Ester-mediated nitrosamine formation from nitrite and secondary or tertiary amines

N-Nitrosamines are formed from the heating of either a secondary or a tertiary amine with sodium nitrite in the presence of a high-boiling ester such as 2-acetoxyethanol in ethylene glycol. The four secondary and six tertiary amines examined were found to produce N-nitrosamines in yields ranging from 4% to 80% when equimolar amounts of amine and ester were heated at 120 degrees C with one- to ten-fold equivalents of sodium nitrite in ethylene glycol. Secondary amines competitively produced acetamides at a rate slightly greater than N-nitrosamine formation. Preincubation of a large excess of sodium nitrite and ester led to the rapid formation of N-nitrosamines in high yield. The reaction of tribenzylamine resulted in the formation of both benzaldehyde and dibenzylnitrosamine. N,N-Dimethylbenzylamine reacted to give nearly equimolar amounts of N-nitrosodimethylamine and N-nitroso-N-methylbenzylamine. It is proposed that the nitrosating agent is a nitrous ester, and it is shown that 2-benzoxyethyl nitrite rapidly nitrosates secondary and tertiary amines under these reaction conditions. It is also proposed that these transformations are good models for the environmental formation of N-nitrosamines in foods and commercial products.