Activation energy of various polymorphisms of monoglycerides was measured by the use of DTA and DSC, and examinations were made on the correlation between transition process among polymorphs and length of molecular chain and crystal growth. 1) Calculation of activation energy from DSC is difficult to obtain the true value because it is highly affected by the rate of temperature rise. If the values are obtained from DTA curves by Kissinger's method, the values are hardly affected by measurement conditions. 2) Activation energy of transition from sub-α to β type is greater than that from α to β type. 3) Activation energy of transition between polymorphs decreased as follows : sub-α→α>α→β type. 4) A simple linear relationship was found to be established between the number of carbon and activation energy.
α- and δ-Tocopherols were oxidized with p-benzoquinone according to the method by McHale and Green or with cupric palmitate. The dimeric oxidation products were then isolated by preparative thin layer chromatography. UV absorption, IR absorption, mass and NMR spectra of the isolated products were determined. Autoxidation of hydrogenated whale oils with these tocopherol dimers was measured by Active Oxygen Method. Two kinds of oxidized tocopherol dimers were produced during the oxidation of α- and δ-tocopherols. One is the dimers derived from the oxidation of α- and δ-tocopherols with cupric palmitate (α-2 & δ-3), having phenolic hydroxyl group. Another is the dimer obtained from the p-benzoquinone oxidation products of α-tocopherol (p-1), having no phenolic hydroxyl group. The hydroxyl dimers indicated antioxidative power, especially the dimer derived from the oxidation of δ-tocopherol (δ-3) had a strongly antioxidative property although its activity was less than that of δ-tocopherol. The hydroxyl dimer of α-tocopherol (α-2) had only a small effect on the protective action against the oxidation of hydrogenated whale oil, while the dimer (p-1) did not have antioxidative activity. From the structural study of δ-3, this had the following formula :
Diacetoxystearic acid (DAS) was obtained directly from oleic acid with peracetic acid or a mixture of hydrogen peroxide and acetic acid in the presence of an acid catalyst. The conditions of the reaction were investigated. Water in the reaction mixture decreased the yield of DAS. Maximum yield of DAS (82%) was obtained under conditions that a 5 : 1.2 : 0.15 (mol) mixture for acetic acid, peracetic acid and H2SO4 was added dropwise to 1 mol of oleic acid, and the reaction mixture was heated 95°C for 3hr.
A 4-methylsterol was isolated from the unsaponifiables of rice-bran oil by preparative thin-layer chromatography (TLC), and identified as cycloeucalenol [4α, 14α-dimethyl-9, 19-cyclopropane-24 (28) -methylene cholestan-3β-ol] by TLC, IR, NMR and combined GC-MS, the occurrence of which in rice-bran oil had not yet been reported. The cycloeucalenol and its acetate showed mp 141142°C and 110111°C, respectively. Cycloeucalanol derived from the cycloeucalenol by hydrogenation and its acetate showed mp 147-148°C and 112113°C, respectively.
Previously (1962), the authors have separated a new 4-methyl sterol, named “gramisterol”, from the unsaponifiables of wheat germ oil by column chromatography. Its structure was presumed to be 4α-methyl-Δ7, 24 (28) -ergostadien-3β-ol. Later (1964 and 1965), Schreiber et al. reported the presence of 24-methylene lophenol in potato leaf and sugar cane. The 24-methylene lophenol might be considered to be identical with gramisterol, because the former has the structure of 4α-methyl-Δ7, 24 (28) -ergostadien-3β-ol, that was given for the latter. Since the 24-methylene lophenol in those plants has not been isolated in a pure state, authors attempted in this study to isolate gramisterol (24-methylene lophenol) in a high state of purity from the unsaponifiables of wheat germ oil by preparative thin-layer chromatography, and confirmed by TLC, IR, NMR and MS that the previously supposed structure for gramisterol was correct. Purified gramisterol showed mp 162163°C, [α] D+2.9°, and its acetate, mp 132134°C, [α] D+24.3°. Formerly separated gramisterol was found to contain citrostadienol as impurity.