Detection of the II–I Etiracetam solvent-mediated polymorphic transformation through the online monitoring of the suspension apparent viscosity

Polymorphism in hexanitrohexaazaisowurtzitane crystallized from solution

“…The crystallization behavior of form a would be discussed in the following section. Moreover, the crystallization of form e may not be simply related to the solvent effect, but rather to supersaturation and composition of the crystallization system and so on [39][40][41][42][43].…”

Ternary and quaternary phase diagrams: key tools for chiral resolution through solution cocrystallization

“…All vials were hermetically sealed and heated up to 60 uC until complete dissolution. They were stored at constant temperature and seeded with all of the solid forms possibly occurring in the corresponding ternary phase diagram (for each diagram the appropriate selection was made from RS-1 form I, [34][35][36][37] S-1, S-2, and S-1:S-2 cocrystal). After two weeks, the system was assumed to have reached equilibrium.…”

The importance of screening solid-state phases of a racemic modification of a chiral drug: thermodynamic and structural characterization of solid-state phases of etiracetam

“…As described elsewhere Herman, Haut, Douieb et al, 2012;Herman, Leyssens, Debaste & Haut, 2012;, FI and FII are true polymorphs which are enantiotropically related. FI is the most stable form below 303.5 K, whereas FII is the most stable form above this temperature.…”

“…Single FII crystals (stable above 303.5 K) can be obtained leaving single crystals of FI in suspension in MeOH at 313 K for 48 h. A solvent-mediated polymorphic transformation occurs, with dissolution of FI, combined with nucleation and crystal growth of FII crystals. The solvent mediated transition is described elsewhere for the etiracetam compound Herman, Haut, Douieb et al, 2012;Herman, Leyssens, Debaste & Haut, 2012;.…”

“…The racemic modification of 2-(2-oxo-pyrrolidin-1-yl)butyramide, also called etiracetam, presents itself as a racemic compound Herman, Haut, Douieb et al, 2012;Herman, Leyssens, Debaste & Haut, 2012;, 1 and can be encountered as a racemic intermediate during the synthesis of leviteracetam. Up to now, two distinct polymorphic forms of etiracetam, called form I (FI) and form II (FII), were identified and intensively studied elsewhere Herman, Haut, Douieb et al, 2012;Herman, Haut, Aerts & Leyssens, 2012;Herman, Leyssens, Debaste & Haut, 2012;. However, no structural characterization of these polymorphs was given.…”