环己烷氧化副产物全组分的质谱分析

Study of By-product from Cyclohexane Oxidation by Multiple Mass Spectrometry Technologies

本研究建立了利用多种质谱技术分析表征环己烷氧化副产物的方法。将环己烷氧化副产物在减压条件下切割为馏程小于300℃的轻组分与馏程大于300℃的重组分。利用全二维气相色谱-飞行时间质谱法（GC×GC-TOF MS）对轻组分中的54种含氧有机物进行定性与半定量分析,发现轻组分主要是由酮类、醚类与醇类组成。利用傅立叶变换-离子回旋共振质谱法（FT-ICR MS）对重组分的分子组成进行表征,发现重组分中基本是O2O5类的含氧有机物。重组分中化合物的碳数随O原子个数的增加而增加,但双键相等数（DBE）的分布却基本不变,从而推测重组分中可能同时含有环烷环、C=C、C≡O以及醇、醚类C—O键等多种官能团。利用傅里叶变换红外光谱（FTIR）技术验证了质谱分析结果的可靠性。本工作可为含氧有机物混合复杂体系的分析研究提供新的思路。

A method for analyzing by-product from cyclohexane oxidation by multiple mass spectrometry technologies was established.The by-product was distilled to light fraction（distillation range〈300℃）and heavy fraction（distillation range〉300℃）by vacuum distillation.The qualitative and quasi-quantitative analysis for the light fraction of the by-product were carried out by comprehensive two-dimensional gas chromatography-time of fight mass spectrometry（GC×GC-TOF MS）.54 kinds of oxygen compounds,which composed of ketones,ethers,alcohols,esters,aldehydes,phenols and hydrocarbons are identified.The carbon number distribution of the light fraction is5-1 4.The compounds,with the carbon number of 1 2,account for more than 7 0%of the light fraction.As the carbon number of 2-cyclohexylidene-cyclohexanone,2-（1-cyclohexenyl）cyclohexanone and oxydicyclohexane,which are the major com-pounds of the light fraction,were all 12.The compounds with the carbon number of6 have the second highest content.The composition of the heavy fraction is more complex than the light fraction.It was characterized by Fourier transform-ion cyclotron resonance mass spectrometry（FT-ICR MS）.The main components of the heavy fraction are O2-O5 compounds.The carbon number distribution of these oxygen compounds range widely,which are from 10 to 40.The compounds with the carbon number of 18 and 24have higher content.The fact that compounds with multiples of 6carbon atoms have higher content both in light and heavy fraction,illustrates that the structure of cyclohexane is reserved during the oxidation procedure.As for the compounds in the heavy fraction,their carbon numbers increase with the rising of oxygen numbers,while the distribution of double bond equivalents（DBE）remains the same.The structures of hexatomic ring,C=C,C≡O and C—O of alcohols or ethers were predicted in the heavy fraction,which was verified by Fourier transform infrared spectroscopy（FTIR）.The detailed composition information is helpful for the reproduction and reprocessing of the by-product from cyclohexane oxidation.It can provide a new method for analyzing and researching of the complex system containing oxygen compounds.