Apparent molar heat capacities and volumes of some alkylated derivatives of uracil and adenine in aqueous solution at 25�C

Abstract

Densities and apparent molar heat capacities of some alkylated derivatives of uracil and adenine: 1-methyluracil, 1,3-dimethyluracil, 1,3-diethylthymine, 5,6-trimethylene-1,3-dimethyluracil, 5,6-tetramethylene-1,3-dimethyluracil, 5,6-pentamethylene-1,3-dimethyluracil, 2,9-dimethyladenine, 2-ethyl-9-methyladenine, 2-propyl-9-methyladenine, 8-ethyl-9-methyladenine, 6,8,9-trimethyladenine and 8-ethyl-6,9-dimethyladenine were determined using flow calorimetry and flow densimetry at 25°C. It was found that the partial molar volumes and heat capacities correlate linearly with the number of substituted methylene groups-CH 2 -as well as to the number of hydrogen atoms, n H , belonging to the skeleton of the molecule. In the case of alkylated uracils a difference was observed in the values at infinite dilution V 2 o and C p2 o , depending on the substitution of alkyl and cyclooligomethylene groups.