“…In the case of the series of 1,3-dimethyl-5-alkyluracils (6,17,19,20) [5,6,19], 1,6-dimethyl-3-alkyluracils (7,(24)(25)(26) [8,11] and 1,3-dimethyl-6-alkyluracils (10,21-23) [5,11] erratic changes were observed to occur in the values of the enthalpy of hydration. The higher values of the enthalpy increment correspond to the odd number of CH 3 groups added while the lower values correspond to those with the even n CH 2 number.…”