Analysis and Comparison of Commonly Used Acidic Resolving Agents in Diastereomeric Salt Resolution – Examples for dl-Serine

Multiplicity of Equilibrium States in Separating Stereoisomeric Mixtures of Nafronyl Oxalate by Crystallization

“…Different types of solid phase behavior of chiral systems can be distinguished, that is, mixture components can form (a) simple eutectics, when they are completely immiscible in the solid phase, which provides mixtures of the individual crystals, (b) intermediate compounds, in which both components form a well-defined arrangements in the solid phase, or (c) solid solutions (designated also as mixed crystals or isomorphic mixtures), which occur in cases of complete miscibility in the solid phase. − The formation of solid solution usually results from the substitution of isomorphous species, which have very similar unit-cell dimensions . Continuous solid solutions in chiral organic systems are rare, however, partial solid solutions with limited miscibility in the solid phase occur quite often. − Typical phase diagrams, illustrating SLE of various diastereomeric systems, are presented in Figure .…”

Resolution via Diastereomeric Salt Crystallization of Ibuprofen Lysine: Ternary Phase Diagram Studies

“…The composition at which both diastereomeric salts have the highest solubility is termed as the eutectic composition . Theoretically, the salt formation results in three crucial types of phase diagrams: simple eutectic, i.e., exhibits only one eutectic; double salts, i.e., exhibits two or more eutectics at varying composition of the two salts in the chosen solvent; and mixed crystals which means that no eutectics are present and, as a result, the molecules are randomly arranged in the crystal unit cell .…”

“…Thermodynamic data, i.e., binary phase diagrams (BPDs) and ternary phase diagrams (TPDs) of the two diastereomeric salts in the solvent system at different temperatures, and kinetic properties, i.e., metastable zone widths in an appropriate solvent are required to design an appropriate crystallization process . In this study, the solid mixtures of the p ‐/ n‐salts were prepared with an analytical balance (VWR; resolution 0.01 mg).…”

Solid solutions of quasi-isomorphous diastereomeric salts – kinetics versus thermodynamics

“…Each year successful and unsuccessful racemic resolutions, detailed examination of the structural relationships between diastereomeric salts, the energy differences of diastereomeric salts, empirical correlations, as well as computer assisted modeling are reported. [11][12][13][14][15][16][17][18] Nevertheless, a resolution technique is still selected by trial and error. In a successful Pasteur resolution, two diastereomeric salts precipitate separately, according to their solubility.…”

“…It is intriguing that although recrystallization from a solution is a widely used purification method for the crystalline organic compounds, cocrystallization of two diastereomeric salts and formation of solid solutions in attempts of Pasteur resolution is common. 14,19,20 It was shown that cocrystallization of two diastereomeric salts from a solution containing even a large excess of one diastereomeric salt results from an extra hydrogen bond formed by the other ''deficient'' diastereomeric salt. 21,22 Kitaigorodsky pointed out that similarity of molecular structures plays a crucial role in formation of organic solid solutions.…”