LAUSR

In the cocrystallization process, real-time monitoring is effective for obtaining cocrystal products with a consistent quality. Low-frequency Raman spectra reflect the lattice vibration derived from crystalline differences; therefore, Raman spectroscopy is expected to be useful for monitoring pharmaceutical cocrystals, which are difficult to distinguish by Raman spectroscopy in the fingerprint region. We attempted to monitor the formation of cocrystals with 1:1 and 2:1 cocrystals consisting of carbamazepine and 4-aminobenzoic acid using probe-type low-frequency Raman spectroscopy. Real-time measurements were performed while stirring a composition known to form 1:1 and 2:1 cocrystals via reaction crystallization methods, and the spectra derived from the cocrystals were confirmed after 5 min. To monitor the transition of cocrystals toward a stoichiometry of 2:1 from 1:1 and toward 1:1 from 2:1, specified amounts of raw materials were added to the cocrystals suspended in ethanol. The cocrystals with a differ...