新型甲酰基吡咯衍生物的合成及其热裂解-气相色谱/质谱分析

Synthesis of New Formacyl-pyrrole Derivative and Its Analysis by Pyrolysis-Gas Chromatography/Mass Spectrometry

本文以D-(+)-氨基葡萄糖盐酸盐为原料,通过环合、氧化和烷基化等系列反应,合成了新型化合物N-戊基-2-甲基-3-乙酰基-5-吡咯甲醛,并利用红外(IR)光谱、核磁共振(~1H NMR、^(13)C NMR)和高分辨质谱(HR-MS)等波谱技术对其结构进行了确证。采用正交试验优化了合成条件,通过热重-微分热重-差示扫描量热法(TG-DTG-DSC)研究了该化合物热失重变化,采用热裂解-气相色谱/质谱(Py-GC/MS)联用技术分析了该化合物的热裂解产物。结果表明化合物Ⅳ为目标化合物N-戊基-2-甲基-3-乙酰基-5-吡咯甲醛。目标化合物的最优合成条件为:反应温度60℃、反应时间24h、摩尔比1.0∶1.1,产率可达81%;目标化合物在136.3~290.0℃间有一个剧烈的失重过程,失重率达到98.58%;目标化合物在300、600、900℃裂解条件下共裂解出41种化合物,其中有吡嗪、2,5-二甲基吡嗪、戊醛等多种香味成分。初步探讨了目标化合物可能的热裂解机理。

In order to develop a new flavor precursor of pyrroles,a new compound,3-acetyl-N-amyl-2-methyl-5-pyrrolecarboxaldehyde was synthesized by cyclization reaction,oxidation reaction and alkylation reaction.Its structure was confirmed by 1H NMR,13C NMR,IR and HR-MS spectra.The optimal conditions for synthesis were obtained by orthogonal array design.Its thermal stabilities were studied by using themogravimetry-derivative themogravimetry-differential scanning calorimetry（TG-DTG-DSC）.And its pyrolytic products were analyzed by pyrolysis-gas chromatography/mass spectrometry（Py-GC/MS）.The result showed that the target compound,was successfully synthesized.The optimal synthesis conditions were obtained as follows：reaction temperature 60℃,reaction time 24 h,mole ratio 1.0∶1.1.Under the optimal synthesis conditions,the reaction yield could reach 81%.Target compound had a severe degradation stage at 136.3-290.0 ℃ with mass loss of 98.58%.41 prolysis products including flavorous substances pyrazine,2,-5-dimethyl pyrazine and pentanal were detected at 300,600,900℃,and possible pyrolysis mechanism of target compound was preliminarily discussed.