Synthesis and pyrolysis of two flavor precursors of oct-1-en-3-yl methylpyrazinecarboxylates

Abstract

To rich flavor additive species of pyrazines, two new compounds of 3,6-dimethyl-2,5-pyrazinedicarboxylic acid 1-octen-3-yl ester (DMPOE) and 3,5,6-trimethyl-2-pyrazinecarboxylic acid 1-octen-3-yl ester (TMPOE) were synthesized by KMnO4 oxidation, acylating chlorination and esterification reaction, in which tetramethylpyrazine and 1-octen-3-ol were used as initial materials. Thermogravimetry (TG), differential scanning calorimeter (DSC) and pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) were conducted to investigate the thermal degradation behaviors of DMPOE and TMPOE. TG–DTG results indicated that the T p of DMPOE and TMPOE with the largest mass loss rate was at 310 and 250 °C, respectively. The T peak of DMPOE and TMPOE showed by DSC curves was 301.8 and 260.0 °C, respectively. Py–GC/MS was performed to benefit the simulation of cigarette burning conditions, and the results indicated that DMPOE and TMPOE could release specific flavors of 1-octen-3-ol and diversified alkylpyrazines. Furthermore, the thermal degradation mechanisms of the flavor precursors of DMPOE and TMPOE were discussed. The study on the thermal behavior of these two methylpyrazinecarboxylates would provide theoretical basis for their application in tobacco.