Epoxidation of three fatty acid methyl esters (FAMEs) were carried out with peroxyacid catalysts to investigate the influences of the alkenyl structure on the epoxidation efficiency and selectivity.

A silica-supported peroxycarboxylic acid oxidant, 2-percarboxyethyl silica (SiO2@(CH2)2COOOH), was successfully prepared and used for the epoxidation of fatty acid methyl esters (FAMEs) and vegetable oils. Among the oxidants prepared under different conditions, C-SiO2@(CH2)2COOOH (TEOS:CTES = 2:1) had the highest surface area, pore volume, and peroxide value. It also exhibited the highest activity for the epoxidation reactions. For methyl linoleate, 92.76% yield of epoxidized product was obtained at room temperature. Other unsaturated FAMEs with 1 and 3 double bonds were also efficiently converted to their epoxides. Moreover, the oxidant was also successfully applied to the epoxidation of vegetable oils, olive oil, and linseed oil with high product yield at room temperature. Finally, the used oxidant was regenerated through a simple oxidation process with H2O2 and recycled at least 5 times without much drop in the reactivity.

An active heterogeneous, namely molybdenum acetylacetonate complex immobilized on expanded corn starch (ECS-MoO 2 (acac) 2 ), was prepared and its catalytic activity for epoxidation of stillingia oil with tert-butyl hydroperoxide (TBHP) was investigated. The heterogeneous catalysts were characterized using inductively coupled plasma optical emission spectrometry, Fourier transform infrared spectra, thermogravimetry and differential thermal analyses, scanning electron microscopy, N 2 adsorption-desorption and X-ray photoelectron spectroscopy. By using this catalyst, an environmentally benign process for epoxide production in a heterogeneous manner was developed. The catalyst could be recovered easily and reused without significant degradation in activity for at least 5 times. Graphical AbstractEpoxidation of stillingia oil was catalysed by ECS-MoO 2 (acac) 2, presenting high selectivity towards the epoxide as well as excellent catalytic recyclability.

The L-ascorbic acid can reduce the nitrite to nitric oxide, but the elevated nitrite-to-L-ascorbic acid ratio predisposes to the formation of potentially carcinogenic N-nitroso compound. We study the chemicals which nitrite reacted to L-ascorbic acid with an elevated L-ascorbic acid-to- nitrite ratio in the solution. The products, when the nitrite reacted with L-ascorbic in the solution, were nitric oxide (NO), dinitrogen monoxide (N2O) and nitrogen gas (N2). We give advice that it maybe useful to understand the products which nitrite reacts with L-ascorbic acid in the human beings and other organisms.