TEA法测定NO_2的反应机理研究

Reaction Mechanism of NO_2 Determination by the TEA Method

应用 FABMS、 NMR、 IR、 HPL C和紫外吸收光谱研究了室温下三乙醇胺与较高浓度 NO2(2 .4 8% )的反应情况 ,证明反应产物为三乙醇胺硝酸盐和三乙醇胺亚硝酸盐 ,提出了可能的反应机理 ,为 TEA法监测空气中 NO2 的浓度提供了依据 .

The reaction of triethanolamine(TEA) with NO 2 was investigated at room temperature. The reaction products were characterized by FABMS, NMR, FTIR, HPLC and UV spectra. It was found that triethanolamine nitrate and triethanolamine nitrite are the main products of the reaction. (HOC 2H 4) 3NH + was identified based on FABMS, 1H NMR, and 13 C NMR spectra. Meanwhile, NO - 3 and NO - 2 were also determined by FTIR, HPLC and UV spectra. The quantitative relationship between TEA and NO 2 that infolved in the reaction was determined by experiments. It was found that when TEA was reacted with NO 2 in CHCl 3 with the exclusion of water, a white precipitate formed immediately on addition of NO 2, this precipitate could solve easily in strong polarized solvents such as water. Triethanolamine nitrate was obtained through TEA reacted with HNO 3 in CHCl 3 at room temperature, moreover the comparison of its spectra and the ones of the products was made. A possible reaction mechanism was proposed to explain the experimental results. Because N 2O 4 molecule is electron deficient while TEA contains atoms which have one or more lone pairs of electrons available in s or p orbitals, a molecular addition compound might be the reactive intermediate, which can easily be hydrolyzed to give the final products. This reaction mechanism requires a stoichiometric factor of 0.5 for the conversion of gaseous NO 2 to nitrite ion, which is in agreement with literature values.