Nucleation Control and Separation of Ethyl Maltol Polymorphs II and III from Water‐Ethanol Solvent Mixtures

Abstract Nucleation control and separation of ethyl maltol polymorphs Form‐II and Form‐III from mixed water (W) and ethanol (E) solutions with nine different mixing ratios, ranging from 90W:10E to 10W:90E, is reported for the first time using conventional slow evaporation crystallization method. Solutions with compositions of 90W:10E to 60W:40E induced Form‐II, while the remaining five compositions resulted in the nucleation of Form‐III. Solubility, refractive index, and pH are determined for these solutions. Form‐II nucleated with prismatic‐like morphology whereas Form‐III exhibited platy‐like morphology, as observed through in situ optical microscopy. Structural confirmation, thermal behavior, and possible polymorphic phase transformation are analyzed using powder X‐ray diffraction and differential scanning calorimetry.