Synthesis and pyrolysis of methyl cyclopentenolone succinate diester

Abstract

To develop a new class of enol diketone esters, succinic acid monoesters were synthesized using the reaction of succinic anhydride with various aromatic alcohols. Subsequently, six types of methyl cyclopentenolone succinate diesters were synthesized using dicyclohexylcarbodiimide (DCC) as the condensation agent and 4-dimethylaminopyridine (DMAP) as the catalyst for the condensation reaction with methyl cyclopentenolone. The target compounds were characterized by nuclear magnetic resonance (¹H NMR, ¹³C NMR), infrared spectroscopy (IR) and high-resolution mass spectrometry (HRMS). The aromas characteristics of esters were evaluated using gas chromatography–mass spectrometry-olfactometer (GC–MS-O). Compounds 5a ~ 5c, which had a strong aroma, were conducted with thermogravimetry-derivative thermogravimetry (TG-DTG) to analyse their heating-stability. Additionally, these compounds were studied by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) to analyse their pyrolysis behaviours at 300, 350 and 400°C. Results showed that methyl cyclopentenolone and a large number of small molecular flavouring substances were formed by 5a ~ 5c at the set temperature. The synthesis of methyl cyclopentenolone succinate diester can not only slow down the volatilization of methyl cyclopentenolone and aromatic alcohol, but also effectively enhance the aroma, improve the smoking taste of cigarettes, reduce the irritation and miscellaneous gas of smoking and provide more choices for cigarette flavouring.