Enthalpies of transfer of amino acids from water to aqueous solutions of N-methylacetamide and N,N-dimethylacetamide at T=298.15 K

Enthalpies of solution of glycine, L-alanine and L-serine in aqueous solutions of N-methylacetamide and N,N-dimethylacetamide were measured at 298.15 K. Enthalpies of transfer (Delta H-tr) of amino acids from water to aqueous solutions of amides were derived. It has been show that the enthalpies of transfer of amino acids are positive and increase with the increasing concentration of amides. The relative order of Delta H-tr of amino acids in the same concentration of NMA or DMA is L-serine < glycine < L-alanine. The influence of side group Of L-alanine and L-serine on Delta H-tr has been discussed in terms of structural interaction. The results were compared with those in aqueous formamide, N-methylformamide and N,N-dimethylformamide solutions. (C) 2008 Elsevier B.V. All rights reserved.