The dependences of the thermodynamic properties of cyclic urethans on their composition and structure

The calorimetric data on dimethylenecyclourethan, trimethylenecyclourethan, 2-methyltrimethyl-enecyclourethan, 2,2-dimethyltrimethylenecyclourethan, a nd tetramethylenecyclourethan in the temperature range 5-340 K were used to determine the dependences of heat capacity C(p)degrees (T), entropy S degr ees (T), enthalpy H degrees (T) - degrees (0), Gibbs function G degrees (T) - H degrees (0), standard enthalpy of combustion Delta H-c degrees and the thermodynamic parameters of formation (Delta H-f degrees, Delta S-f degree s, and Delta (f)G degrees) of cyclourethans on the number of ring carbon at oms at various temperatures in the range 50-300 K. The dependences at given temperatures were straight lines, which could be used to estimate the same thermodynamic properties of still unstudied cyclourethans. The thermodynam ic properties of cyclourethans with 7-13 carbon atoms were estimated in the specified temperature range with errors not exceeding 3%.