Enzymatic synthesis of pyridine heterocyclic compounds and their thermal stability
Longxin Wang,
Qianrui Zhao,
Guangpeng Wu,
Pengze Wang,
Meng Zhou,
Zhiyong Wu,
Miao Lai,
Mingqin Zhao
Affiliations
Longxin Wang
Flavors and Fragrance Engineering & Technology Research Center of Henan Province, College of Tobacco Science, Henan Agricultural University, #218 Ping'an Avenue Road, Zhengzhou, Henan Province, 450046, PR China
Qianrui Zhao
Flavors and Fragrance Engineering & Technology Research Center of Henan Province, College of Tobacco Science, Henan Agricultural University, #218 Ping'an Avenue Road, Zhengzhou, Henan Province, 450046, PR China
Guangpeng Wu
Henan Province Tobacco Company, #15 Business Outer Ring Road, Zhengzhou, Henan Province, 450046, PR China
Flavors and Fragrance Engineering & Technology Research Center of Henan Province, College of Tobacco Science, Henan Agricultural University, #218 Ping'an Avenue Road, Zhengzhou, Henan Province, 450046, PR China
Zhiyong Wu
Flavors and Fragrance Engineering & Technology Research Center of Henan Province, College of Tobacco Science, Henan Agricultural University, #218 Ping'an Avenue Road, Zhengzhou, Henan Province, 450046, PR China
Miao Lai
Flavors and Fragrance Engineering & Technology Research Center of Henan Province, College of Tobacco Science, Henan Agricultural University, #218 Ping'an Avenue Road, Zhengzhou, Henan Province, 450046, PR China; Corresponding author. Flavors and Fragrance Engineering & Technology Research Center of Henan Province, College of Tobacco Science, Henan Agricultural University, #218 Ping'an Avenue Road, Zhengzhou, Henan Province, 450046, PR China.
Mingqin Zhao
Flavors and Fragrance Engineering & Technology Research Center of Henan Province, College of Tobacco Science, Henan Agricultural University, #218 Ping'an Avenue Road, Zhengzhou, Henan Province, 450046, PR China
An efficient method was discovered for catalyzing the esterification under air using Novozym 435 to obtain pyridine esters. The following conditions were found to be optimal: 60 mg of Novozyme 435, 5.0 mL of n-hexane, a molar ratio of 2:1 for nicotinic acids (0.4 mmol) to alcohols (0.2 mmol), 0.25 g of molecular sieve 3A, a revolution speed of 150 rpm, a reaction temperature of 50 °C, and reaction time of 48 h. Under nine cycles of Novozym 435, the 80 % yield was consistently obtained. Optimum conditions were used to synthesize 23 pyridine esters, including five novel compounds. Among them, gas chromatography-mass spectrometry-olfactometry (GC-MS-O) showed phenethyl nicotinate (3g), (E)-hex-4-en-1-yl nicotinate (3m), and octyl nicotinate (3n) possessed strong aromas. Thermogravimetric analysis (TG) revealed that the compounds 3g, 3m and 3n exhibited stability at the specified temperature. This finding provides theoretical support for adding pyridine esters fragrance to high-temperature processed food.
