Syntheses and Solid-State Characterizations of <i>N</i>-Alkylated Glycine Derivatives

Abstract

Seven N-alkylated glycine derivatives were prepared and characterized using single-crystal X-ray diffraction, infrared spectroscopy and thermal analysis. Chloride salts, H2EtGlyCl, H2(n-PrGly)Cl and H2(i-PrGly)Cl were prepared by aminolysis of chloroacetic acid with respective alkylamine. Nitrate salts, H2EtGlyNO3, H2(i-PrGly)NO3, H2(n-PrGly)NO3 and zwitterionic compound H(n-PrGly)·1/3H2O were prepared using ion exchange reactions from corresponding chloride salts. In all the N-alkylated glycine chloride salts, two N-alkylglycinium cations and two chloride anions were connected into centrosymmetric dimers that were additionally hydrogen bonded into endless chains. In the nitrate salts, 2D networks of different topologies were formed through hydrogen bonds between nitrate anions and N-alkylglycinium cations. In compound H(n-PrGly)·1/3H2O, the zwitterionic N-(n-propyl)glycines and water molecules of crystallization were connected into the 3D hydrogen bond networks. Chloride salts have significantly more H⋯H and O⋯C contacts than nitrate salts. All chloride salts decompose in endothermic, while nitrate salts decompose in exothermic thermal events.

Keywords

• crystal structure
• <i>N</i>-alkylated glycine derivatives
• Hirshfeld surface analysis
• hydrogen bonding