Formation of nitrosamines in organic solvents and aqueous systems containing organic solvents

Article abstract of DOI:10.1248/cpb.33.2516

Formation of N-nitrosodimethylamine and N-nitrosodiethylamine in organic solvents such as chloroform, benzene, ethyl acetate, n-hexane, acetonitrile and dioxane was much faster than that in the control citrate buffer at pH 3. This effect of the organic solvents may be due to their ability to suppress ionization of nitrous acid. Formation of the nitrosamines in acetone was faster, but the yield was less than in other organic solvents, probably due to reaction of the solvent with nitrous acid. Ethyl alcohol was not useful as the control buffer, since it consumed nitrous acid to produce nitrite ester. The use of pH-controlled aqueous systems containing acetonitrile and dioxane accelerated the formation of the nitrosamines by increasing the concentration of nitrous acid; the 25% acetonitrile-containing system produced 3 times as much N-nitrosodimethylamine and 6 times as much N-nitrosodiethylamine as compared to the control citrate buffer at pH 4. Formation of the nitrosamines in citrate was accelerated or inhibited by addition of acetone and ethyl alcohol depending upon the pH conditions. It is concluded that most organic solvents suppressed the ionization of nitrous acid and accelerated the nitrosation of the secondary amines.

Full text of DOI:10.1248/cpb.33.2516

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