In nitrosation

It is appropriate to add here some comments on diazotization in anhydrous carboxylic acids. They may be relevant for the diazotization of heteroaromatic amines carried out in acetic acid/propionic acid mixtures (Sec. 2.2). Extensive studies by Casado et al. (1983, 1984) showed that in nitrosation of secondary amines the nitrosyl ion, nitrosyl acetate, and dinitrogen trioxide are formed, and all three may act as nitrosating agents. The results do not, however, account for the considerable improvement that is claimed in the patent literature (Weaver and Shuttleworth, 1982) to result from the addition of carboxylic acids in the diazotization of heteroaromatic amines. 

A research program in progress at Raltech Scientific Services is designed to find inhibitors which will prevent nitrosamine formation in cosmetic products, A review of the literature (4) indicated that the oil phase of emulsions may play an important role in nitrosation chemistry. Thus, results from studies in water alone could be misleading when reduced to practice. 

Only a few studies have been undertaken on the role of bacteria in nitrosation at neutral pH in the Intestinal tract itself. Hashimoto al. (9 ) demonstrated that by changing the equilibrium between different species of microorganisms in the gut, (by administration of antibiotics and inoculation with nitrate-reducing strains) dimethylnitrosamine (NDMA) accumulated in the stomach and cecum of rats fed dlmethylamine (DMA) and nitrate. The authors describe only one experimental group, however, and the mechanism of NDMA formation is not clear. 

Diffusion control and pre-association in nitrosation, nitration, and halogenation, 16,1... 

N02 probably plays a more important role in nitrosating reactions in biological systems than proposed earlier. Thus Espey et al. [94] suggested that the oxidation of NO into N203 with the intermediate formation of N02 could be more important in cells compared to aqueous solution. Furthermore, N02 is a likely candidate in oxidative processes due to its ability to penetrate cells [95],... 

Williams DLH (1988) In Nitrosation. Cambridge University Press, New York... 

Common electron acceptors that will participate in nitrosating reactions include nitrogen dioxide, transition metals, and possibly oxygen. For example, nitric ox-... 

Calmels, S., Ohshima, H., and Bartsch, H. (1988). Nitrosamine formation by denitrifying and non-denitryfying bacteria Implications of nitrite reductase and nitrate reductase in nitrosation catalysis. . Gen. Microbiol. 134, 221-226. 

Diffusion control and pre-association in nitrosation, nitration, and halogenation, 16, 1 Dimethyl sulphoxide, physical organic chemistry of reactions, in, 14, 133 Diolefin crystals, photodimerization and photopolymerization of, 30, 117 Dipolar aptotic and protic solvents, rates of bimolecular substitution reactions in,... 

Diffusion Control and Pre-association in Nitrosation, Nitration and Halogenation... 

---