Nitrite alternatives

Concern about the potential injurious effects of nitrite in the diet have motivated study of alternatives to this multi-purpose food additive. The significance for human health of nitrate, nitrite and N-nitroso compounds has been reviewed by Mirvish (1991). The occurrence of these substances in food and in the diet and the toxicological implications were reviewed by Walker (1990). 

The aspect that has caused most concern with regard to nitrate and nitrite in foods is the formation of N-nitrosamines in some cured products, either formed during processing or in the stomach (Bogovski and Bogov-ski, 1991). 

Developing alternatives to nitrite is extremely difficult because of its many functions in food including its antimicrobial effect against C. botuli-num, its role in the formation of the characteristic colour of cured meats, its antioxidant activity that prevents the formation of off-flavours and its contribution to the characteristic flavour and texture of cured meats. 

When low levels of nitrite are used in curing meat, most if not all of the nitrite is in the bound form and is thus unavailable as an antimicrobial. Currently about 120 mg/kg sodium nitrite is typically used in cured products to ensure anti-botulinal activity, whereas less than 40 mg/kg is actually required for colour and flavour development. 

The flavour of cooked meat is due in part to oxidation products. In cured meats, nitrite acts as an antioxidant and inhibits the formation of 

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Pierson, M. D., and Smoot, L. A. (1982). Nitrate, nitrite alternatives, and the control of Clostridium botulinum in cured meats. Grit. Rev. Food Sci. Nutr. 17, 141-187. 

Platinum is generally introduced as dinitrodiammineplatinum(II), [Pt(NH3)2(N02)2] the solution also contains ammonium nitrate and sodium nitrite. Alternatively, H2PtCl6 or Na2[Pt(OH)6], both derivatives of platinum(IV), have been used. 

In our search for nitrite alternatives, as far as flavor and oxidative stability Is concerned, we examined the effect of commonly used adjuncts In meat curing, as well as a large ntimber of antloxldant/sequesterant systems (40-42). In particular, the effect of sodium ascorbate (SA) and sodium tripolyphosphate (STFF) on the oxidative state of cooked meats was studied. These additives lowered the TEA numbers by a factor of about 2 and 4, respectively (Table IV). When used In combination, a strong synergism was observed. Furthermore, an Increase In the concentration of SA and/or STFF resulted In a decrease In the TEA values as depicted In Figure 6 (43). Addition of 30 ppm of butylated hydroxyanlsole (EHA) or tert-butylhydroqulnone (TEHQ) further reduced the TEA numbers and In fact the latter values were even lower than those obtained for meats treated with sodium nitrite (Table IV) (41). 

Nitrite alternatively may be determined via the diazotization with sulfanilic acid followed by the coupling with N-(l-naphthyl)ethylenediamine dihydrochloride, detection limits being 10 moll . Possible enhancement of the sensitivity could be achieved by adsorptive cathodic stripping of this complex. 

Pegg, R. B. and F. Shahidi. 2000. Nitrite Curing of Meat. The N-Nitrosamine Problem and Nitrite Alternatives. Trumbull, CT Food and Nutrition Press Inc. 

In preparing an aqueous sol ution of a diazonium salt, such as benzene-diazonium chloride, it is usual to dissolve the amine in a slight excess (about 2 2 molecular equivalents) of dilute hydrochloric acid (or alternatively to dissolve the crystalline amine hydrochloride in i 2 equivalents of the acid) and then add an aqueous solution of a metallic nitrite. Nitrous acid is thus generated in situ, and reacts with the amine salt to give the diazonium compound. For a successful preparation of an aqueous solution of the diazonium salt, however, two conditions must always be observed ... 

I) An alternative procedure is to cool the solution containing the sodium sul. phanilate and sodium nitrite in a bath of crushed ice to about 5° and then add 10-5 ml. of concentrated hydrochloric acid diluted with an equal volume of water slowly and with stirring the temperature must not be allowed to rise above 10 and an excess of nitrous acid should be present (the solution is tested after standing for 5 minutes). The subsequent stages in the preparation—addition of dimethyl-aniline solution, etc.—are as above. 

An alternative method of removing the aniline is to add 30 ml. of concentrated sulphuric acid carefully to the steam distillate, cool the solution to 0-5°, and add a concentrated solution of sodium nitrite until a drop of the reaction mixture colours potassium iodide - starch paper a deep blue instantly. As the diazotisation approaches completion, the reaction becomes slow it will therefore be necessary to teat for excess of nitrous acid after an interval of 5 minutes, stirring all the whUe. About 12 g. of sodium nitrite are usually required. The diazotised solution is then heated on a boiling water bath for an hour (or until active evolution of nitrogen ceases), treated with a solution of 60 g. of sodium hydroxide in 200 ml. of water, the mixture steam-distilled, and the quinoline isolated from the distillate by extrsM-tion with ether as above. 

