Polymorphic Control of α and βdl‐Methionine through Swift Cooling Crystallization Process

Abstract

Polymorphic control and crystal nucleation of and polymorphs of dl-methionine, an essential amino-acid, is attained from saturated aqueous solution through swift cooling crystallization process by generating wide range of supersaturation (0.02 < < 2.19) in the temperature range of 323-274 K. The type of nucleation is very much supersaturation dependent: while lower supersaturation range (0.02 < < 0.08) prefers the stable form, higher supersaturation range (1.20 < < 2.19) yields metastable form. In situ optical microscopy and X-ray diffraction analyses confirm the morphological and structural distinction of the grown polymorphs.

Oiling‐Out in Industrial Crystallization of Organic Small Molecules: Mechanisms, Characterization, Regulation, and Applications

“…For cooling crystallization, the cooling rate also has an effect on oiling-out. [85] For crystallization processes with oiling-out, the change in cooling rate will lead to different super solubility curves and turbidity lines. To avoid the occurrence of oiling-out, it is necessary to minimize the cooling rate during the crystallization process.…”