APPARENT MOLAR HEAT-CAPACITIES AND VOLUMES OF SOME ALKYLATED DERIVATIVES OF URACIL AND ADENINE IN AQUEOUS-SOLUTION AT 25-DEGREES-C

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-degrees-C. It was found that the partial molar volumes and heat capacities correlate linearly with the number of substituted methylene groups -CH2- 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, V2o and C(p2)o, depending on the substitution of alkyl and cyclooligomethylene groups.