Nitrites and Nitroso Compounds

Characteristic IR-Absorption Bands of Nitrites and Nitroso Compounds (in cm... 

Verdu E, Viani F, Ajmstrong D (1994) Effect of omeprazole on intragastric bacterial counts, nitrates, nitrites and nitroso compounds. Gut 35 455-460... 

Many compounds have been tested as ignition quality improvers—additives which shorten the ignition delay to a desirable duration. An extensive review in 1944 (6, 43) listed 303 references, 92 dealing with alkyl nitrates and nitrites 61 with aldehydes, ketones, esters, and ethers 49 with peroxides 42 with aromatic nitro compounds 29, with metal derivatives 28 with oxidation and oxidation products 22 with polysulfides 16 with aromatic hydrocarbons nine with nitration and four with oximes and nitroso compounds. In 1950, tests at the U. S. Naval Engineering Experiment Station (48) showed that a concentration of 1.5% of certain peroxides, alkyl nitrates, nitroaikanes, and nitrocarbamates increased cetane number 20 or more units. 

Elimination of NO and NO2 is observed in the photochemistry of a range of nitro and nitroso compounds, nitrites and nitrates. 

Elimination of NO and NO2 is observed in the photochemistry of a range of nitro and nitroso compounds, nitrites and nitrates. The photochemical reactions of aromatic compounds with tetranitromethane and other related reagents have been reviewed. These reactions proceed in the simplest cases by addition of the elements of tetranitromethane to the arene, e.g. to give nitro trinitromethyl adducts, but large numbers of other products can be formed by a diverse range of multistep sequences. 

Incompatible with strong oxidizers acids, water (slowly decomposes, forming amine and carbon disulfide). Reaction with nitrosating compounds (i.e., nitrogen oxides, nitrosyl chloride, nitrite esters, metal nitrates and nitroso compounds, etc.) can cause the formation of carcinogenic N-nitrosodiethylamine. 

Nitro-and Nitroso-Compounds, Nitrates and Nitrites 17.2. Nitro-compounds... 

N-Nitrosodiethylamine. Add 36-5 g. (51-5 ml.) of diethylamine slowly to the calculated quantity of carefully standardised 5A-hydra chloric acid cooled in ice (1). Introduce the solution of the hydi ochloride into a solution of 39 g. of sodium nitrite (assumed to be of 90 per cent, purity) in 45 ml. of water contained in a 250 ml. distilling flask. Distil the mixture rapidly to dryness. Separate the yellow upper layer of the nitrosamine from the distillate saturate the aqueous layer with soUd potassium carbonate and remove the nitroso compound which separates and add it to the main product. Dry over anhydrous potassium carbonate and distil. Collect the diethylnitrosamine at 172-173-5°, The yield is 41 g. 

Inhibition of Nitrosamine Formation. Nitrites can react with secondary amines and A/-substituted amides under the acidic conditions of the stomach to form /V-nitrosamines and A/-nitrosamides. These compounds are collectively called N-nitroso compounds. There is strong circumstantial evidence that in vivo A/-nitroso compounds production contributes to the etiology of cancer of the stomach (135,136), esophagus (136,137), and nasopharynx (136,138). Ascorbic acid consumption is negatively correlated with the incidence of these cancers, due to ascorbic acid inhibition of in vivo A/-nitroso compound formation (139). The concentration of A/-nitroso compounds formed in the stomach depends on the nitrate and nitrite intake. 

Synthesis. Almost without exception, azo dyes ate made by diazotization of a primary aromatic amine followed by coupling of the resultant diazonium salt with an electron-rich nucleophile. The diazotization reaction is carried out by treating the primary aromatic amine with nitrous acid, normally generated in situ with hydrochloric acid and sodium nitrite. The nitrous acid nitrosates the amine to generate the N-nitroso compound, which tautomerizes to the diazo hydroxide. 

Attempted diazotization in dilute acid sometimes yields primary nitroso compounds. Reactions of 3- and 5-amino-1,2,4-thiadiazoles with sodium nitrite and acid give primary nitrosamines (e.g. 432->433) (65AHC(5)n9) which can be related to the secondary nitrosamines (434) prepared in the normal way. 1-Substituted 5-aminotetrazoles with nitrous acid give stable primary nitrosamines (435). Primary nitrosamines have been isolated in the imidazole series. 

Electrophilic nitrosation of the carbanion generated from the reaction of an organic base with a strong organic acid, such as a-hydrohexafluoroisobutyronitnle [2], a hydrohexafluoroisobutyric acid or its acid chloride [2], or a hydrotetra fluoroethanesulfonyl fluoride [4], yields the corresponding a-nitroso compound as the major product (equations 2 and 3) The a-hydrohexafluoroisobutyric acid or acid chloride reacts with excess trifluoroacetyl nitrite in dimethylformamide to afford the O substituted oxime [3] (equation 4)... 

Camphene forms a well-defined nitrite, and a nitroso-nitrite, when treated in the following manner A well-cooled solution of camphene in petroleum ether is mixed with a saturated solution of sodium nitrite, and dilute acetic acid is added. The mixture is well stirred, being kept cool all the time. Camphene nitrosonitrite, CuHi NjOj, separates and on recrystallisation forms crystals which decompose at about 149°. The petroleum ether solution, which has been filtered off from this compound, is shaken with a concentrated solution of pK)tassium hydroxide, which removes camphene nitrosite, CjQHigNjOj, in the form of its potassium salt. When this is decomposed with acids it yields the free nitrosite. This compound is a greenish oil, with a pleasant odour, easily decomposing when heated to 50°. 

Carbons adjacent to a Z group (as defined on p. 548) can be nitrosated with nitrous acid or alkyl nitrites. The initial product is the C-nitroso compound, but these are stable only when there is no tautomerizable hydrogen. When there is, the product is the more stable oxime. The situation is analogous to that with azo compounds and hydrazones (12-7). The mechanism is similar to that in 12-7 R—H —> R + N=0 — R—N=0. The attacking species is either NO or a carrier of it. When the substrate is a simple ketone, the mechanism goes through the enol (as in halogenation 12-4) ... 

Other compounds with nitrogen-nitrogen bonds have been used instead of diazonium salts. Among these are N-nitroso amides [ArN(NO)COR], triazenes, and azo compounds. Still another method involves treatment of an aromatic primary amine directly with an alkyl nitrite in an aromatic substrate as solvent. ... 

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