APPARENT MOLAR VOLUMES AND HEAT-CAPACITIES OF SOME ALKYLATED DERIVATIVES OF ADENINE IN AQUEOUS-SOLUTIONS

There were determined experimentally densities of aqueous solutions of some alkylated derivatives of adenine: 6,8,9-trimethyladenine [m3(6,8 ,9,)Ade], 6,9-dimethyl-8-ethyl-adenine [e8m2(6,9)Ade], 6,9-dimethyl-8- propyladenine [p8m2(6,9)Ade], 6,9-dimethyl-8-butyl-adenine [b8m2(6,9)A de], 8,9-dimethyladenine [m2(8,9)Ade], 9-methyl-8-ethyladenine [e8m9Ad e], 2-ethyl-9-methyladenine [e2m9Ade], 2-propyl-9-methyladenine [p2m9A de], 2-butyl-9-methyladenine [b m9Ade] and heat capacities per volume unit of m2(8,9)Ade and p8m2(6,9)Ade at 25-degrees-C. Partial molar vol umes, Van der Waals volumes for the studied compounds were calculated. There were found linear dependences of partial molar volumes V2(0) on the number of substituted methylene - CH2 - groups as well as on the Van der Waals volumes. Similar dependences of partial molar heat capac ities C(p2)0 on n(CH2) groups in series of 9-methyl-2-alkyladenines an d 6,9-methyl-8-alkyladenines are not coincident with the value of 90 k Jmol-1 generally found. In addition, the variation of apparent molar h eat capacities C(p)PHI with the temperature and the concentration are presented.