The fatty acids of the seed oil of Lindera obtusiloba Blume isolated by distillation and column chro_natomatography were identified by gas chromatography, JR. Mass, NMR spectrometry and the chemical methods. The fatty acids identified were octanoic, decanoic, cis-4-decenoic, undecanoic, dodecenoic, cis-4-dodecenoic, tridecanoic, tetradecanoic, cis-4-tetradecenoic, pentadecanoic, hesadecanoic, hexadecenoic octadecanoic, oleic, linoleic and eicosenoic acid. The major component was cis-4-dodecenoic acid.
Thermal reaction of safflower oil fatty acids in the presence of magnesium iodide was studied under the following reaction conditions : concentration of magnesium ioeide 5, 2.5, and 1 wt%, temperature 200°C; concentration of magnesium iodide 5 wt%, temperature 180, 160, and 140°C. The conjugation and monoenoic acid formation reactions using fatty acids proceeded more remarkable than those in the case of safflower oil under the same reaction conditions. The maximum amounts of conjugated and monoenoic acids formed from fatty acids under above reaction conditions were 53 and 73%, respectively. When methyl ester of safflower oil fatty acids were heated in the presence of 5 wt% of magnesium iodide at 200°C, the conjugation reaction did not take place. In order to clarify the reason why conjugation reaction does not take place using methyl ester as a starting material, substances formed by heating methyl oleate as well as methyl esters of safflower oil fatty acids with magnesium iodide were examined. As a result of analyses of substances formed, it was found that methyl iodide and magnesium soap were formed. When methyl ester was heated with magnesium iodide, methyl iodide and magnesium soap were formed without the liberation of iodine from magnesium iodide. It is considered that the absence of liberated iodine in the reaction mixture results in none of conjugation reaction.
In a previous paper, authors assumed that glyceride monomers with some functional groups, which were eluted with 6O% isopropyl ether (IPE) in n-hexane on silicic acid chromatography, should be responsible for the taste of thermally oxidized soybean oil (TOSO). However, we detected later the presence of “heated oil-like” taste in IPE-ethyl ether (1 : 1) fraction rather than in 60% IPE fraction. In the present study, the separation of this polar fraction components by gel permeation chromatography was carried out. The fraction with mean molecular weight of 306, obtained by twice gel chromatography, did not have the “heated oil-like” taste after the passing through the Schwartz column. 2, 4-Decadienal and several 2-alkenals containing 4 to 10 carbon atoms were detected in the carbonyl compounds eluted from the Schwartz column. These results indicated that the glycerides in TOSO are all tasteless. However, carbonyl compounds such as 2, 4-decadienal and some other low molecular weight compounds were found to have “heated oil-like” taste.
Many studies have been carried out on the odour of volatile decomposition products (VDP) formed during the thermal oxidation of edible fats and oils. However, little is known on the taste of these compounds. This paper deals with the organoleptic tests of VDP. VDP used for the tests was obtained in 0.05% yield during the molecular distillation of thermally oxidized soybean oil in a previous experiments. VDP was fractionated into free fatty acids, lactones, sterols and alcohols, and carbonyl compounds. Besides 2, 4-decadienal and several 2-alkenals, which were detected as the flavor of heated oil as described in a previous paper, 2-nonenoic-γ-lactone and 1-pentene-3-ol were synthesized and used for the tests. The results indicated that lactones and carbonyl compounds were greatly responsible for the flavor of heated oil.
Hydrogen deuterium exchange reaction of 2-methylpyridine has been studied by using several fatty acids as catalysts. The reaction was carried out in a sealed pyrex tube at 120°C, and the contents of the products were determined by mass spectrometry. Reaction of 2--methylpyridine with monodeuteroacetic acid (1 : 1, mol/mol) arrived at a equibrium (d0_??_d1_??_d2_??_d3) in 2 hr (d0 41%, d1 42%, d2 15%, d3 2%). No exchange was observed for the reaction of pyridine with monodeuteroacetic acid. The conversion-time curves of typical series reactions (d0 → d1→ d2 → d3) were obtained for the fatty acid catalyzed exchange in deuterium oxide. The effect of the fatty acid RCO2H (substrate fatty acid : D2O=1 : 0.86 : 276, mol/mol/mol) on the conversion was in the order of R; C1-C3<C4-C10, where the reaction mixtures were homogeneous in the case of C1-C3 and were heterogeneous in the case of C4-C10. The effects of the initial concentration of the substrates and the catalysts (RCO2H) on the total conversion were studied by using some fatty acids (R; C2, C4 and C9) in deuterium oxide (for 2 hr). The total conversion of the substrate increases with increasing the concentration of the acids. The total conversion decreases in the case of R=C9, but, increases in the case of R=C2 with increasing the concentration of the substrate. In the case of reactions with low concentrations of the substrate, the reactivity was in the order of C9>C4>C2, while with high concentrations, the reactivity was in the order of C4>C2C9 and C9>C4>C2 with high and low concentrations of the acids, respectively. A possible reaction mechanism was proposed and discussed.
