Structural Studies of Racemates and Quasiracemates: Chloro, Bromo, and Methyl Adducts of 2-Phenoxypropionic Acid

Abstract

Quasiracemic compounds derived from the enantiopure Cl, Br, and CH3 analogues of 2-phenoxypropanoic acid crystallize to give approximate centrosymmetry supramolecular assemblies. Each quasiracemate forms the anticipated heterodimers via O−H···O carboxyl interactions that lead to two distinct packing motifs in space group P21 with Z′ = 2 (Cl/Br and Br/CH3) or 8 (Cl/CH3 and Br/CH3). The Z = 2 quasiracemates are isostructural with (rac)-Cl and (rac)-Br, while the Z′ = 8 structures form molecular patterns that resemble the packing preferences of (rac)-CH3. The Br/CH3 quasiracemate was retrieved as concomitant polymorphs.