The enthalpies of formation (AH() for 24 hydrocarbon radicals (R"), mainly polycyclic aromatic radicals with the complex structure, were determined from the published data on bond dissociation energies. The ,..k//f ~ values of the corresponding molecules were calculated, in the majority of cases, by the macroincrement method. Calculations by the group contribution method were performed. Some AHf*(R') values were compared to those calculated by the additive-group method. Calculations were performed, and the conjugation energies of the radicals were discussed. The errors of determination of the A//f*(R" ) values found were estimated. Due to this work, the database for AHf ~ values of hydrocarbon radicals was increased more than by 25%.

The enthalpies of formation (AHf) for 23 halosubstituted radicals were determined from the published data on bond dissociation energies. The A/'/f values of the corresponding molecules necessary for the calculation of AHf ~ of the radicals were taken from handbooks or calculated by the additive-group method. The conjugation energies of the radicals are calculated, and the effect of substituents at the ~-system on these values was shown. Errors of determination of the AHf values of the radicals were estimated.

No abstract

No abstract

Durch Umesterungen von Orthoameisensäuretriäthylester mit den Alkylhemithioformalen (I) bei 130°C lassen sich die Alkylmercaptomethylorthoester (II) darstellen.