在线热裂解/气相色谱-质谱分析3-吡啶甲酸茴香酯的热裂解产物

Analysis of Pyrolysates from 3-Pyridine Formic Acid Anisalcohol Ester by On-line Pyrolysis/Gas Chromatography- Mass Spectrometry

采用在线热裂解/气相色谱-质谱（Py/GC-MS）联用技术对3-吡啶甲酸茴香酯进行热裂解分析。通过酰氯化和酯化反应合成了新型目标化合物3-吡啶甲酸茴香酯,其分子式为C14H14NO3。目标化合物的结构经核磁氢谱（1H NMR）、核磁碳谱（13C NMR）、红外光谱（IR）和高分辨质谱（HRMS）进行确证,并通过热重-微热重-差示扫描量热（TG-DTG-DSC）分析方法对目标化合物的热稳定性进行分析。在空气氛围中,将目标化合物分别于300,600,900℃下进行热裂解,并通过气相色谱-质谱法对其挥发性热裂解产物进行定性和半定量分析。研究显示：目标化合物共经历了两次失重过程。第一次失重在129.9～158.9℃之间,失重2.3%;第二次失重在158.9～274.9℃之间,失重达90.1%,230.1℃时失重率最大。热裂解共产生44种产物,包括具有香味特征的大茴香醛、对甲基苯酚、松油醇、D-香茅醇、大茴香醚和茴香醚等化合物。其中裂解温度对裂解产物的种类和相对含量具有明显影响。300℃时α-二去氢菖蒲烯的相对含量最高,600,900℃时,相对含量最高的分别是大茴香醛和对甲基苯酚。苯甲醛、茴香醚和大茴香醚的相对含量随着温度的升高呈先增加后降低趋势;而对甲基苯酚含量则随着温度的升高而增加。根据主要裂解产物及其相对含量的变化,对目标化合物的裂解机理进行了初步探讨。

The pyrolysis behavior of 3-pyridine formic acid anisalcohol ester was analyzed by on-line pyrolysis/gas chromatography -mass spectrometry（Py/GC - MS）. Firstly, target compound 3-pyri- dine formic acid anisalcohol ester was synthesized by aeyl chlorination and esterification. The struc- ture of the target compound was confirmed by 1H NMR,13C NMR, IR and HRMS, and its stability was studied by the method of TG - DTG - DSC. In air atmosphere, target compound was pyrolyzed at 300, 600, 900 ℃, respectively. The pyrolysis products were analyzed by GC -MS qualitatively and semi-quantitatively. The result showed that the target compound experienced two mass loss. The first mass loss occurred between 129.9 ℃and 158.9 ℃ , and the mass loss was 2.3% . The second mass loss was between 158.9 ℃and 274.9 ℃, the mass loss reached up to 90. 1% , and the mass loss rate peaked at 230. 1 ℃. 44 kinds of compounds were detected, including flavor characteristic compounds such as 4-methoxy-benzaldehyde, 4-methyl-phenol, alpha-terpineol, 1-methoxy-4-meth- yl-benzene and methoxy-benzene. The result also indicated that pyrolysis temperature had significant effects on the type and relative content of pyrolysis products. The relative content of a-calacorene was the highest at 300 ℃, and the highest contents of 4-methoxy-benzaldehyde and 4-methyl-phenol were at 600 ℃ and 900 ℃, respectively. With the increase of pyrolysis temperature, the relative contents of benzaldehyde, metboxy-benzene and 1-methoxy-4-methyl-benzene increased at first and then de-creased, and the content of 4-methyl-phenol increased. According to the relative contents of pyrolysis products and their changes, the pyrolysis mechanism of target compound was preliminarily dicussed.