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Soybean oil (SBO) is common commercial vegetable oil. Reusing oil at high temperatures can cause rancidity, and one of the indicators is the presence of free fatty acids. This study aims to investigate changes in the chemical composition of SBO after heating using 1D NMR, 2D NMR, and TD NMR. Soybean oil was heated 8 h per day for 5 days at 190 °C. Total 6 samples were collated and consisted of SBO0 (unheated), SBO1 (heated on the first day) SBO2 (heated on the third day), SBO3 (heated on the third day), SBO4 (heated on the fourth day), and SBO5 (heated on the fifth day). The sample was analyzed by using 1H NMR, PFG NMR, TD NMR. SBO0 and SBO4 by 13C NMR, DEPT 135, and HSQC. 1H NMR spectra showed SBO after heating increase the amount of proton. However, linolenate was decreased and SFA became higher than UFA and PUFA. 13C NMR spectra showed a reduced carbon chain. The correlation between 13C NMR, DEPT 135 showed SBO contained secondary carbon was detected as a negative signal. HSQC showed the carbon in the TAG group interacts strongly with the hydrogen in acyl and methyl groups. PFG NMR and TD NMR results presented that the distribution coefficient decreased, and transverse relaxation times also decreased, indicating a long period of heating increased the mass and viscosity of the oil. NMR is a quick method for analyzing the physicochemical changes of SBO. The longer periods of heating make a different chemical composition and cause oxidative rancidity. [ABSTRACT FROM AUTHOR]

Heating of 5-acetyl-1,3-dimethyluracil in TFA or in acetic acid with the addition of sulfuric acid resulted in ipso-substitution of the acyl group in the molecule. 5-Nitroso-1,3-dimethyluracil was transformed into 1,3,7,9-tetramethylpyrimidopteridine-2,4,6,8-tetraone by heating in TFA. [ABSTRACT FROM AUTHOR]

The interaction of thiotrichlorophosphate with the sodium salt of ricinoleic acid in alcohol-benzene mixtures has been studied. Tris(ricinoleate) thiophosphate has been isolated with high yield (80%). Its composition has been determined. The structure of the product was characterized by the following methods: 1H, 13C, 31P NMR, IR spectroscopy, gel chromatography, and thin-layer chromatography. Based on 31P NMR, it has been shown that the phosphorus surrounding is in the form of trigonal pyramid with the sulfur atom in an axial position. Based on the IR spectroscopy data, the substitution reaction proceeded on the oxygen atom of an acyl group. [ABSTRACT FROM AUTHOR]