Nitrites, listing

The scientific and technical corrosion literature has descriptions and lists of numerous chemical compounds that exhibit inhibiting properties. Of these only a very few are ever actually used in practical systems. This is partly due to the fact that in practice the desirable properties of an inhibitor usually extend beyond those simply relating to metal protection. Thus cost, toxicity, availability, etc. are of considerable importance as well as other more technical aspects (see Principles). Also, as in many other fields of scientific development, there is often a considerable time lag between laboratory development and practical application. In the field of inhibition the most notable example of this gap between discovery and application is the case of sodium nitrite. Originally reported in 1899 to have inhibitive properties, it remained effectively unnoticed until the 1940s it is now one of the most widely employed inhibitors. 

The reaction of alkyl halides with metal nitrites is one of the most important methods for the preparation of nitroalkanes. As a metal nitrite, silver nitrite (Victor-Meyer reaction), potassium nitrite, or sodium nitrite (Kornblum reaction) have been frequently used. The products are usually a mixture of nitroalkanes and alkyl nitrites, which are readily separated by distillation (Eq. 2.47). The synthesis of nitro compounds by this process is well documented in the reviews, and some typical cases are listed in Table 2.3.92a Primary and secondary alkyl iodides and bromides as well as sulfonate esters give the corresponding nitro compounds in 50-70% yields on treatment with NaN02 in DMF or DMSO. Some of them are described precisely in vol 4 of Organic Synthesis. For example, 1,4-dinitrobutane is prepared in 41 -46% yield by the reaction of 1,4-diiodobutane with silver nitrite in diethyl ether.92b 1-Nitrooctane is prepared by the reaction with silver nitrite in 75-80% yield. The reaction of silver nitrite with secondary halides gives yields of nitroalkanes of about 15%, whereas with tertiary halides the yields are 0-5%.92c Ethyl a-nitrobutyrate is prepared by the reaction of ethyl a-bromobutyrate in 68-75% yield with sodium nitrite in DMF.92d Sodium nitrite is considerably more soluble in DMSO than in DMF as a consequence, with DMSO, much more concentrated solutions can be employed and this makes shorter reaction times possible.926... 

Annex III lays down the conditions of use for permitted preservatives and antioxidants, with lists of foods and maximum levels in each case. Part A lists the sorbates, benzoates and p-hydroxybenzoates, E 200-E 219 part B lists sulphur dioxide and the sulphites, E 220-E 228 part C lists other preservatives with their uses, including nisin, dimethyl dicarbonate and substances allowed for surface treatment of certain fruits, E 249 potassium nitrite, E 250 sodium nitrite, E 251 sodium nitrate and E 252 potassium nitrate, E 280-E 283 propionic acid and the propionates part D lists the antioxidants E 320 butylated hydroxyanisole (BHA), E 321 butylated hydroxytoluene (BHT), E 310 propyl gallate, E 311 octyl gallate, E 312 dodecyl gallate, E 315 eiythorbic acid and E 316 sodium erythorbate. 

TPD of Cu-Al-MCM-41 (after NO adsorption under 0.8% NO in He) was eondueted (Table 14). NO and NO2 are the species detected coming off the surface as the temperature of the catalyst is increased. Two features were observed in the NO desorption profile a principal peak at 149 °C and a second NO desorption feature at higher temperature (440 °C). This indicates that there are at least two types of NO adsorption sites available. The presence of two types of adsorbed NO species over Cu catalysts has been reported earlier in the literature[45]. These have been proposed to be the desorption of NO from Cu ions and nitrate (NO3 ), nitrite (NO2 ) or N02 adsorbed species, respectively. Assuming the sensitivity factors of the peaks at low and high temperature are equivalent, the areas can be used to estimate the normalized desorption of NO. As listed in Table 14, the amount of NO desorbed at low temperature is close to the total amoimt of desorbed NO. This feature indicates that copper is mainly as isolated Cu in the catalyst. During NO desorption, a small amoimt of NO2 (8.2 pmol/g) desorbed at 80 °C. 

In Table 1 is a list of the environmental secondary and tertiary amines which have been tested by feeding to rats together with nitrite. Of these, several react very readily with nitrite in acid solution, but some, for example phenmetrazine (2 , 27), give rise to a noncarcinogenic N-nitroso derivative. On the other hand, aminopyrine reacts extremely readily with nitrous acid, although it is a tertiary amine, and forms the potent carcinogen nitrosodimethylamine in high yield (28, ). The other amines vary considerably in the extent to which they form N-nitroso derivatives by reaction with nitrous acid, especially at the relatively low concentrations which model human exposure more closely... 

Other, more sensitive, tests have been suggested for the evaluation of potential carcinogenic risk of exposure to chemicals. These include the bacterial mutagenesis test devised by Dr. Bruce Ames ( ). This test has been applied to many of the amines listed in Table 1, both alone and after reaction with nitrite in weakly acid solution, followed by neutralization and application to the bacteria. In Table 3 are given the results of a number of such tests, together with comparison of the results of chronic... 

