The preparation and some physical properties of ten methyl dithiastearate isomers.
Ten methyl dithiastearate isomers, containing 0-4 methylene groups between the two sulfur atoms in each of the molecules, were synthesized using a one-pot synthesis approach. The preparation of the tetra-methylene (3,4), tri-methylene (5,6) and di-methylene (7,8) interrupted methyl dithiastearate isomers involved the asymmetric coupling of n-bromoalkanes, alkanedithiols and omega-bromoalkanoic acids. The mono-methylene interrupted isomers (9,10) were prepared from dibromethane, which was allowed to couple with n-alkanethiols and omega-mercaptoalkanoic acids. For the non-methylene interrupted isomers (11,12), n-alkanethiols were initially converted to the sulfenyl bromide and reacted with omega-mercaptoalkanoic acids. These sulfur-containing fatty ester analogues were found to be more polar and with longer retention times than methyl stearate when analyzed by TLC (silica) and GC (SE-30) respectively. In the 1H-NMR analysis the shifts of the protons of CH2 groups adjacent to the sulfur atoms in 3-6 appeared at 2.50-2.60 (t) delta, while the tri-methylene interrupted isomers (5,6) furnished an additional characteristic signal at 1.84 (quintet) delta arising from the protons of the beta-positioned CH2 between the sulfur atoms. Compounds 7-8 gave a singlet at 2.70 delta, while 9,10 also gave a singlet at 3.64-3.65 delta for the protons of the CH2 group situated between the sulfur atoms. In compounds 11,12 the shift of the protons of the CH2 adjacent to the sulfur atom appeared at 2.68 (t) delta.(ABSTRACT TRUNCATED AT 250 WORDS)
Jie
M S
MS
Department of Chemistry, University of Hong Kong.
Bakare
O
O
D002849:Chromatography, Gas; D002855:Chromatography, Thin Layer; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D013055:Spectrophotometry, Infrared; D013228:Stearates / Q000138:chemical synthesis*; D013229:Stearic Acids / Q000138:chemical synthesis*; D013440:Sulfides / Q000138:chemical synthesis
D013228:Stearates; D013229:Stearic Acids; D013440:Sulfides