Autoxidation of methyl linoleate initiated by the ozonide of allylbenzene

Abstract

Allylbenzene ozonide (ABO), a model for polyunsaturated fatty acid (PUFA) ozonides, initiates the autoxidation of methyl linoleate (18:2 ME) at 37 degrees C under 760 torr of oxygen. This process is inhibited by d-alpha-tocopherol (alpha-T) and 2,6-di-tert-butyl-4-methylphenol (BHT). The autoxidation was followed by the appearance of conjugated diene (CD), as well as by oxygen-uptake. The rates of autoxidation are proportional to the square root of ABO concentration, implying that the usual free radical autoxidation rate law is obeyed. Activation parameters for the thermal decomposition of ABO were determined under N2 in the presence of radical scavengers and found to be Ea = 28.2 +/- 0.3 kcal mol-1 and log A = 13.6 +/- 0.2; kd (37 degrees C) is calculated to be (5.1 +/- 0.3) X 10(-7) sec-1. Autoxidation data are also reported for ozonides of 18:2 ME and methyl oleate (18:1 ME).

Formation of secondary ozonides from the reaction of an unsaturated phosphatidylcholine with ozone

“…For experiments where OPPC was exposed to ozone for 1 h, the amount of starting material consumed, determined by HPLC, was identical with the loss of the methyl oleate as determined by transesterification of the reaction mixture, which indicates only the olefin moiety of the phosphatidylcholine was destroyed by ozone. For experiments where the reaction of OPPC was brought to 100% completion, the NMR signals due to the vinyl protons (m, 2 , = 5.31 ppm) and allylic methylene protons (m, 4 , = 1.97 ppm) of OPPC completely disappeared, and a new set of multiplets (2 , = 5.17 ppm, J = 4.8 Hz) was observed. The latter are similar to those of the isomeric (cis/trans) mixture of the methyl oleate ozonides (q, 2 , = 5.17 ppm, J = 4.8 Hz) recently assigned by Ewing and co-workers (24) to the methine protons attached to the 1,3,5-trioxolane ring of the secondary ozonide (35). When the product mixture was separated by HPLC into peak fractions labeled A and B in Figure IB, the chemical shift of these protons was found to be slightly different for the two products, A ( = 5.19 ppm) and B ( = 5.14 ppm).…”

Influence of Storage Temperature on the Composition and the Antibacterial Activity of Ozonized Sunflower Oil

“…It is well known that carboxylic acids are by-products of the ozonolysis reaction (Omonov, Kharraz, and Curtis 2011). They can be formed by oxidation of the aldehydes which are produced during the cleavage of the double bond of olefins (Killops 1986) or during the thermal degradation of ozonides (Cataldo 2013(Cataldo , 2015bEwing et al 1989;Perkins, Roden, and Pryde 1975). As there are still some unsaturations in the ozonized oil, aldehydes can also be formed during the thermal oxidation of unsaturated fatty acids (Roman et al 2013).…”

A new mechanism for ozonolysis of unsaturated organics on solids: phosphocholines on NaCl as a model for sea salt particles

“…[27][28][29][30][31] band is formed at B1110 cm À1 that is characteristic of the peroxide C-O bond 32,33 of the secondary ozonide ring (1,2,4-trioxolane, SOZ) known to be formed in ozone-alkene reactions. 14,[34][35][36][37][38][39][40] New bands at B1385 and 1347 cm À1 are also assigned to the SOZ. 31,33 The peak at 1210 cm À1 is assigned to a C-O moiety, although the specific species is not known.…”