A facile synthesis and IR-LD spectral elucidation of N-acetyl amino acid derivatives

The synthesis of N-acetyl derivatives of α-amino acids (L–Gly, L–Val, L–Phe, L–Ile, L–Pro and L–Cys) using a simple and efficient method for preparation was carried out. The N-acetyl derivatives were obtained using acetic anhydride in basic conditions at room temperature. The methyl amides of N–acetyl amino acid were synthesized by mixed anhydride procedure using a Piv–Cl as a reagent. The conventional and IR–LD spectral analysis were applied for elucidation and characterization of typical IR-bands of the starting and intermediate compounds. Spectral investigation includes IR-characteristic bands assignment and elucidation of amino acids as zwitterions structures – L-Valine (L– Val), L–Proline (L–Pro) L–Cystein (L–Cys) and their intermediates by linear-dichroic infrared (IR–LD) spectroscopy of oriented solid sample as a nematic liquid crystal suspension. The experimental IR-characteristic bands obtained, were accompanied with spectral elucidation and structural prediction of the investigated compounds.