Automatic estimation of heats of atomization and heats of reaction

Various additivity schemes for estimating heats of atomization have been evaluated to test their usefulness for designing a computer program. The approach is based on the Allen scheme and uses parameters obtained from thermochemical data. In addition, a method has been developed which allows the direct calculation of reaction enthalpies. Only the immediate environment of the bonds involved in the reaction has to be scanned. A program based on this method utilizes thermochemical parameters, too. Computation times with this program are extremely short and independent of the size of the molecules participating in the reaction. The procedure can be applied to a large variety of organic compounds. Examples demonstrate the accuracy of the predicted values.