Nitrous spectrum

In aqueous solutions of sulphuric (< 50%) and perchloric acid (< 45 %) nitrous acid is present predominantly in the molecular form, although some dehydration to dinitrogen trioxide does occur.In solutions contairdng more than 60 % and 65 % of perchloric and sulphuric acid respectively, the stoichiometric concentration of nitrous acid is present entirely as the nitrosonium ion (see the discussion of dinitrogen trioxide 4.1). Evidence for the formation of this ion comes from the occurrence of an absorption band in the Raman spectrum almost identical with the relevant absorption observed in crystalline nitrosonium perchlorate. Under conditions in which molecular nitrous... 

The proton NMR spectrum shows chem shifts of 6.93 5.957- (Ref 1). Photolysis with a Hg arc lamp gives N, nitrous oxide, methane, and ethane (Ref 2). It was found to produce colon and rectal carcinomas in rats after oral administration at 12mg/kg weekly, induction period 235 days (Ref 3)... 

A symmetric spectrum with g = 2.003 0.001 and All 3 G has been observed when oxygen or nitrous oxide is adsorbed on Ti02, Sn02, and ZnO. Although this spectrum was assigned to the O- species by Kwan (4-7) and later by van Hooff 48), it is inconsistent with the theoretical spectrum, making the assignment doubtful. 

Treatment of cordycepin with nitrous acid, and subsequent hydrolysis of the deaminated product, yields hypoxanthine, indicating that in the adenine moiety the primary amino group is free and the glycosidic linkage involves C7 or C9. The close similarity between the ultraviolet absorption spectrum of cordycepin and those of 9-methyladenine and adenosine63 (9-/3-J>-ribofuranosyladenineMa) favors the latter possibility. The complete stereoisomeric description of cordycepin (XXVIII), formulation of which... 

A yellow solution is formed when nitrous acid is added to thiosulphate ion in water84. This is believed to be due to the formation of nitrosyl thiosulphate [O3SSNOI, although this has not been isolated and even in solution decomposition is fairly rapid. The equilibrium constant for its formation Wxno is 1.66 x 107 dm6 mol 2 at 25 °C and the UV-visible absorption spectrum is very similar to that of other S -nitroso compounds85. The rate constant for its formation is very large and is believed to represent a diffusion controlled process. Thiosulphate ion does appear to catalyse nitrosation but, over the range studied... 

Fox Talbot (24), an English scientist, found in 1834 that, with the aid of a prism, he could distinguish lithium from strontium, even though the salts of both give red flames (4, 26, 32). He stated that the dark lines previously observed by Sir David Brewster (33) in the spectrum of light which had passed through vapors of nitrous acid were caused by absorption of light (5,25). 

Figure 4.14 shows the absorption spectrum of gas-phase nitrous acid and Table 4.13 gives absorption... 

Selwyn, G., J. Podolske, and H. S. Johnston, Nitrous Oxide Ultraviolet Absorption Spectrum at Stratospheric Temperatures, Geophys. Res. Lett., 4, 427-430 (1977). 

The UV spectrum of nitrite at acidic pH is unusual. Nitrite at neutral to alkaline pH has a single peak at 356 nm, which is converted to a series of multiple peaks at acidic pH (Fig. 15). Normally, a UV peak is broadened by a combination of vibrational and more closely spaced rotational quantum states. However, light in the near UV region can separate nitrous acid into hydroxyl radical and nitric oxide. 

The other copper-only binuclear centre to be considered is the CuA or purple copper complex. It is part of the terminal oxidase in mitochondrial respiration, cytochrome c oxidase (COX). Its EPR signature, a seven-line spectrum, has since long been known to be different from the classes type 1 to 3 and arises from two copper ions in a 1.5 valence (or mixed valence) state, first proposed from EPR-analysis of a similar center in nitrous oxide (N20) reductase. There is a close correspondence between the blue and purple states of copper since each of the two copper ions in CuA can be considered as being structurally related to the mononuclear blue site coordination. 

Nitrous oxide and carbon dioxide have the same number of electrons and their linearity might be expected to make resolution of the spectrum and its interpretation possible. Nevertheless there are still uncertainties although much progress has been made. 

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