The Mechanism of Alkane Oxidation by Ozone

Abstract

The characteristics of the initial step in the reaction of ozone with saturated hydrocarbons have been investigated. Ozonation of cyclohexane gives initially cyclohexanol and cyclohexanone in a 3:1 ratio. Cyclohexane is oxidized 4.5 times more rapidly than cyclohexane-d 12 . The relative reactivity of primary, secondary, and tertiary hydrogens is approximately 1:13:110. The ozonation of tertiary hydrogens to tertiary alcohols occurs with 60 to 70% retention of configuration. The presence of good hydrogen atom donors, antioxidants, and a number of other reagents has only a small effect on the percent retention of configuration. These results and others are compared with those obtained for other hydrocarbon reactions, and a mechanism for the ozonation is suggested. Asa result of our interest in the mechanism of biological oxidations of saturated hydrocarbons (II), we have investigated the mechanisms of several alkane oxidations (12, 13). This paper reports our studies on the oxidation of saturated hydrocarbons by ozone. Although there are frequent references in the literature to the oxidation of alkanes by ozone(2), the mechanism of the reaction has received relatively little study.Durland and Adkins (7) reported that cis-and Jrans-Decalin are oxidized in reasonable yield to tertiary alcohols with retention of configuration.Schubert and Pease (24) studied the gas-phase ozonation of alkanes at room temperature and suggested that the products arose from the forma tion and further reactions of RO' and HOO*. A complicating feature in these investigations was the necessity to carry out the oxidation to rela tively high conversions so that the products could be analyzed. Since 15 Downloaded by MICHIGAN STATE UNIV on February 19, 2015 |

Formation of hydrotrioxides during ozonation of hydrocarbons on silica gel. Decomposition of hydrotrioxides

“…[1][2][3][4] HTs including a wide range of O-and Si-containing compounds (alcohols, ethers, acetals, aldehydes, silanes, etc.) have been synthesized and examined since then.…”

The mechanism of oxidation of acetals by ozone. I. Stoichiometry, order of the reaction, solvent effects, and substituent effects

“…Ozone attack on oxygen (Scheme 3c) is similar to that proposed for the ozonation of certain amines (18), and ethers (12). Finally, radical mechanisms (Scheme 3d) have been proposed for the ozonation of certain hydrocarbons (19)(20)(21) and alcohols (21) as well as ethers at high temperatures (1 1).…”

Peroxide intermediates of oxidation processes: Organic trioxides

“…Studies on the properties of HOOO • revealed that the hydrotrioxy radical is a very labile species that, with high probability, decays at the HO-OO • bond. For this reason, no formation of trioxides was observed in liquid-phase oxidation of aliphatic hydrocarbons with ozone, whereas the role of ozone is likely to be limited to initiation of free radical processes according to Scheme 3 56 . Under conditions that stabilize the trioxy intermediate, the formation of hydrotrioxides is assumed 14,57,58 to involve HOOO • (and/or its conjugate anion HOOO − ) (Scheme 6).…”