|WikiProject Chemistry||(Rated Start-class, Mid-importance)|
Useful Addition to Mechanism and Rate: Initiation & Termination are Typicall Spin Forbidden
As a rule, this type of chemical reaction would be much more common (eg; it would affect a significantly larger quantity of the molecules in any system). In reality, this type of process is very rare. Even in systems where air-autoxidation is very likely to occur (such as Diisopropyl ether), the typical process involves the formation of no more than milimoles out of a system composed of moles over the course of 10s or hundreds of days at room temperature and atmospheric pressure, so MAXIMUM parts per thousand relative to the total at the point when we find and remove our rancid oil, cracked rubber, or dangerous solids formed in an old ether bottle. THE REASON is that most organic compounds have singlet electronic configurations and breaking a bond homolytically to form one or more radical species requires that the overall spin of the system NOT be conserved (IF one only consider the explicitly reacting species). In reality, the process typically involves either the presence of a 3rd compound which can, typically catalytically, "sensitize" one or more of the reacting species (which serves the purpose of bringing one or more of the reagents into an excited triplet state through some other pathway), OR the process involves a very specific type of reaction coordinate (such as a 3-body reaction of a particular orientation, frequency factor, etc.) which serves the purpose of coupling the necessary degrees of freedom to allow this type of process to occur. The Result: these reactions occur very rarely at a molecular scale... Thus, oxidation does not destroy everything around us and we need only take precautions to guard against a slow, minimal type of chemical reaction. destructive though it may be. We live in an oxidizing atmosphere with plenty of visible light (which can cleave bonds through photolysis) — Preceding unsigned comment added by 220.127.116.11 (talk) 18:17, 5 November 2012 (UTC)
Nomination for Deletion
I suggest this article be deleted and will nominate it but first wanted to start a discussion. The main reasons are: 1. The page makes no distinction between autooxidation and oxidation. Many if not all of the processes mentioned would be considered regular oxidation reactions, and without a clear definition of autooxidation why have a separate page? 2. The references given are for the mechanism presented (typical oxidation, not exclusive to autooxidation) while the majority of the prose and intro are unsourced. This reinforces the first point, that the information presented on the page does not differentiate at all from typical oxidations and does not require its own page. Eframgoldberg (talk) 16:17, 5 May 2017 (UTC)
One way forward
I agree and disagree, but sympathize. Autoxidation is a common term (thousands of hits in Google and SciFinder), so an article on the topic will be recreated again and again until someone deals with it. And who better than you and I who doubt its usefulness, are skeptical that a straightforward definition exists, and suspect that the current content is poor. What I suggest is that we discard most of the current content and start over by quoting from some major reviews that show that the term is wishy washy.
I searched ChemAbs for "autoxidation" (>11000 hits) and then for reviews (hundreds mention the term) and then picked highly cited reviews with the term in the title. Here are two findings: Mechanisms for the autoxidation of polyunsaturated lipids" By Porter, Ned A. From Accounts of Chemical Research (1986), 19(9), 262-8. "Lipid peroxidation is a complex process in which molecular oxygen and lipid react by a free-radical chain sequence. This process, known as autoxidation in purely chemical systems, leads to the degradation of naturally occuring fats and oils, ... processes which lead to degradation of natural compounds such as rubber, waxes, and other lipids."
- Miller, Dennis M.; Buettner, Garry R.; Aust, Steven D. From Free Radical Biology & Medicine (1990), 8(1), 95-108.
"Nevertheless, several biomolecules ... have been reported to react directly with dioxygen, producing O2. or H202 or both. RH2 + 02 → RH. + O2- + H+ RH2 + 02 → R + H202 These types of reactions are termed "autoxidations," defined as the "...apparently uncatalyzed oxidation of a substance exposed to the oxygen of the air . . . ".~9 However, since it is unlikely that the direct reaction of dioxygen with these biomolecules occurs at significant rates, a catalyst, such as a transition metal, is needed...°"
- The Molecular Mechanism of Autoxidation for Myoglobin and Hemoglobin: A Venerable Puzzle" Shikama, Keiji
From Chemical Reviews (Washington, D. C.) (1998), 98(4), 1357-1373. "Like all known dioxygen carriers synthesized so far with transition metals, the oxygenated forms of myoglobin and hemoglobin are oxidized easily to their ferric met forms, which cannot be oxygenated and are therefore physiologically inactive. The mechanistic details of this autoxidation reaction,"
At least those are some ideas. The main problem is that the term is used widely and wildly perhaps.