An alternative procedure involves use of alkyl nitrites and traps the desired product as an acetal[16],... 

III.2.C). The deamination of 2-aminothiazoles could be performed alternatively by refluxing them with amyl nitrite in tetrahydrofuran (604),... 

None of the atoms in the Lewis structure shown in step 6 possesses a formal charge An alternative Lewis structure for methyl nitrite... 

Plutonium Purification. The aqueous feed for the second plutonium cycle is typically prepared by adding HNO and an excess of sodium nitrite, NaN02, to destroy the excess reductant and oxidize the Pu to the more extractable Pu . An alternative approach which reduces the amount of salt in the Hquid waste involves absorbing nitrogen tetroxide, N2O4, as a substitute for the NaN02 ... 

The need for low levels of 3-isomer in 2-thiophenecarboxyhc acid [527-72-0] which is produced by oxidation of 2-acetylthiophene [88-15-3] and used in dmg appHcations, has been the driving force to find improved acylation catalysts. The most widely used oxidant is sodium hypochlorite, which produces a quantity of chloroform as by-product, a consequence that detracts from its simplicity. Separation of the phases and acidification of the aqueous phase precipitate the product which is filtered off. Alternative oxidants have included sodium nitrite in acid solution, which has some advantages, but, like the hypochlorite method, also involves very dilute solutions and low throughput volumes. 

Cl Vat Blue 4 is prepared from 2-arniaoaiitliraquiQoiie (66) by potash fusion in the presence of an oxidising agent such as sodium nitrite or air. An alternative method by dimerization of 1-aminoanthraquinone (17) by using such solvents as dimethyl sulfoxide or tetramethylurea has been reported, and improved methods for this reaction have been cited (135—138). These methods are considered to be advantageous in terms of the yield as well as the availability of starting compounds. 

Avoid the use of water-mix synthetic fluids containing nitrites if there is a technologically effective alternative. 

The immediate outcome of the Hantzsch synthesis is the dihydropyridine which requires a subsequent oxidation step to generate the pyridine core. Classically, this has been accomplished with nitric acid. Alternative reagents include oxygen, sodium nitrite, ferric nitrate/cupric nitrate, bromine/sodium acetate, chromium trioxide, sulfur, potassium permanganate, chloranil, DDQ, Pd/C and DBU. More recently, ceric ammonium nitrate (CAN) has been found to be an efficient reagent to carry out this transformation. When 100 was treated with 2 equivalents of CAN in aqueous acetone, the reaction to 101 was complete in 10 minutes at room temperature and in excellent yield. 

In an alternative route described in U.S. Patent 3,028,429 propiophenone may be reacted with an alkyl nitrite to give isonitrosopropiophenone which is then hydrogenated and finally converted to the hydrochloride. 

Where molybdate/nitrite programs are employed in LP steam and higher temperature HW heating systems, they typically require 250 to 350 ppm as Mo04 and the same level of N02. Alternatives reduce the molybdate level to perhaps 150 to 250 ppm and increase the nitrite level to 500 to 600 ppm. Where molybdate/silicate programs are used, the silica level is again, about one-third of the molybdate level. 

The diazotization reaction can also be initiated via the vapor phase, e. g. with ethyl nitrite that can be generated in one trough of a twin-trough chamber by adding a few drops of cone, hydrochloric acid to a mixture of ethanol and saturated aqueous sodium nitrite solution (1 + 1) [3] the less volatile amyl nitrite can be used as an alternative [3]. 

The ferrocene moiety is not just an innocent steric element to create a three-dimensional chiral catalyst environment. Instead, the Fe center can influence a catalytic asymmetric process by electronic interaction with the catalytic site, if the latter is directly coimected to the sandwich core. This interaction is often comparable to the stabilization of a-ferrocenylcarbocations 3 (see Sect. 1) making use of the electron-donating character of the Cp2Fe moiety, but can also be reversed by the formation of feirocenium systems thereby increasing the acidity of a directly attached Lewis acid. Alternative applications in asymmetric catalysis, for which the interaction of the Fe center and the catalytic center is less distinct, have recently been summarized in excellent extensive reviews and are outside the scope of this chapter [48, 49], Moreover, related complexes in which one Cp ring has been replaced with an ri -arene ligand, and which have, for example, been utilized as catalysts for nitrate or nitrite reduction in water [50], are not covered in this chapter. 

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