Solubility Measurement Study on a Metastable Polymorph of β-2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane by Raman Spectroscopy

Abstract

Raman spectroscopy was used to measure the solubility of the metastable form of β-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (β-HNIW) in organic binary solvent mixtures. The distinct Raman spectra peaks of the solid, solute, solution, and solvent were investigated. Peaks that were not overlapping each other were used to develop a calibration curve. Then, linear relationships between solution concentration and Raman intensity were used to measure the solubility of β-HNIW in binary solvent mixtures during the dissolving process. The solubility of β-HNIW in binary solvent mixtures (ethyl acetate + n-hetpane, ethyl acetate + 1,1,2-trichloroethane, ethyl acetate + cyclohexane, ethyl acetate + toluene, ethyl acetate + diethyl ether, and ethyl acetate + petroleum ether) was investigated. The temperature ranged from 283.15 K to 333.15 K at atmospheric pressure. The solubility of β-HNIW in binary solvent mixtures decreases with increasing temperature. In order to correlate the solubility of β-HNIW, the combined nearly ideal binary solvent/Redlich–Kister (CNIBS/R-K) model and Jouyban–Acree model were employed. The Jouyban–Acree model is in better agreement with experimental solubility for all of the binary solvent mixtures. The average relative error is less than 0.05. Dissolution enthalpy and entropy were determined using the van’t Hoff equation.

Effect of ethyl acetate on crystal quality of HMX in the acetone

“…The ethyl acetate has bands at 377.1, 632.92, 847.39, 1453.91, 1735.82, 2941.82 cm -1 . Compared with literature [16][17][18][19][20] , the Raman spectra of acetone and ethyl acetate show the same Raman feature at 785.5, 1432.9, 1711.7, 2918.9 cm -1 [18] and 377, 632, 846, 1451, 1736, 2939cm -1 [19] , respectively. Comparing the Raman spectra of HMX-1 and acetone shown in Figure 6, it is shown that there are no characteristic peaks of acetone was found in the HMX spectrum, which indicates that no residual acetone in the obtained HMX-1.…”

“…Approximate type of mode [18] Acetone Raman Shift (cm -1 ) Reference Data (cm -1 ) [18] 107.52 Approximate type of mode [20] Ethyl Acetate Raman Shift (cm -1 ) Reference Data (cm -1 ) [20] C-C bending 377. 6.…”

Thermodynamic Study on the Amorphous Form and Crystalline Hydrates Using in Situ Raman and FBRM

“…During the measurement of the polymorph solubility, the crystalline form of the residual solid can undergo transformation. A phase transition of the metastable form in the solution phase may occur during the solubility measurement process [15,21]. The solubility of the metastable form cannot be measured by an off-line method.…”

“…The residual solid in the solubility measurement and analysis might be transformed. Therefore, in situ measurement techniques are desirable because it is difficult to monitor the metastable form with an off-line analysis [15][16][17]. In this study, a focused beam reflectance measurement (FBRM) probe and a Raman spectroscope were mounted on-line to measure the crystal size, the number of particles, the polymorph difference, and the solubility, simultaneously.…”

Measurement and Correlation of Solubilities of γ-2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (γ-CL-20) in Six Pure Solvents and Four Different Chloralkane + Ethyl Acetate Binary Solvents from 283.15 to 323.15 K

“…the solvents used in the transcrystallization process should be environmentally friendly, have good thermal properties, and be noncorrosive and readily available. Based on the literature, , related to the crystallization of γ-CL-20, the rule of the likes dissolves each other and the common organic solvents in the industry or laboratory. Solvents such as ethyl acetate, methanol, ethanol, n -propanol, n -butanol, dichloromethane 1,2-dichloroethane, chloroform, and tetrachloromethane were selected in this work.…”