling approach. For the system investigated in this study, it was demonstrated that an 80% reduction in drying time was achieved with approximately fivefold increase in microwave power (109–543W). Furthermore, it was also demonstrated that the drying rate was the maximum corresponding to the optimal layer thickness in microwave thin layer drying process. Qualitative analysis explained the optimal thickness phenomenon using principles of heat and mass transfer. Finally, the validated model was used to predict moisture and temperature distributions along the entire material layer.

In this work, the solvent-mediated phase transformation of the metastable form (Form II) to the stable form (Form I) of ethenzamide-saccharin cocrystal in isopropanol was investigated. Solubility of Form I and Form II in pure isopropanol was also measured. The transformation mechanism from Form II to Form I was analyzed by some online and off-line tools including attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, Raman spectroscopy, and polarizing microscopy. The results demonstrate that the transformation process consists of three steps, involving the dissolution of Form II, the nucleation of Form I, and the following growth of Form I. The ATR-FTIR and Raman results show that the polymorphic transformation from Form II to Form I is controlled by the nucleation and growth of Form I. Furthermore, the microscope photographs clearly reveal that the Form I preferably nucleates and grows on the (100) surface of Form II. The molecular simulation results indicate that higher adsorption energy and the exposure of more activity groups make the molecule adsorbed more strongly on the (100) surface, which is in agreement with the experimental observation. The results drawn in this work will be of great significance to control the formation of a desired polymorphic final product of ethenzamide-saccharin cocrystal.

The solubility of ethenzamide in methanol, ethanol, 1-propanol, isobutanol, ethyl acetate and acetonitrile was determined via the gravimetric method in the temperature range from 288.15 K to 323.15 K at atmospheric pressure. Five thermodynamic models were employed to correlate the experimental solubility data. The correlated results were analyzed and compared with the experimental results. It was found that all the thermodynamic models give satisfactory correlation results, in which the modified Apelblat model shows the best fitting result. In addition, the molecular modeling studies were carried out to give the explanation for the sequence of solubility in various solvents. The dissolution enthalpy and entropy of ethenzamide were obtained by using the Van't Hoff equation. Furthermore, the mixing thermodynamic properties of ethenzamide, including the mixing Gibbs energy, the mixing enthalpy and entropy, as well as the infinite-dilution activity coefficient and the infinitesimal concentration reduced excess enthalpy, were also obtained by using the Wilson model and the experimental solubility values. (C) 2016 Elsevier B.V. All rights reserved.