Comparison of Crystal Structures of New Racemic Chiral Compounds Showing and Not Showing the Phenomenon of Preferential Enrichment

Abstract

The crystal structures of (±)-[2-[4-(3-ethoxy-2-hydroxypropoxy)phenylcarbamoyl]ethyl] trimethylammonium p-chlorobenzenesulfonate [(±)-NCMe₃] and its terminal methoxy derivative, (±)-NCMe₃-OMe, are compared. The former racemate exhibited the phenomenon of Preferential Enrichment, whereas the latter failed to do so. Crystal data, (±)-NCMe₃: CuKα radiation, space group P 1, Z = 2, a = 9.848(5), b = 14.823(3), c = 9.147(1) Å, α = 97.81(1), β = 92.68(3), γ = 105.92(2)°, D _calc = 1.355 g/cm³, R = 0.056 for 3213 observed reflections; (±)-NCMe₃-OMe: CuKα radiation, space group P 1, Z = 2, a = 11.350(1), b = 14.568(2), c = 8.2981(4) Å, α = 94.346(7), β = 112.376(5), γ = 78.622(9)°, D _calc = 1.343 g/cm³, R = 0.069 for 1519 observed reflections.

Key Words:

• Preferential Enrichment
• Enantiomeric resolution
• Mixed crystal
• Racemic compound
• X-ray crystallography