Little Inc Rept (Ref 6, pp 81, 107 108), the prepn of the Potassium salt is described using Ter Meet s method, as modified by Jacobson (Ref 4). For this, to 1-cbloro-l-nitroethane (listed in Vol 3 of our Encycl, p C254-R) dissolved in methanol, was added at about 0° an aq soln of K nitrite. A short... 

N.V. Chalov L.P. VoTskaya, Zavodskaya-Lab 12, 286-91 (1946) CA 4l, 3399-4000 (1947) (Detn of ethanol in dilute aqueous solns by a method, which is modification of the method of Fischer Schmidt, listed here as Ref 2. Both methods are based on the conversion of alcohol to its nitrite and total time required is 20 mins. Sensitivity is as low as 0.025—0.005% and accuracy i 3%. A fairly detailed description of the method is given in the above CA)... 

Another method of prepn listed in AMCP 706—177 is from ami no guanidine sulfate and Na nitrite in distd w... 

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. 

Phloroglucinol is listed in the Colourlndex as Cl Developer 19. It is particularly valuable in the dyeing of acetate fiber but also has been used as a coupler for azoic colors in viscose, Orion, cotton (qv), rayon, or nylon fibers, or in union fabrics containing these fibers (157). For example, cellulose acetate fabric is treated with an aromatic amine such as 0-dianisidine or a disperse dye such as hydroxyphenylazo-2-naphthylamine and the amine diazotizes on the fiber the fabric is then rinsed, freed of excess nitrite, and the azo color is developed in a phloroglucinol bath at pH 5—7. Depending on the diazo precursor used, intense blue to jet-black shades can be obtained with excellent light-, bleach-, and rubfastness. 

Diazo transfer reactions p-Toluenesulfonyl azide, 226 Diazotization Sodium nitrite, 170, 282 Dicarboxylation (see Addition reactions to carbon-carbon multiple bonds) Diels-Alder reaction (For a list of dienes and dienophiles see Type of Compound Index)... 

The nitro group does not undergo migration of the naphthalene ring during the usual nitration procedures. Therefore, mono- and polynitration of naphthalene is similar to low temperature sulfonation, The nitronaphthalenes and some of their physical properties arc listed in fable 2. Many of these compounds are not accessible by direct nitration of naphthalene but are made by indirect methods, e.g nitrite displacement of diazonium halide groups in the presence of a copper catalysts, decarboxylation of nitronaphtbalcnccar-boxylic acids, or deamination of nitronaphthalene amines. They are nsed in the manufacture of chemicals, dye intermediates, and colorants for plastics. 

Cobalt Nitrites,Cobaltous Nitrite, Co(NOz)2, red crysts, mp-decomp on slight heating was first prepd in 1848 (Ref 1) on treating an aqueous suspension of Co pdr with Ag nitrite soln. Several other methods of prepn are listed in Ref 2. There are also known basic cobaltic nitrite and basic cobalto-cobaltic nitrite (Ref 2), but no cobaltic salt, Co(N02)3... 

When nitrites and nitrates are thermally decomposed, nitrogen, oxygen, and their compounds are produced. A literature survey produces the following list of substances which appear in one or another decomposition 02, N2, NO, N02, N203, N204, N205. Which of these compounds are produced in any specific case depends on the salt, temperature, and experimental conditions. Since reactions between these compounds occur quite readily, thermodynamic functions for them have been listed (Tables 5.1 to 5.8). The matter of reactions between all these compounds is somewhat complicated, because several of them are thermodynamically quite unfavorable and thus do not need to be considered. On that basis the following conclusions can be drawn ... 

The coordination of the nitrite ion appears to differ with the salt. For example, in AgN03, Ag+ is closer to N than to O, whereas in NaN02, Na+ is closer to O than to N.2 The periodic table existence chart (Figure 5.1) which lists the known nitrites omits bonding information. 

When oxides of nitrogen come in contact with water, both nitrous and nitric acids are formed (18) (Table IV). Toxic reactions may result from pH decrease. Other toxic reactions may be a consequence of deamination reactions with amino acids and nucleic acid bases. Another consideration is the reactions of oxides of nitrogen with double bonds (Table IV). The cis-trans isomerization of oleic acid exposed to nitrous acid has been reported (19). Furthermore, the reaction of nitrogen dioxide with unsaturated compounds has resulted in the formation of both transient and stable free radical products (20, 21) (Table V). A further possibility has been raised in that nitrite can react with secondary amines to form nitrosamines which have carcinogenic properties (22). Thus, the possible modes of toxicity for oxides of nitrogen are numerous and are not exhausted by this short list. 

Table 5 contains the gas-phase activation parameters for syru- anti conformational exchange available for six primary alkyl nitrites. Two trends are apparent in the gas-phase activation parameters listed in this table. First, the barrier to sync anti... 

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