Ab initio molecular orbital calculations on the conformations of some unsaturated fragments of lipid molecules: 1-Butene, cis-2-pentene and 1,4-pentadiene

Conformational energies have been calculated for the title compounds which are basic fragments of physiologically active polyunsaturated fatty acids. For 1-butene extremely good accordance has been obtained with experimental data. In cis-2-pentene a strong influence of the cis methyl group on the potential energies for internal rotation has been found. For 1,4-pentadiene no great influence has been found from a possible coupling of the two rotors on the relative stabilities of the two stable conformations. Reasonable agreement has been observed with similar calculations published recently.