Calculation of Enthalpies of Formation of Secondary and Tertiary Aliphatic Carbenium Ions by Molecular Mechanics

Authors

  • Paul Müller Department of Organic Chemistry University of Geneva 30, quai Ernest-Ansermet, CH-1211 Geneve 4
  • Jacky Blanc Department of Organic Chemistry University of Geneva 30, quai Ernest-Ansermet, CH-1211 Geneve 4
  • Jiri Mareda Department of Organic Chemistry University of Geneva 30, quai Ernest-Ansermet, CH-1211 Geneve 4

DOI:

https://doi.org/10.2533/chimia.1985.234

Abstract

Steric energies (Est) of carbenium ions, calculated by MM2, may be converted into enthalpies of formation (ΔHf) by means of group increments. Increments of 204.7 kcal/mol for secondary and 187.4 kcal/mol for tertiary aliphatic carbenium ions, based on experimental ΔHf values of 2-propyl (191.8 kcal/mol) and tert-butyl cation (166.2 kcal/mol) are proposed. The calculated ΔHf values of eleven cations corrected for inductive effects due to β-alkyl substituents agree with experimental data.

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Published

1985-08-31

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