Acta Chimica Slovaca (ACS) publishes papers on fundamental and applied aspects of chemistry, biochemistry, chemical technology, chemical engineering and process control, biotechnology and food technology. Welcome are also topics which include chemical aspects of materials, physical chemistry and chemical physics, analytical chemistry, macromolecular chemistry and biomedical engineering.

Quantum-chemical study of C—H bond dissociation enthalpies of various small non-aromatic organic molecules

Peter Poliak, Adam Vagánek *

Institute of Physical Chemistry and Chemical Physics, Slovak University of Technology, Radlinského 9, SK-812 37 Bratislava, Slovakia

E-mail: * adam.vaganek@stuba.sk

Abstract: In this work, C—H bond dissociation enthalpies (BDE) and vertical ionization potentials (IP) for various hydrocarbons and ketones were calculated using four density functional approaches. Calculated BDEs and IPs were correlated with experimental data. The linearity of the corresponding dependences can be considered very good. Comparing two used functionals, B3LYP C—H BDE values are closer to experimental results than PBE0 values for both used basis sets. The 6-31G* basis set employed with both functionals, gives the C—H BDEs closer to the experimental values than the 6-311++G** basis set. Using the obtained linear dependences BDEexp = f (BDEcalc), the experimental values of C—H BDEs for some structurally related compounds can be estimated solely from calculations. As a descriptor of the C—H BDE, the IPs and 13C NMR chemical shifts have been investigated using data obtained from the B3LYP/6-31G* calculations. There is a slight indication of linear correlation between IPs and C—H BDEs in the sets of simple alkanes and alkenes/cycloalkenes. However, for cycloalkanes and aliphatic carbonyl compounds, no linear correlation was found. In the case of the 13C NMR chemical shifts, the correlation with C—H BDEs can be found for the sets of alkanes and cycloalkanes, but for the other studied molecules, no trends were detected.

Keywords: BDE, NMR chemical shift, alkanes, alkenes, descriptor, radical scavenging

Full paper in Portable Document Format: acs_0147.pdf

Acta Chimica Slovaca, Vol. 6, No. 1, 2013, pp. 64—72, DOI: 10.2478/acs-2013-0012