Tetramethylammonium Superoxide

Dining the preparation by solid phase interaction of tetramethylammonium hydroxide and potassium superoxide [1] by tumbling for several days in a rotary evaporator flask, a violent explosion occurred [2], This may have been caused by ingress of grease or other organic material leading to contact with potassium superoxide, a powerful oxidant. 

Caution. The use of predried tetramethylammonium hydroxide penta-hydrate has resulted in a serious explosion during the solid-phase metathesis of potassium superoxide with tetramethylammonium hydroxide pentahydrate. This can be avoided by using the pentahydrate as supplied without drying and by employing an increased amount of potassium superoxide. The latter can easily be separated during the liquid ammonia extraction. 

Commercially available potassium superoxide and tetramethylammonium hydroxide pentahydrate from Aldrich were used as supplied without further purification. Industrial-grade nitrogen gas does not require any further purification, but the ammonia gas, 99.999%, should be at a minimum purged through Drierite before use. AU work is done under a nitrogen flow unless otherwise stated. 

The yellow ONOO- ion can be made in pure form by passing NO through a solution of tetramethylammonium superoxide in ammonia56 ONOO from other syntheses can be contaminated by reactants and nitrate. ONOOH is a weak acid with a pKa near 6.8 and isomerizes to N03 and H+ in seconds.57 At pH 12 the anion is stable for several hours at 0°C. It occurs solely as the cis isomer, due to a partial double bond between N and the first peroxide O.58 Peroxynitrite is toxic in vivo it is formed through the diffusion-controlled reaction of 02 with NO-.57 ONOOH oxidizes via direct and indirect pathways.59 Under physiological conditions the main reaction partners for ONOO" and ONOOH appear to be carbon dioxide60 and thiols,61 respectively. The ONOO—C02—adduct nitrates tyrosines. 

Tetramethylammonium cw-peroxonitrite, which decomposes at 383 K, is prepared by reacting tetramethylammonium superoxide with nitric oxide in liquid ammonia at 195... 

The most common addition reaction is to a carbonyl group without an adequate leaving group. Examples include the reaction of HO and 02 with CO2 and quinones. A common feature of these reactions is the formation of an adduct that is sufficiently stable to be isolated or characterized (see Scheme 18). The same orange-colored species results from the reaction of solid tetramethylammonium superoxide with gaseous CO2 and with neat CCLt, and is believed to be an anion radical, 000(0)0 . ... 

Tetramethylammonium amide, 1782 Tetramethylammonium azidocyanatoiodate(I). 2006 Tetramethylammonium azidocyanoiodate(I). 2005 Tetramethylammonium azidoselenocyanatoiodate(I), 2007 Tetramethylammonium chlorite, 1742 Tetramethylammonium diazidoiodate(I). 1750 Tetramethylammonium monoperchromate. 1745 Tetramethylammonium ozonate, 1753 Tetramethylammonium pen tall uoroxenoxide. 1747 Tetramethylammonium pentaperoxodichromate, 3103 Tetramethylammonium periodate. 1749 Tetramethylammonium superoxide, 1751 Tetramethylbis(trimethy silanoxy)digold, 3382... 

Superoxides. The action of oxygen at pressures near atmospheric on K, Rb or Cs gives yellow to orange crystalline solids of formula MOz. Na02 can be obtained only by reaction of Na202 with 02 at 300 atm and 500°. Li02 cannot be isolated and the only evidence for it is the similarity in the absorption spectra of the pale yellow solutions of Li, Na and K on rapid oxidation of the metals in liquid ammonia at —78° by oxygen. Alkaline-earth, Mg, Zn and Cd superoxides occur only in small concentrations as solid solutions in the peroxides. Tetramethylammonium superoxide has been obtained as a yellow solid (m.p. 97°), which dissolves in water with evolution of 02. There is clearly a direct correlation between superoxide stability and electropositivity of the metal concerned. 

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