Synthesis and mass spectra of esters of branched chain fatty acids

摘要: Abstract The Wittig reaction between alkylidene triphenylphosphoranes [ R — CH = P(C 6 H 5 ) 3 , where varied from to n C 17 35 ] and methyl 12-oxooctadecanoate or 10-oxohexadecanoate in dimethylformamide (DMF) has been employed the synthesis of a partial homologous series esters branched chain fatty acids high yields. effect various ratios reactants both DMF dimethylsulfoxide (DMSO) was investigated. Purification triphenylphosphine oxide readily accomplished by chromatography on column silicic acid-Celite impregnated with silver nitrate. mass spectral fragmentation patterns these compounds were studied. More like spectra α, β-unsaturated esters, contrast normal unsaturated pattern allowed location double bond at branch point. A fragment ion [C 2 + resulting two proposed allylic cleavages McLafferty transfers γ-hydrogen atoms present 51–100% relative abundance unambiguous determinations length alkenyl branch. trimethylsilyloxy (di-OTMS) derivatives compounds, however, di-OTMS did not allow determination position. PNMR are described.