Synthesis and physical properties of some 2,3- and 2,2′-epithio C18 fatty acid derivatives

Synthesis, characterization, and evaluation of 10-undecenoic acid-based epithio derivatives as multifunctional additives

Novel epithio compounds from alkyl epoxy undecanoates (n-alkyl, C1, C4, and C6; isoalkyl, C3, C4, and C8) were synthesized using an ammonium thiocyanate in ionic liquid 1-methylimidazolium tetrafluoroborate/H2O (2:1) solvent system in 85-90% yields by gas chromatographic (GC) analysis. The synthesized products were characterized by (1)H and (13)C nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy (FTIR), gas chromatography, and GC mass spectral (GC-MS) analyses and evaluated for their antioxidant, extreme pressure (EP), and antiwear (AW) properties in three different base oils, namely, epoxy jatropha fatty acid n-butyl esters (EJB), di-2-ethylhexyl sebacate (DOS), and mineral oil (S-105). Among the synthesized products, n-butyl epithio undecanoate exhibited superior antioxidant property (229.2 °C) compared to butylated hydroxytoluene (BHT, 193.8 °C) in base oil DOS and comparable performance in EJB and S-105 base oils. All of the epithio derivatives exhibited significantly enhanced weld point for the base oils EJB and DOS at 2 wt % level and displayed moderate enhancement in S-105 base oil. Methyl epithio undecanoate at 0.6% concentration exhibited considerable improvement in the wear scar of DOS base oil. The synthesized epithio derivatives have potential as multifunctional additives in lubricant formulations.

Gas-liquid chromatographic properties of positional isomers of methyl thia, selena, and tellura laurate analogs

Gas-liquid chromatographic analyses of three complete series of synthetic positional isomers of methyl thia, selena, and tellura laurate analogs were carried on a nonpolar (SE-30) and a polar (SP-2330) stationary phase. The average ECL (equivalent chain length) values of the thia, selena, and tellura laurate on SE-30 stationary phase were 13.8, 14.8, and 15.7, respectively, while on SP-2330 the average values for the same series were 17.1, 19.0, and 19.1, respectively. Positional isomers with the heteroatom at the 2-position exhibited the lowest ECL values, while those with the heteroatom at the omega-1 position gave the highest ECL values and were readily separated from the other positional isomers of the same series of analogs by this technique.

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)