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Computational and experimental approach to evaluate the effect of initiator concentration, solvents, and enes on TEMPO driven thiol-ene reaction
New Journal of Chemistry ( IF 2.7 ) Pub Date : 2020-09-30 , DOI: 10.1039/d0nj02882g
Sumbul Hafeez 1, 2, 3, 4 , Vikas Khatri 2, 3, 4, 5 , Hemant K. Kashyap 2, 3, 4, 5 , Leena Nebhani 1, 2, 3, 4
Affiliation  

The fundamental mechanism and reaction kinetics of TEMPO (2,2,6,6-tetramethyl piperidin-1-yl)oxyl) initiated thiol-ene reaction between benzyl mercaptan and variable enes (divinyl sulfone, n-butyl acrylate, N,N-dimethylacrylamide, vinyltriethoxysilane and 1-dodecene), in the presence of varying initiator concentrations (0, 0.01, 0.05, 0.08 and 0.1 mmol) and varying solvents (methanol, tetrahydrofuran and chloroform) were studied experimentally and computationally. The DFT (density functional theory) calculations have been used to investigate the effect of variable enes on the thiol-ene reactions. From the computational and experimental results, it can be concluded that the varying initiator concentrations, varying solvents and nature of enes directly influences the TEMPO initiated thiol-ene reaction. For TEMPO initiated thiol-ene reaction, electron-deficient enes, such as divinyl sulfone, and n-butyl acrylate, exhibited quantitative conversion in 8 h using methanol as solvent at 35 °C, however electron-rich ene, such as vinyltriethoxysilane, showed no thioether formation and 1-dodecene showed 30% conversion in 8 h using methanol as solvent at 35 °C. The reaction between benzyl mercaptan and electron deficient enes, such as divinyl sulfone, n-butyl acrylate and N,N-dimethylacrylamide, exhibited quantitative conversion in 16 h using chloroform and tetrahydrofuran as solvent at ambient temperature. All the experimental studies were monitored by 1H NMR spectroscopy. Additionally, the reactivity of ene toward the thiol-ene reaction was also determined using DFT calculation, which was found to be in agreement with the experimental data. Methanol as a solvent exhibited higher reactivity towards TEMPO initiated thiol-ene reaction as compared to tetrahydrofuran and chloroform, which was demonstrated by the solvation model based on density (SMD).

中文翻译:

评估引发剂浓度,溶剂和烯对TEMPO驱动的硫醇-烯反应的影响的计算和实验方法

TEMPO(2,2,6,6-四甲基哌啶-1-基)氧基的基本机理和反应动力学引发了硫醇与苄基硫醇(二乙烯基砜,丙烯酸正丁酯,N,N-通过实验和计算研究了在变化的引发剂浓度(0、0.01、0.05、0.08和0.1 mmol)和变化的溶剂(甲醇,四氢呋喃和氯仿)存在下的二甲基丙烯酰胺,乙烯基三乙氧基硅烷和1-十二碳烯。DFT(密度泛函理论)计算已用于研究可变烯对硫醇-烯反应的影响。从计算和实验结果可以得出结论,引发剂浓度的变化,溶剂的变化和烯的性质直接影响TEMPO引发的硫醇-烯反应。对于TEMPO引发的硫醇-烯反应,缺电子的烯,例如二乙烯基砜和丙烯酸正丁酯,在35°C下使用甲醇作为溶剂,在8小时内显示出定量转化,但是富含电子的烯,例如乙烯基三乙氧基硅烷,未显示出硫醚的形成,并且显示了1-十二碳烯在35°C下使用甲醇作为溶剂,在8小时内转化率为30%。苄硫醇与缺电子的烯(例如二乙烯基砜,丙烯酸正丁酯和N,N-二甲基丙烯酰胺)之间的反应在室温下以氯仿和四氢呋喃为溶剂在16小时内表现出定量转化。所有实验研究均通过1H NMR光谱进行监控。另外,还使用DFT计算来确定烯对硫醇-烯反应的反应性,发现其与实验数据一致。
更新日期:2020-09-30
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