Ohshima H, Kawabata T
IARC Sci Publ (1971). 1978(19):143-53.
The kinetics of nitrosation of trimethylamine (TMA) and trimethylaminoxide (TMAO) to give N-nitrosodimethylamine (NDMA) have been studied. The nitrosation rates of TMA and TMAO, when determined at 100 degrees C in sealed tubes, showed maximum values at about pH 3, while at temperatures lower than 75 degrees C the pH dependence of the nitrosation of these compounds was similar to that observed with alkylamides. The initial rate of NDMA formation from TMAO determined at pH 3.0 and 25 degrees C was found to be proportional to the TMAO and nitrite concentrations, not to the square of the nitrite concentration. In contrast, the rates of NDMA formation from TMA and TMAO when reacted at pH 3.0 and 100 degrees C in sealed tubes were found to be proportional to the square and the cube, respectively, of the nitrite concentration. These results strongly suggest that the NDMA formation at higher temperatures involves the oxidative cleavage of tertiary amines to produce secondary amines (dimethylamine, DMA) which may react with nitrite to form NDMA. On the other hand, at lower temperatures, NDMA may be formed from TMA or TMAO by a pathway not involving DMA.
研究了三甲胺（TMA）和三甲胺氧化物（TMAO）亚硝化生成N-亚硝基二甲胺（NDMA）的动力学。在密封管中于100℃测定时，TMA和TMAO的亚硝化速率在pH约为3时显示出最大值，而在低于75℃的温度下，这些化合物亚硝化的pH依赖性与烷基酰胺的情况相似。在pH 3.0和25℃下测定的由TMAO生成NDMA的初始速率与TMAO和亚硝酸盐浓度成正比，而非与亚硝酸盐浓度的平方成正比。相比之下，当在密封管中于pH 3.0和100℃反应时，由TMA和TMAO生成NDMA的速率分别与亚硝酸盐浓度的平方和立方成正比。这些结果有力地表明，在较高温度下NDMA的形成涉及叔胺的氧化裂解以产生仲胺（二甲胺，DMA），其可能与亚硝酸盐反应形成NDMA。另一方面，在较低温度下，NDMA可能通过不涉及DMA的途径由TMA或TMAO形成。
