The effect of the structure of cyclic poly (oxyethylene) compounds (crown compounds) on their complexation properties toward alkali metal cations was examined. Introduction of an electron-donating side arm on the crown ring was found to be an effective method for developing a host for a specific cation. A new ion transport system has been developed which incorporates a structural device which assists in the cation release process by using intramolecular complexation of an 18-crown-6 and a primary ammonium ion. Lipophilic monoazacrown ethers selectively transported a specific cation against its concentration gradient by pH control in a liquid membrane. The results obtained in this study demonstrate that an appropriate design of coordination sites markedly affects the complexing ability of host compounds.
Effects of minor components on the oxidative and flavor stabilities of edible fats and oils are discussed. Main components of green pigments in edible vegetable oils are pheophytins a and b. Pheophytins can produce the singlet oxygen to accelerate the oxidative deterioration of oils in the presence of light irradiation as well as chlorophylls. Chlorophylls and their derivatives, however act as a free radical scavenger to inhibit the autoxidation of oils under the dark condition. Carotenoides and tocopherols affect on the photo-and autoxidation of oils, while free fatty acids, mono-, and diglycerides and sterols affect on the flavor stabilities of oils.
A gradient elution HPLC system was devised for the separation and quantification of natural lipids containing cholesterol ester (Ch-E), triglyceride (TG), free fatty acid (FA) and phospholipid (PL) as the major lipid constituents. Standard lipid mixtures were chromatographed into individual classes varying in polarity on a silica column with UV detector (210 nm) by gradient elution using hexane : 2-propanol (100 : 0.15) and methanol : 2-propanol : 85% phosphoric acid (100 : 150 : 2.5) as the mobile phases. Sample sizes of 1050μg fig for neutral lipids (Ch-E, TG and FA) and 200600 μg for polar lipid (PL) were optimum for quantification, and analysis was completed in 40 min. Lipids extracted from human serum (ca. 0.1 mL) could be separated and accurately quantified by the HPLC system under the same conditions, as could also the standard mixture. Lipid compositions of serum lipids as determined by the present HPLC method agreed with those of enzymic methods used in clinical routine.
By a collaborative study, a standard method was established for determining copper, iron, and nickel in vegetable oils by graphite furnace atomic absorption spectrophotometry. One gram of sample was dissolved in 10 mL of isobutyl methyl ketone containing a small amount of nitric acid followed by injecting a 10 or 20, μL aliquot of the solution directly into a graphite furnace for atomization according to a heating program. Atomic absorption signals were measured by a peak height or absorbance mode. Metal content was determined from a calibration curve. This study was conducted at seven laboratories, using various types of equipment and analytical conditions. The data obtained using soybean oil and hydrogenated soybean oil, added with metals at 0.6 ppm, were statistically analyzed. The coefficients of variation were approximately 5% for copper, 18% for iron, and 10% for nickel, respectively. This method is simple and rapid. It will prove useful for the analysis of metals in vegetable oils.
Preparation of dimethyl dodecanedioate in two steps was studied. The first step is the formation of methoxycyclohexyl peroxide by reaction of cyclohexanone with hydrogen peroxide and methanol in the presence of acid catalyst. The second is the dimerization of the resulting methoxycyclohexyl peroxide through the action of iron (II) sulfate to obtain the dimethyl dodecanedioate. In the first step, sulfonic acid in 0.01010.015 mol per mol of cyclohexanone is used as the catalyst. In the second step, the resulting methoxycyclohexyl peroxide can be used for the dimerization without purification. Various iron (II) salts, such as iron (II) sulfate, iron (II) ammoniumsulfate and ferrous chloride, are effective as the reducing reagents. The reaction can be conducted at a temperature below 10°C. Water should be used in excess in the redox reaction, if it is desired to obtain branched dibasic acid dimethyl esters. Cyclopentanone, cycloheptanone and 2-methylcyclohexanone gave the corresponding dibasic acid dimethyl esters, respectively.
The solution properties of concentrated anionic-nonionic mixed surfactant systems were investigated using a polarizing microscope, differential scanning calorimetry (DSC), and fluorescence probing method. The mixed systems were sodium dodecyl sulfate (SDS) -hexadecyl polyoxyethylene ethers (C16POEn, n=6, 10, 20 and 40). Liquid crystals (hexagonal and lamella type s) and a viscous isotropic solution were formed in a concentrated solution of these mixed surfact ant systems. The liquid crystals could be formed more easily by SDS mixing with a nonionic surfactant including shorter polyoxyethylene chain than that having a longer chain. The amount of bound-water between surfactant molecular layers in the concentrated system was maximum at 0.5 molar ratio of SDS. Micropolarity about the hydropilic group of surfactant molecules in the hexagonal phase increased with the mixing of a nonionic surfactant, attaining a maximum at a 0.5 molar ratio of SDS. Hydrophilic-hydrophilic interaction between surfactant molecules was found essential to liquid crystal formation in the concentrated mixed surfactant systems and also to mixed micelle formation in the dilute system.
Removal of glass particles from a glass plate placed in an ultra-centrifuge equipped with angle roter was conducted under various conditions with regard to particle diameter, washing time, and rotations per minute (rpm) of the centrifuge. The contribution of vertical component, Fv of the centrifugal force to removal was assessed at a constant horizontal component, Fh. The following results were obtained. 1) Removal efficiency increased with particle diameter and with washing time, and was proportional to rpm which was in the range 14 × 104 rpm for small particles, and in the range 110 × 103 rpm for large particles. 2) Removal efficiency increased with decrease in Fv at constant Fh, finally reaching maximum efficiency at Fv=0. Removal force attained by centrifugal force F2 (when Fv=0) and that by lamminar flow F1 were essentially the same at 7085% removal.
Urushiol, an important naturally occuring coating material, was synthesized from the readily available 2, 3-dimethoxybenzyl p-tolyl sulfone (1). The synthetic route is shown in Fig.-1. Compound (1) was easily synthesized from 2, 3-dimethoxybenzaldehyde in 3 steps in 73% overall yield as shown in Fig.-2. Treatment of (1) with sodium hydride in DMF followed by addition of organic halides (2) afforded alkylated products (3) in excellent to good yields (see Table-1). The reductive elimination of the sulforiyl group of (3) with 6% sodium amalgam gave 3-alkyl-veratrols (4) in excellent to good yields. Urushiol (5 a) and laccol (5 b) were obtained from the demethylation of 3-alkylveratrols (4 a-b) bearing methoxy groups as protective groups in good yields by treatment with boron tribromide in methylene dichloride. Further, urushiol (5 c-d) having a cis-olefin group in the side-chain was obtained from demethylation of 3-alkynyl-and 3-alkenylveratrols (4 e-f), respectively, by treatment with boron tribromide, followed by partial hydrogenation with Lindlar catalyst.