The interaction between some ethyl esters of aminoacids and acetic acid in carbon tetrachloride

The dimerization constant, K₁ of acetic acid in CCl₄ is determined by an IR spectrometric method and is found to have a value of 2252M⁻¹ at 20°. The association constants, K₂, for the interaction between the acetic acid monomer and some aminoacid ethyl esters are determined by the same method and found to have the values given (in M⁻¹ at 20°) for the esters of the following aminoacids: glycine (282 ± 24), dl-alanine (236 ± 33), dl-α-aminobutyric acid (139 ± 11), α-aminoisobutyric acid (172 ± 18). dl-norvaline (104 ± 13), dl-valine (150 ± 8), dl-leucine (108 ± 18) and 3-phenyl-dl-alanine (140 ± 21). A correlation of these experimental values with some structural parameters related to the steric effect of the substituents on the esters is proposed.