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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Acceleration and Reaction Mechanism of the N-Nitrosation Reaction of Dimethylamine with Nitrite in Ice
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Acceleration and Reaction Mechanism of the N-Nitrosation Reaction of Dimethylamine with Nitrite in Ice

机译：二甲胺与冰中二甲胺的N-硝酸化反应的加速度与反应机理

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Some reactions (e.g., oxidation of nitrite, denitrification of ammonium) are accelerated in freeze-concentrated solution (FCS) compared to those in aqueous solution. Ice is highly intolerant to impurities, and the ice excludes those that would accelerate reactions. Here we show the acceleration of the N-nitrosation reaction of dimethylamine (DMA) with nitrite to produce N-nitrosodimethylamine (NDMA) in FCS. NDMA is a carcinogenic compound, and this reaction is potentially accelerated in frozen fish/meat. The eaction rate of the N-nitrosation reaction becomes fastest at specific pH. This means that it is a third-order reaction. Theoretical pH values of the peak in the third-order reaction are higher than the experimental one. Freeze-concentration of acidic solution causes pH decrement; however, the freeze-concentration alone could not explain the difference of pH values. The theoretical value was obtained under the assumption that no solute took part in ice. However, solutes are incorporated in ice with a small distribution coefficient of solutes into ice. This small incorporation enhanced the decrement of pH values. Using the distribution coefficient of chloride and sodium ion and assuming those of nitrite and DMA to explain the enhancement, we succeeded in estimating the distribution coefficients of nitrite: 2 x 10(-3) and DMA: 3 x 10(-2).
机译：与水溶液中的那些相比，一些反应（例如，亚硝酸盐的氧化，铵的反硝化，铵）加速了在冷冻浓缩的溶液（Fcs）中加速。冰对杂质具有高度不耐受性，并且冰块不包括将加速反应的冰。在这里，我们展示了二甲胺（DMA）与亚硝酸盐的N-硝化反应的加速，从而在FCS中产生N-硝基二甲基甲胺（NDMA）。 NDMA是一种致癌化合物，并且该反应可能加速冷冻鱼/肉。 N-硝化反应的注射率在特定pH下变得最快。这意味着它是三阶反应。三阶反应中峰的理论pH值高于实验性。酸性溶液的冷冻浓度导致pH递减;然而，单独的冷冻浓度无法解释pH值的差异。在假设中获得理论价值，即没有溶质在冰中占据冰。然而，溶质掺入冰中，溶质的小分布系数溶于冰中。这个小的掺入增强了pH值的减少。使用氯化物和钠离子分布系数并假设亚硝酸盐和DMA的分配系数来解释增强，我们估计亚硝酸盐的分布系数：2×10（-3）和DMA：3×10（-2）。

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