|
| ||
|
|
||
Acetone Solvate (acetone + solvate)
Selected AbstractsThermal, phase transition and spectral studies in erythromycin pseudopolymorphs: dihydrate and acetone solvateCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2006Zhanzhong Wang Abstract The thermal, phase transition and spectral studies of erythromycin A dihydrate and acetone solvate were performed by Differential Scanning calorimetry (DSC), Thermo Gravimetry (TG-DTA), X-Ray Powder Diffraction (XRPD) and Fourier Transform Infra-Red (FTIR) spectrum. The non-thermal kinetic analysis of erythromycin A dihydrate was carried out by DSC at different heating rates in dynamic nitrogen atmosphere. The result showed that heating rate has substantial influence on the thermal behavior of erythromycin dihydrate. The Arrhenius parameters were estimated according to the Kissinger method. Corresponding to dehydration of dihydrate, melting of dehydrated dihydrate, phase transition from dehydrated dihydrate to anhydrate, and melting of anhydrate, the calculated activation energy were 39.60, 269.85, 261.23, and 582.16 kJmol,1, the pre-exponential factors were 3.46 × 103, 8.06 × 1032, 9.23 × 1030, and 7.29 × 1063 s,1, respectively. Ozawa method was used to compare activation energy values calculated by Kissinger method. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Polymorphism of racemic felodipine and the unusual series of solid solutions in the binary system of its enantiomersJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 7 2001Judith M. Rollinger Abstract The aim of this study was to investigate the binary phase diagram and the polymorphism and pseudopolymorphism of racemic and enantiomeric felodipine, including their spectroscopic and thermodynamic properties. Different crystal forms were obtained by crystallization from solvents or from the annealed melt and investigated by thermal analysis (hot stage microscopy, differential scanning calorimetry, thermogravimetric analysis), spectroscopic methods (Fourier transform infrared,and Fourier transform,Raman spectroscopy), and X-ray powder diffractometry. The binary melting phase diagram was constructed based on thermoanalytical investigations of quantitative mixtures of (+)- and (±)-felodipine. Two polymorphic forms of racemic felodipine, mod. I (mp, ,145°C) and mod. II (mp, ,135°C), as well as an acetone solvate (SAc,) were characterized. Melting equilibria of felodipine crystal forms decrease due to thermal decomposition. Enantiomeric felodipine was found to be dimorphic (En-mod. I: mp, ,144°C; En-mod. II: mp, ,133°C). Evaluation of the binary system of (+)- and (,)-felodipine results in the formation of a continuous series of mixed crystals between the thermodynamically stable and higher melting modifications, mod. I and En-mod. I. Their unusual curve course, termed as Roozeboom Type 2 b, passes through a maximum in the racemic mixture and is flanked by a minimum at 20% and at 80% (+)-felodipine. From the thermodynamic parameters, racemic mod. I and II are monotropically related. In contrast to SAc, the thermodynamically unstable mod. II shows a considerable kinetic stability. Because its crystallization is badly reproducible, the use of mod. II is not advisable for processing. However, desolvation of SAc leads to a profitable crystal shape of mod. I, representing a pseudoracemate by definition. © 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:949,959, 2001 [source] Bis(tetraphenylphosphonium) (hexasulfido-2,2S1,S6)di-,-sulfido-disulfido-1,2S -tungsten(VI)zinc(II) acetone solvateACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2009Azizolla Beheshti The title complex, (C24H20P)2[WZnS4(S6)]·C3H6O or (Ph4P)2[WS2(,-S)2{Zn(S6)}]·Me2CO, was unexpectedly obtained on attempted recrystallization of a mixed tungten,zinc complex of a tris(pyrazolato)borate ligand. The two metal centres of the anion have distorted tetrahedral coordination and the two tetrahedra share one S...S edge; tungsten is additionally coordinated by two terminal sulfide ligands and zinc by a chelating S62, ligand, which has one central S,S bond significantly longer than the other four, a pattern found to be consistent for this ligand. This is the first reported example of a tetrahedral zinc centre bridging an edge of a single tetrathiotungstate(VI) or tetrathiomolybdate(VI) anion, although there are many previous examples with other metals. [source] Bis[4-(trimethylammonio)phenyl] disulfide diiodide acetone solvateACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2009Zheng Zhang The title compound, C18H26N2S22+·2I,·2C3H6O, is an intermediate in the design of the zwitterionic thiolate 4-(trimethylammonio)benzenethiolate (Tab), in which a pair of aryl-substituted S atoms are linked by a covalent bond. The central S,S bond length is 2.020,(3),Å and the Car,S,S,Car torsion angle is ,84.1,(2)°. The crystal structure is stabilized by nonclassical hydrogen bonds which occur as intramolecular C,H...I interactions and intermolecular C,H...S and C,H...O contacts. In the crystal structure, both the dication and the two symmetrically independent iodide counter-anions are located on twofold crystallographic axes, whereas the acetone solvent molecule occupies a general position. [source] | ||||||||||