Evaluation of a Nonresonant Microwave Applicator for Continuous-Flow Chemistry Applications

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• 作者：Per 脰hrngren ; Ashkan Fardost ; Francesco Russo ; Jon-Sverre Schanche ; Magnus Fagrell ; Mats Larhed
• 刊名：Organic Process Research & Development
• 出版年：2012
• 出版时间：May 18, 2012
• 年：2012
• 卷：16
• 期：5
• 页码：1053-1063
• 全文大小：439K
• 年卷期：v.16,no.5(May 18, 2012)
• ISSN：1520-586X

文摘

The concept of a nonresonant microwave applicator for continuous-flow organic chemistry is introduced and evaluated. The frequency of the incident microwave radiation can be adjusted between 2.4 and 2.5 GHz to optimize the energy absorbance. The temperature of the reaction is monitored by five IR sensors, and their signals can be used to automatically adjust the power output from the microwave generator. The heating of several different solvents up to 20 掳C above the standard boiling point has been explored. Several different organic reactions have been successfully carried out using a 200 mm 脳 3 mm tubular borosilicate reactor and a flow between 47 and 2120 渭L/min. The microwave heating pattern was visualized with an IR camera. The transformations include palladium-catalyzed coupling reactions (oxidative Heck and Suzuki reactions), heterocyclic chemistry (oxathiazolone and Fischer indole synthesis), rearrangement (Claisen), and a Diels鈥揂lder cycloaddition reaction. A scale-out to 57 mmol/h was performed with the Fischer indole reaction.