Enzyme‐Catalyzed Synthesis, Odor Characteristics and Thermal Analysis of New Pyridine Esters. Issue 10 (10th March 2023)

• Record Type: Journal Article
• Authors: Zhao, Qianrui; Wang, Longxin; Chen, Haoran; Wu, Zhiyong; Zhao, Mingqin; Lai, Miao
• Is Part Of: ChemistrySelect. Volume 8:Issue 10(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-03-10
• Subjects: enzymatic transesterification -- GC-MS-O -- pyridyl esters -- thermogravimetry; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/slct.202204356
• Languages: English
• ISSNs: 2365-6549

Abstract

Abstract: A new method for the efficient conversion of pyridine methanols and ethyl carboxylates to pyridine esters in air catalyzed by Novozym 435 (N435) was reported. The enzyme catalyzed transesterification reaction was performed under the optimum conditions: N435 (60 mg) as a biocatalyst, acetonitrile (2.5 mL) as a solvent, the molar ratio of pyridine methanols (0.2 mmol) to ethyl carboxylats (1.0 mmol) of 1 : 5, molecular sieve 3 A of 1.00 g, reaction temperature of 50 °C, the revolution speed of 150 rpm and reaction time of 36 h. The enzyme still retained a yield of 80 % after repeated use for 10 times. Under optimal conditions, eighteen pyridine esters were synthesized in this paper, containing fifteen esters as novel compounds. The synthesized pyridine esters were analyzed by gas chromatography‐mass spectrometry‐olfactory (GC‐MS‐O), of which four pyridyl esters including compounds 3 a, 3 c, 3 g and 3 r possessed strong aromas which were based on peak area in GC‐MS. Thermogravimetric analysis (TG) was performed on these four flavor compounds. According to the results of TG analysis, they had good thermal stability at the certain temperature. Abstract : The λenzymatic synthesis reaction conditions of novel pyridine esters from pyridine methanols and ethyl carboxylates are optimized. The characterization of synthesized pyridine esters included 1 H NMR, 13 C NMR, IR, HRMS. The odor characteristics of the obtained pyridine esters were evaluated by GC‐MS‐O. The thermal analysis of the five pyridine esters with special aroma were investigated by TG and DSC.