The binary mixed monolayers of polyvinyl stearate with various long chain compounds, such as 1-hexadecanol, 1-octadecanol, stearic acid, vinyl and ethyl stearates, have been studied by pressure-area characteristics, with some interests in the resistance of these mixed monolayers to water evaporation. In all cases, the mixed monolayers showed remarkable condensation effect. For the mixed monolayers of polyvinyl stearate with 1-hexadecanol, 1-octadecanol and ethyl stearate, the mean areas per hydrocarbon chain exhibited minima, while the compressional moduli exhibited maxima, in the particular compositions where the mole fractions (monomer unit) of polyvinyl stearate were 0.3 to 0.4. From the data of pressure-area isotherms, the apparent excess free energies of mixing ΔGex were evaluated, using the area and the mole fraction in monomer unit for the polymeric component, on the assumption that each monomer residue behaves independently as a kinetic unit. Negative deviations were largest at nearly the same composition as the above, where the values of ΔGex were obtained in the range of -40 to -80 cal/mole at 20 dynes/cm. On the other hand, for the mixed monolayer of 1-octadecanol with ethyl stearate which can be considered to be equivalent to the repeating unit of polyvinyl stearate, negative deviation was rather small. Thus, the above-mentioned remarkable condensation effect seems to be characteristic of the mixed monolayers in which one component is the comb-like polymer with long side chains while the other is monomeric long chain compounds. It has been considered that the penetration of long chain alcohol or acid into the two-dimensional coil of polyvinyl stearate in the monolayer causes a decrease of the free area of the polymer and closer packing of the hydrocarbon chains of the both components. Contribution of hydrogen bonding between the polar groups seems to be rather small.
The retardation of water evaporation by binary mixed monolayers of polyvinyl stearate with 1-hexadecanol, 1-octadecanol and stearic acid has been studied. The evaporation rate was determined from the progressive increase with time in weight of desiccant (LiCI) suspended from one end of the beam of a balance just above the water surface. The surface pressures were measured simultaneously by the Wilhelmy method. From the measurements with and without a monolayer, the specific evaporation resistance γ which is characteristic of the monolayer was calculated. It was found that the mixed monolayers of polyvinyl stearate with long chain alcohols or acids in a certain proportion suppressed remarkably the evaporation of water, although the specific resistance varied with different spreading techniques. According to the energy barrier theory on the evaporation resistance, for an ideal mixed monolayer, logarithms of the specific resistance, as well as the free energies of activation on water evaporation (ΔG≠), may be expected to be linear functions of the composition. However, the mixed monolayers used in the present work showed marked deviation from the ideal behaviour and in γ-composition curves exhibited maxima. From these results the excess free energies of activation on water evaporation (ΔG≠ex) were evaluated as functions of compositions and these relations were compared with those for apparent excess free energies of mixing (ΔGex) discussed in Part I of this paper. Maximum deviations in both cases of ΔG≠ex (positive) and ΔGex (negative) occur at nearly the same composition, suggesting the close corelation of these two quantities. Condensation effect in the mixed monolayers or closer packing of hydrocarbon chains may contribute to the positive deviation in the activation free energies when molecules of water pass through the monolayers. But the absolute values of ΔG≠ex and ΔGex differ considerably from one another, because ΔGex is concerned with equilibrium state while ΔG≠ex is concerned with activated state for water evaporation process through the monolayer.
Zinc 0, 0-diisobutyldithio [35S] phosphate (ZDDP [35S]) was synthesized in a high yield of 70% by adding radioactive sulfur- [35S] to sodium 0, 0-diisobutyl thiophosphite. The labelled position was discussed by measuring radioactivity of the products from thermal decomposition of ZDDP- [35S]. It was found that two sulfur atoms in ZDDP molecule were not equally labelled by this method. The difference of the radioactivity between the two sulfur atoms was decreased by heating or dissolving. It was postulated that intramolecular exchange of the sulfur atoms in ZDDP occured by heating and dissolving.
Mixed fatty acids synthesized by air oxidation of paraffin were obtained from the Soviet Union. The mixed fatty acids were fractionated to C5-6, C7-9, C14-16 and C17-20 fractions by vacuum distillation, molecular sieve and the other methods, and these fractions were esterified with ethanol by usual method. Then, the nutritive value of the each ester was compared with salad oil fatty acid ethyl ester prepared from commercial salad oil by feedings in Wister strain rats. The rats were fed 10% of each ester or contralled ester mixed with basal diets. As the results, there was no difference between the weight gain of the sample ethyl esters prepared from synthesized fatty acids and the salad oil fatty acid ethyl ester.
Residual quantity of a-tocopherol, BHA and BHT added to oils was examined after purification and hydrogenation processes, and the following results were obtained. 1) α-Tocopherol, BHA and BHT concentration in the oil hardly changed after deacidification, but a large amount of sodium hydroxide slightly reduced the amount of a -tocopherol. 2) α-Tocopherol, BHA and BHT concentration in the oil decreased slightly by use of activated clay for decolorization, and the rate of reduction of BHA and BHT was smaller than a-tocopherol. Use of an adsorbent containing activated carbon increased the reduction rate to a slight extent. 3) BHA and BHT were completely removed from the oil even by treatment at 160°C, the temperature lower than that used for usual deodorization treatment, but 50% of α-tocopherol remained even by treatment at 250°C, althought the decrease became greater at higher temperatures of deodorization treatment. 4) Change in the concentration of α-tocopherol by hydrogenation of the oil depended on the kind of catalyst used, and a-tocopherol concentration decreased in the order of Ni, Ni-Cu, Pd-C, and Cu-Cr catalyst. By the use of a Ni catalyst, concentration of α-tocopherol hardly changed when hydrogenated at an atomospheric pressure, irrespective of temperature, but under a high-pressure, the rate of decrease became greater with increasing temperature. In contrast, concentration of BHA and BHT decreased markedly by the use of Cu-Cr or Cu-Ni catalyst at atomospheric pressure, but the decrease was small under other conditions.