Enthalpy of phase transitions of lactams

The transpiration method is used to measure the temperature dependences of the vapors pressures of azacyclobutan-2-one (I, CAS 930-21-2) azacyclohexan-2-one (II, CAS 675-20-7); azacyclooctan-2-one (III, CAS 673-66-5); azacyclononan-2-one (IV, CAS 935-30-8) and azacyclotridecan-2-one (V, CAS 947-04-6). Enthalpies of sublimation and vaporisation are determined. The temperatures and enthalpies of fusion of compounds (I, III-V) are found by means of differential scanning calorimetry. The dependences of the enthalpies of vaporisation of lactones, lactams, cycloalkanes, cycloalkanones on the size of a cycle are analyzed.