The mechanism of thermal dimerization of methyl 9-cis, 11-trans-octadecadienoate was studied by a kinetic method. The study shows that the dimerization proceeds in two distinct stages : the conver-sion of the cis, trans-conjugated dienoate to its trans, trans-conjugated isomer (first stage) and the dimerization of the trans, trans-conjugated isomer, or combination of the cis, trans-conjugated and trans, trans-conjugated isomers, by the mechanism of Diels-Alder addition reaction (second stage). In the dimerization of the trans, trans-conjugated dienoate, one of the two molecules of trans, trans-conjugated dienoate acts as diene and the other as dienophile. On the other hand, in the addition, reaction between the cis, trans-conjugated and trans, trans-conjugated isomers, the cis, trans-conjugated dienoate acts as dienophile but not as diene. From the results of the determination of rates of first and second processes at 270 and 290°C, it has been found that trans, trans-conjugated octadecadienoate has twice or three times as great a dienophilic activity as cis, trans-conjugated octadecadienoate.
The synthesis of sulfides by the dehydration of various alcohols with n-octanethiol (1) has been investigated. The reactions proceed in the presence of acid catalysts, and the use of Lewis acids as catalysts was usually more effective in the yield of sulfides than protonic acids. The reactivity of butanols was in the order of tertiary > secondary > primary alcohol, but the reaction of (1) with primary alcohol was scarce. The effect of Lewis acids for the reaction of benzylalcohol (2) with (1) was in the order ZnCl2 > SbCl3 > SnCl4 > FeCl3 > AlCl3. The rates of formation of the sulfide and activation energy were measured for the reaction of (2) with (1). The reaction was of the first-order with respect to the concentration of (2) but it was independent of (1). The apparent activation energy was about 26.3 kcal/mol. From the above results, it seems that the formation of carbonium ion takes a rate-determing step in the reaction of (2) with (1).
Antioxidant ability of alkylen-bis-phenol derivatives was investigated. The methyl ester of fatty acids used for the test was prepared by alkali-catalyzed methanolysis of soybeen oil, followed by distillation in vacuum under nitrogen stream. The derivatives were added to the methyl ester at 0.01% level, and were measured by active oxygen method (AOM) and electron donnor effect. ρ-Dimethoxy derivatives (I, V, VI) did not show any effect. Hydroxy derivatives (II, III, IV, VII) improved the oxidative stability of the methyl ester, but the effect of derivatives containing carbonyl in the chain (II, III, IV) was less than half of the effect of the sample without containing carbonyl group (VII), 1, 16-bis (2, 5-dihydroxyphenyl) hexadecane (BDPH). The difference observed in the antioxidant ability may probably due to a result of hydrogen-bonding between hydroxyl and carbonyl radical, which reduces hydrogen or electron donative ability from the molecule. The antioxidant ability of BDPH was also compared with the commonly used antioxidant for vegetable oils, such as nordihyroguaiaretic acid (NDGA), α-tocopherol (α-Toc), propyl gallate (PG), ethyl protocatecuate (EP), buthylated hydroxyanisole (BHA) and dibutyl hydroxytoluen (BHT). BDPH was more effective than these antioxidants. The effect of BDPH increased proportionally with the concentration within 0.005 to 0.1%. Additivity in the antioxidant ability of BDPH with other typical antioxidants was observed at 0.01% levels. The systems of BDPH plus BHT, and BDPH plus α-Toc showed super-additivities, while BDPH plus NDGA was less effective than EDPH plus BHA. From these observations BDPH might be a usefull antioxidant practically.
The rates of coalescence of oill drops at oil-water interface were measured, while interfacial tension and rate constant data were obtained for some of the systems. In all systems, the effects of nonionic surfactants added to the oil or water phase were investigated. It was found that no relationship exists between the rate of coalecsence and its interfacial tension. Oil drops are greatly stable in general when the amount of stabilizing agents dissolved in oil are above the saturation. These phenomena may relate the interfacial viscosity. In the every first maxima of the used surfactant series, that of OP is the largest, and therefore, OP seems to make the stron-gest complex with ST. The stabily of oil drops differs from so called emulsion stability, but there considered a correlation between the coalescent rate of oil drops and the emulsion stability, from the facts that these stabilities increase by the increased visosities of thier systems or by making electrical double layers on thier drops.
Surface active properities of the aqueous solutions of nonionic surfactant containing metal soaps in solubilized form were investigated. Polyoxyethylene cetyl ether (18 mole adduct C16-18) was synthesized as nonionics used, while metal soaps used were the same as in the previous reports, i.e., laurates and ricinoleates of alkali and alkaline earth metals. In binary aqueous solutions, the nonionic surfactant to the metal soap was five to one in molar ratio, and the concentrations of the nonionics were mainly 0.02 and 0.001 mol/l. Synergistic effects were observed to some extent on the surface tention, wetting power for felt and cotton, and foam stability of the mixed solutions. In the case of foaming power there were no synergistic effects, which is due to the superiority of C16-18 itself, while in contact angle, ricinoleates-containing solutions were slightly inferior than that of the single solution of C16-18. Among the metal salts constituting binary systems, alkaline earth metal salts were superior in all properties than alkali metal salts, and laurates were superior than ricinoleates in the properties except wetting and foaming powers. The electric conductivity of binary solutions was considirably high and the specific conductance of the alkaline earth metal salts was about twice as much as that of the alkali metal salt solutions. In respect to the synergistic effect, the C16-18-metal soap solutions were considerably inferior than dodecyl pyridinium chloride-metal soap solutions.
The characteristics of seed oils from Tamarind, Persimmon, Himebishi, Himeyashabushi and Lotus were investigated. Each oil was obtained by extraction of the dried seeds with ether, followed by treating with n-hexane. The characteristics of seed oils (Table-1) and fatty acid compositions by GLC (Table-2) were investigated. In order to examine the glyceride compositions in seed oils, the purified triglycerides obtained by TLC were hydrolized in to β-monoglyceride by the action of pancreatic lipase. The β-monoglyceride separated by TLC was esterified into methyl ester with 0.2 N-sodium methoxide solu. to examine the composition of fatty acids in 2-position of triglyceride by GLC (Table-3). Triglyceride compositions in seed oils were also calculated (Table-4).