Nitrite organic extractions

For the over-the-counter formulations, two of the thirty-nine items tested contained TEA responsive materials. For these tvo instances, exposure of the organic extracts to glacial acetic acid alone led to the complete disappearance of the TEA responsive materials (34). This observation suggests that the unknown materials are probably not simple N-nitroso derivations, and the results are more compatible with their being O-nitroso compounds (nitrites) (34h... 

Iodide can be determined spectrophotometrically (after oxidation to iodine), either as the blue iodine-starch adsorption compound, or as coloured organic extracts containing iodine. Iodide is oxidized to iodine with nitrite or iron(III). 

Matsunaga et al. [146] have also described a similar procedure for the determination of nitrite in seawater. To 500 ml of sample is added 10 ml of sulfanilamide (1% solution) in 2M hydrochloric acid and 5 ml aqueous N-l-naphthylethylene-diamine hydrochloride (0.1%). After 10 min, 5 ml of aqueous dodecylbenzenesulfonate (0.5%) is added and the mixture extracted for 2 min with 50 ml of carbon tetrachloride. Then 75 ml of acetone and 10 ml of 0.1 M hydrochloric acid are added to the separated organic layer and the azo dye... 

Dibromo-biphenyl-2,2 -diamine (14.6 mmol) was suspended in 16 ml of 16% aqueous hydrochloric acid at 0°C and treated with sodium nitrite (31.9 mmol) while maintaining the temperature at 0°C. After an additional hour of stirring 5 ml of KI solution (30.1 mmol) was added dropwise to the reaction mixture at — 10°C. The reaction mixture was slowly warmed to ambient temperature and then heated to 50°C for 2 hours. It was then cooled to ambient temperature and basified with 90 ml of 10% aqueous NaOH and the product extracted into diethyl ether. The organic layer was washed with brine, dried with anhydrous MgSC>4, and concentrated. After purification by chromatography using hexane 1.4 g of product was isolated as an off-white solid, mp = 89°C. 

Experiments suggested a potential cesium-stripping problem in the CSSX process due to the presence of nitrite in the waste stimulant. The true reason for the cesium-stripping problem was, in fact, the presence of surfactant (sodium mono- and dimethyl naphthalene sulfonate) that can partition into the organic phase on extraction and then retain cesium upon stripping. To overcome this drawback, the authors proposed a caustic wash with a moderate concentration of sodium hydroxide sufficient to remove enough of these lipophilic anions to rejuvenate the solvent, therefore,... 

Over a period of 10 min 860 ml of concentrated hydrochloric acid are added to a suspension of 340.0 g of methyl N-isobutyl-p-aspartate in 860 ml of water whilst stirring. The solution is cooled to 0°C and 128.0 g of sodium nitrite dissolved in 280 ml of water are introduced over a period of 1 h 20 min. The reaction mixture is stirred for 2 h at 0°C and extraction is then carried out thrice with a total of 3000 ml of diethyl ether. The organic phase is thrice washed with a total of 1500 ml of water, dried over magnesium sulfate and the ether evaporated under reduced pressure. The residue, when dissolved in a mixture of 1400 ml of petroleum ether and 230 ml of ether, gives, after cooling to 3°C, 325.0 g of methyl N-isobutyl-N-nitroso-p-aspartate, melting point 95°C. 

The diazotization of the amines is carried out in the usual manner. The volume of water is kept at a minimum since the success of the reaction depends in part on the efficiency with which the unstable intermediate is extracted from the aqueous layer by the organic liquid. Either the previously prepared amine hydrochloride is employed or a paste of the hydrochloride is prepared by dissolving the amine in concentrated hydrochloric acid and then cooling rapidly with stirring. For diazotization a nearly saturated solution of sodium nitrite (1 g. in 2 cc. of water) is used. Little work has been done with very weakly basic amines in the diazo reaction.48 In one instance, the base, l-nitro-2-naphthylamine, was diazotized by means of nitrosylsulfuric acid in sulfuric acid benzene was added and then sodium hydroxide until the mixture was slightly alkaline.49 For the very weak bases, the nitrosoacetyl reaction is recommended, since it is carried out entirely under anhydrous conditions. 

The earliest approaches to measuring the concentration of nitrate and nitrite rehed on the conversion to a highly colored azo dye. Initial approaches to analysis of the isotopic content of nitrate and nitrite relied on similar conversion followed by extraction of the dye into an organic solvent in a separatory funnel. The organic phase was then removed, evaporated and the extracted dye analyzed for isotopic content (Olson, 1981 Schell, 1978 Wada and Hattori, 1972). The extraction was... 

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