Moisture Property and Thermal Behavior of Two Novel Synthesized Polyol Pyrrole Esters in Tobacco

Abstract

To overcome the shortcomings of high relative humidity and harmful oxidation products from traditional humectants, excellent humectants and flavor precursors were reported herein. Glucosamine hydrochloride was used as the starting material for the cyclization, oxidation, and alkylation processes that produced pyrrole acid. Then, esterification occurred with polyol catalyzed by EDC and DMAP to give the target compounds 2-(2,3-dihydroxypropyl) 4-methyl 5-methyl-1-propyl-1H-pyrrole-2,4-dicarboxylate (Gpe) and (2-hydroxypropyl) 4-methyl 5-methyl-1-propyl-1H-pyrrole-2,4-dicarboxylate (Ppe). Nuclear magnetic resonance (1H NMR, 13C NMR), infrared spectroscopy (IR), and high-resolution mass recorded spectrometry (HRMS) were used to confirm the two novel polyol pyrrole ester compounds. When Gpe and Ppe were added to the tobacco shred, low-field nuclear magnetic resonance (LF-NMR) imaging was applied to assess the hygroscopicity and moisturizing capacity. Furthermore, thermogravimetry (TG) and pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) techniques were applied to study their thermal behaviors. These results showed that the target compounds (Gpe and Ppe) are good humectants with thermal properties of high-temperature stability and flavor release.

Synthesis, Thermal Stability and Antifungal Evaluation of Two New Pyrrole Esters

“…Originally, compound 3 was observed when the ester bond O=C‐O of target compounds were broken, meanwhile vanillin and ethyl maltol from 4a and 4b were released, respectively. Depropyl reaction at 1‐position and decarbonylative reaction of compound 3 happened under pyrolytic conditions, culminating in the synthesis of 2‐methyl‐1H‐pyrrole [47] . These findings corroborated our original concepts for constructing the target compounds′ synthetic routes.…”

“…Depropyl reaction at 1-position and decarbonylative reaction of compound 3 happened under pyrolytic conditions, culminating in the synthesis of 2-methyl-1H-pyrrole. [47] These findings corroborated our original concepts for constructing the target compounds' synthetic routes. It was discovered that pyrrole ester derivatives have good thermal stability and have the effect of taste slow-release at high temperatures.…”

“…These flavor compounds have been detected in various foods, including chocolate, biscuits, puddings, cakes, beverages, soya bean, and milk powder [42,43] . Furthermore, recent research revealed that these compounds also have appetite‐enhancing effects [46,47] …”

“…Ethyl alcohol was used to extract the combination, and the content of organic extract were then washed with brine and water, dried over MgSO 4 , and condensed. By recrystallization, the anticipated compound 3 was produced [47] …”

“…[42,43] Furthermore, recent research revealed that these compounds also have appetite-enhancing effects. [46,47] The possible pyrolytic mechanism of 4a and 4b were presented in Figure 2. Interestingly, the main pyrolytic products of 4a and 4b were raw materials which were utilized to synthesize them.…”