13C-NMR spectra of positional isomers of long-chain conjugated diacetylenic fatty esters

摘要: Abstract The 13C-NMR spectra of a set 14 positional isomers conjugated diacetylenic fatty esters were studied. Full interpretation the spectroscopic results was only possible after sub-sets symmetrical dialkyl and dialkanoate substituted diacetylenes prepared effects ω-methyl carbomethoxy group on chemical shifts acetylenic carbon nuclei assessed. shift outer inner atoms methyl alkadiynoates appeared at about 75–79 65–66 ppm, respectively. Strong shielding α-effects system immediately adjacent observed. In general, carboxylic ester caused strong effect systems, but deshielding nuclei. position in alkyl chain could be determined for isomers, where number methylene groups between less than 7; 4. Twelve identified by this technique.