Peroxidate ion

Analytical Methods. Analysis of fresh and spent peroxides and superoxides is done by adding the material to water. Approximately 0.1 wt % permanganate is used in the water to decompose the peroxide ion which otherwise forms. The evolved oxygen is measured volumetricaHy. If the material is spent, the base strength is titrated to a phenolphthalein end point, acidified further, and the carbon dioxide is deterrnined volumetricaHy. 

Zirconium carbide is inert to most reagents but is dissolved by hydrofluoric acid solutions which also contain nitrate or peroxide ions, and by hot concentrated sulfuric acid. Zirconium carbide reacts exothermically with halogens above 250°C to form zirconium tetrahaHdes, and with oxidizers to zirconium dioxide in ak above 700°C. Zirconium carbide forms soHd solutions with other transition-metal carbides and most of the transition-metal... 

The peroxides M2O2 contain the peroxide ion 02 which is isoelectronic with F2. Li202 is prepared industrially by the reaction of Li0H.H20 with hydrogen peroxide, followed by dehydration of the hydroperoxide by gentle heating under reduced pressure ... 

Deprotonation of H2O2 yields OOH , and hydroperoxides of the alkali metals are known in solution. Liquid ammonia can also effect deprotonation and NH4OOH is a white solid, mp 25° infrared spectroscopy shows the presence of NH4+ and OOH ions in the solid phase but the melt appears to contain only the H-bonded species NH3 and H202. " Double deprotonation yields the peroxide ion 02 , and this is a standard route to transition metal peroxides. 

Oxygen is ordinarily assigned an oxidation number of —2 in its compounds. (An exception arises in compounds containing the peroxide ion, 022-, where the oxidation number of oxygen is —1.)... 

Using MO theory, predict the electronic structure, bond order, and number of unpaired electrons in the peroxide ion, 022-. 

There are no unpaired electrons. These conclusions are in agreement with the Lewis structure of the peroxide ion ( Q—O )2. ... 

Write the complete Lewis structure for each of the following compounds (a) zinc cyanide (b) potassium tetrafluoroborate (c) barium peroxide (the peroxide ion is 022-). 

Reaction of alkyl and acyl halides with peroxide ion... 

It should be noted that the superoxide ion O2 and peroxide ion 0 " are different,... 

Synthesis of all four 8,8a-secobenzophenanthridine alkaloids was carried out chiefly by Baeyer-Villiger oxidation of appropriate benzophen-anthridines (Scheme 32). Thus, arnottianamide (206) was obtained from chelerythrine (210) (172,175), iwamide (207) from N-methyldecarine (211) (168,172), integriamide (208) from avicine (212) (171,172), and isoarnottiamide (209) from nitidine (213) (172,175). The proposed mechanism of this reaction (168,172,175) consists of initial attack of the peroxide ion on the C=N+ double bond followed by rearrangement and hydrolysis. 

Although this reaction shows the formation of 02 +, it is also possible to add one electron to the 02 molecule to produce (),, the superoxide ion, or two electrons to form O/, the peroxide ion. In each case, the electrons are added to the antibonding 7r orbitals, which reduces the bond order from the value of 2 in the 02 molecule. For ()2 the bond order is 1.5, and it is only 1 for 022-, the peroxide ion. The 0-0 bond energy in the peroxide ion has a strength of only 142k) moT1 and, as expected, most peroxides are very reactive compounds. The superoxide ion is produced by the reaction... 

Reduction of a chemical species involves the gain of electrons by that species. Because the solutions of alkali metals in liquid ammonia contain free electrons, they are extremely strong reducing agents. This fact has been exploited in a large number of reactions. For example, oxygen can be converted to superoxide or peroxide ions. 

The larger, less polarising, Na+ cation is able to accommodate enough of the bigger peroxide ions (0221 to form a stable lattice (1). The smaller, more polarising, Mg2+ ion forms a more stable lattice with the () ion (1). 

The ground state (0 kJ/mol) for the CL molecule is represented by the term symbol 3v . The first excited state (92 kJ/mol above the ground state) is a 1 singlet (electrons spin paired with both electrons in either the n x or the n y level). The 1 v state with paired spin electrons, one each in the 7i v and n y levels, is the next excited level 155 kJ/mol above the ground state. Reduction of 02 by one electron yields the superoxide ion (02), a radical anion. Reduction by two electrons yields the peroxide ion, (02 ). Bond lengths and bond orders for these are given in Table 4.2. As noted in equation 4.2, the reduction potential for 02 in the presence of protons is thermodynamically favorable. Therefore, reversible binding of O2 to a metal can only be achieved if competition with protons and further reduction to superoxide and peroxide are both controlled.8... 

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