Xiaoyan Zheng,Tianhao Zhang,Jie Li,Guoliang Zhang,Hongnan Chen,Shasha Cao,Chunshan Li,Guangzhou Jin
2-Ethyl-3-oxazolidineethanol (OE) is an important pharmaceutical intermediate for the treatment of dental plaque. A systematic investigation of the one-pot synthesis of OE from propanal (PA) and diethanolamine (DEA) was conducted herein. The process was carried out under mild reaction conditions without any addition of catalyst, and the product was characterized by Fourier transform infrared spectroscopy (FT-IR), 1H nuclear magnetic resonance (NMR), and electrospray ionization-tandem mass spectrometry (ESI-MS/MS). Additionally, the effects of the PA/DEA ratio, methanol/DEA ratio, reaction time, and temperature on the reaction results were explored. Based on the single-factor experiments, response surface methodology (RSM) was used to optimize the reaction conditions and it achieved a high OE yield of 98.48%, which is close to the prediction value of 98.38%. Furthermore, the reaction kinetics were calculated utilizing the second-order kinetic model, and activation energies of the forward and reverse reactions were 31.35 and 41.85 kJ·mol–1, respectively. Under the optimization reaction conditions, OE was efficiently synthesized, indicating a significant potential for industrial applications.
Mingji Xiao,Fangling Zheng,Mengxuan Xiao,An Qi,Huiqiang Wang,Qianying Dai
In China, Lu'an Guapian (LAGP) tea consists of tea leaves without tea buds or stems. In this study, we evaluated the aromatic characteristics of LAGP by sensory analysis, aroma extract dilution analysis (AEDA), and odor activity values. The sensory analysis revealed that LAGP had cooked soybean-like, cooked chestnut-like, roasted, cooked corn-like, fishy, fruity, floral, and grass aromas. Aroma-active compounds from LAGP were identified by solvent extraction-solid phase extraction (SE-SPE) and headspace-solid phase microextraction (HS-SPME), and subjected to AEDA. A total of 91 aroma-active compounds were identified by SE-SPE-AEDA with flavor dilution (FD) factors ranging from 1 to 4096. A total of 66 aroma-active compounds were identified by HS-SPME-AEDA with FD of 1 to 128. Nine compounds with FD ≥64 and OAVs ≥1 were major aroma-active compounds to the aroma of LAGP tea: raspberry ketone (raspberry), ( E )- β -ionone (floral, raspberry), dimethyl sulfide (cooked corn-like), indole (animal), phenylacetaldehyde (floral, honey-like), 2-ethyl-3,5-dimethylpyrazine (roasted), ( Z )-4-heptenal (cooked soybean-like, fishy), ( Z )-jasmone (jasmine), and geraniol (rose).
危险品化学品经营许可证（带存储）