Alkali metal peroxides

Alkali metal peroxides are stable under ambient conditions in the absence of water. They dissolve vigorously in water, forming hydrogen peroxide and the metal hydroxide. They are strong oxidizing agents and can react violendy with organic substances. Only lithium peroxide and sodium peroxide have been commercialized. 

Alkali-immobile dye-releasing quinone compounds, 19 293-294 Alkali lignins, 15 19-20 Alkali manganate(VI) salts, 15 596 Alkali manganates(V), 15 592 Alkali-metal alkoxide catalysts, 10 491 Alkali-metal alkoxides, effects of, 14 252 Alkali-metal alkylstannonates, 24 824 Alkali-metal fluoroxenates, 17 329-330 Alkali-metal hydrides, 13 608 Alkali-metal hydroxides, carbonyl sulfide reaction with, 23 622 Alkali-metal metatungstates, 25 383 Alkali-metal perchlorates, 18 211 Alkali-metal peroxides, 16 393... 

Whether the ion pair [(C6H5)2CO 02 "] separates to yield alkali metal superoxide (M02) or collapses to yield alkali metal peroxide (M202) depends upon the stability of the alkali metal superoxide. Thus, in general the yield of superoxide increases as the alkali metal is changed from lithium to sodium to potassium to rubidium, a sequence that parallels the stabilities of the superoxides. Superior yields of superoxides are observed in pyridine solution (Table XI). This is apparently connected with the ability of pyridine to stabilize the superoxide ion by complex formation (25). 

Hydrogen peroxide has been used to bleach soya beans,171 lechitan and phosphatides.172 The alkali metal peroxides are alternative reagents.173 It is also used to decolorize fatty acid sarcosides,174 whilst xanthines require sodium perborate or percarbonate175 and starches require some irradiation.176... 

Hence, it can be concluded that peroxide ions are thermodynamically unstable in high-temperature melts of alkali metal halides. However, in the presence of 02 in the atmosphere over the halide melts they may exist in sufficient concentrations, even at temperatures considerably exceeding that of decomposition of pure alkali metal peroxides. 

The compounds LisM Og = Np, Pu) have been obtained by heating the actinide dioxide with lithium oxide in oxygen at ca. 400°C(Np), and the analogous BaaM NpOe (M = Li or Na) by heating Np03-H20 with the alkali metal peroxide in oxygen above 400 "C. The [NpOg] " anion appears to be octahedral. 

For the decomposition of inorganic samples by soda ash in platinum crucibles, the resistance of platinum is increased in an atmosphere of carbon dioxide. In a nitrogen atmosphere, platinum is corroded less by alkali metals. Peroxide bombs are good for wet ashing to destroy the organic matter in samples like coal. The PTFE acid digestion bomb prevents contamination and insures no losses by volatilization. Samples like coal can be analyzed in quantities of 50 mg or less. 

The other alkali metal peroxides must be heated to higher temperatures (>500 °C) before decomposition occurs. The decomposition of Li202(s) to Li20(s) is thermodynamically favorable because of large differences in the lattice energies of the two solids, but the decomposition may also be assisted kinetically, as suggested below ... 

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