García-Río Luis, Hervella Pablo
Departamento de Química Física, Facultad de Química, Universidad de Santiago, 15782 Santiago, Spain.
Chemistry. 2006 Nov 6;12(32):8284-95. doi: 10.1002/chem.200600091.
A study was carried out on the nitrosation of piperazine (PIP) and N-methylbenzylamine (MeBzAm) by N-methyl-N-nitroso-p-toluenesulfonamide (MNTS) in quaternary microemulsions of tetradecyltrimethylammonium bromide (TTABr)/isooctane/alcohol/water, varying the nature and the concentration of the following alcohols: 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol and 1-decanol keeping the [1-alcohol]/[TTABr] = 4 relationship constant. In addition a study was carried out on the influence of the alcohol concentration, working with molar relationships [1-hexanol]/[TTABr]=3, 4 and 5. On the basis of the molar volumes of the alcohol and surfactant and the concentration of alcohol at the interface it was possible to calculate the change in its volume with as varying compositions of the microemulsion. In order to interpret the experimental results a kinetic model was devised which takes into account the distribution of the reactants between the different pseudophases and the change in the volume of the interface. The rate constants at the interface of the microemulsion are lower than in pure water and are independent of the nature of the alcohol used as a cosurfactant and the molar relationship [alcohol]/[TTABr]. This independence indicates that the main role of the cosurfactant is to increase the volume of the interface with the consequent dilution of the reactants.
以十四烷基三甲基溴化铵（TTABr）/异辛烷/醇/水的季铵微乳液为体系，采用N - 甲基 - N - 亚硝基对甲苯磺酰胺（MNTS）对哌嗪（PIP）和N - 甲基苄胺（MeBzAm）进行亚硝化研究，改变以下醇类的性质和浓度：1 - 戊醇、1 - 己醇、1 - 庚醇、1 - 辛醇和1 - 癸醇，保持[1 - 醇]/[TTABr] = 4的关系恒定。此外，研究了醇浓度的影响，采用的摩尔比为[1 - 己醇]/[TTABr] = 3、4和5。根据醇和表面活性剂的摩尔体积以及界面处醇的浓度，可以计算出随着微乳液组成变化其体积的变化。为了解释实验结果，设计了一个动力学模型，该模型考虑了反应物在不同假相之间的分布以及界面体积的变化。微乳液界面处的速率常数低于纯水中的速率常数，且与用作助表面活性剂的醇的性质以及[醇]/[TTABr]的摩尔比无关。这种独立性表明助表面活性剂的主要作用是增加界面体积，从而使反应物稀释。
