The interaction of the oxidized fraction of arabinogalactan (OFAG) with acetylsalicylic acid (ASA) in aqueous solutions was studied using UV spectroscopy. It was shown that in the reaction system under study, complex compounds of the composition 1:1 are formed, when for each individual COOH group of OFAG there is one molecule of ASA. Using the method of molar ratios, the stability constants (K) of the resulting complexes were calculated in the temperature range 291–316 K. It was established: 1) at these temperatures, OFAG and ASA form fairly stable complexes (K ~ 103–104 L/mol); 2) with increasing temperature, the K values decrease. The study of the temperature dependences of K made it possible to determine the thermodynamic parameters of complex formation.
