APPARENT MOLAR VOLUMES, HEAT-CAPACITIES, AND MOLECULAR EXCLUDED VOLUMES OF METHYLATED, HYDROXY AND METHOXY DERIVATIVES OF 1-METHYL-CYTOSINEIN AQUEOUS-SOLUTIONS AT 25-DEGREES-C

Densities and specific heat capacities of aqueous solutions: I-methylc ytosine; 1-methyl-N-4-hydroxycytosine; 1,5-dimethylcytosine; 1,N-4-dim ethylcytosine; 1,5-dimethyl-N-4-hydroxycytosine; 1-methyl-N-4-methoxyc ytosine; 1,N-4,N-4-trimethylcytosine, 1,5-dimethyl-N-4-mmethoxycytosin e were determined using flow calorimetry and flow densimetry at 25 deg rees C. Apparent molar volumes and heat capacities were then determine d. Molecular excluded volumes were evaluated A relationship was found between the values of the increments in partial molar values and the k ind of groups substituted Four types of contributions were distinguish ed: substitution of hydrogen on C, N, and O (in OH group on N4) atoms by CH3 group and replacement of hydrogen on N4 atom by OH group. The c orrelation between the experimental partial molar volumes and calculat ed molecular excluded volumes was also elaborated.