Journal of Chemical and Engineering Data, Vol.52, No.1, 93-97, 2007
Heat capacities of uracil, thymine, and its alkylated, cyclooligomethylenated, and halogenated derivatives by differential calorimetry
The molar heat capacity (C-p) of solid uracil, its alkylated and halogenated derivatives, and cyclooligomethylenouracils in the temperature range of (298.15 to 343.15) K by a differential scanning calorimeter (SETARAM TG-DSC 111) were determined. It was demonstrated that the C-p value increases by increasing the number of methylene groups attached to the diketopyrimidine ring. The correlations C-p = f(T) are given. The contributions of C-CH3, N-CH3, and C-NO2 groups as well as F, Cl, Br, and I atoms in the value of C-p for the temperature of 298.15 K are presented. The Chickos method for calculation of C-p values is discussed.