Ground-state molecular oxygen

Further, the thio-olefin co-oxidation (TOCO) radical chain reaction (cf Chapter 9.11.9.3.3) using ground state molecular oxygen was employed to synthesize a series of benzo-fused cyclic peroxy ketals 232 in good yield (Scheme 64) <2006T4120>. 

The bond orders for ground-state molecular oxygen (dioxygen, 02), for superoxide ion (02 -), and for (HOOH) are 2, 1.5, and 1, respectively. Tabled provides molecular orbital diagrams for dioxygen ( g , Ag, and g+) and superoxide ion, which illustrates the biradical character of 62 (-02-) and the delocalized spin density of 02 - (one-half spin per oxygen). 

The reaction of ground-state molecular oxygen with S(IV) proceeds at very slow rates in the absence of light or specific catalysts. Transition metals, such as Fe(III), which are capable of coordinating S(IV) and/or 02 accelerate the rate of S(IV) autoxidation. The mechanisms invoked to explain transition-metal-catalyzed S(IV) autoxidations can be classified into two categories (1) one-electron free-radical reactions and (2) two-electron polar reactions involving ternary complexes comprised of the transition metal, S(IV), and molecular oxygen. 

Molecular Oxygen Ground State and Excited State... 

Selected theoretical and computational photochemistry references.135 136 136 Ground-state Molecular Oxygen... 

Ground-state molecular oxygen (dioxygen), an open-shell triplet (biradical) denoted by spectroscopists 35, is one of the most abundant and important life-supporting species on Earth. It can participate in some photochemically initiated reactions, sometimes called... 

Ozone is a specific atmospheric pollutant characteristic of urban and some industrial areas of the troposphere. Its concentration is very variable. Because of both the photochemical character of the origin of ozone and its high reactivity with organic atmospheric pollutants as well as some organic materials on the Earth s surface, its night concentration drops to zero. Only ground state molecular oxygen attacks rubber in this period of the day, but mechanically initiated processes and reactive ozonation intermediates and products remain involved. 

Energy transfer, with spin conservation, to ground state molecular oxygen ( ,02) to form singlet oxygen (Equation 2.14) — termed type II reaction... 

Ozone photolysis in the upper atmosphere is extremely rapid. Recent experiments [304, 689] have suggested that, in the presence of ground state molecular oxygen, the singlet production occurs mainly by the energy transfer process ... 

This is a particularly interesting reaction, since in the first stage the anthracene molecule is excited to the triplet state and produces singlet oxygen from ground-state molecular oxygen, and then finally forms an endoperoxide. 

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