Daniel M. Baier, Tilo Rensch, Desislava Dobreva, Carolina Spula, Stephen Fanenstich, Marisol Rappen, Konrad Bergheim, Dr. Sven Grätz, Prof. Dr. Lars Borchardt
{"title":"The Mechanochemical Beckmann Rearrangement over Solid Acids: From the Ball Mill to the Extruder","authors":"Daniel M. Baier, Tilo Rensch, Desislava Dobreva, Carolina Spula, Stephen Fanenstich, Marisol Rappen, Konrad Bergheim, Dr. Sven Grätz, Prof. Dr. Lars Borchardt","doi":"10.1002/cmtd.202200058","DOIUrl":null,"url":null,"abstract":"<p>Beckmann rearrangement was carried out in the solid state in a ball mill using metal oxides as solid acids. After a comprehensive investigation of different reaction parameters, acids as well as further additives, a combination of aluminosilicate materials, phosphorus pentoxide, and para-toluenesulfonic acid was identified as the optimal system. This allowed the model compounds ϵ-caprolactam and acetanilide to be obtained in yields of 46 % and 94 %, respectively, while the robustness of the method was demonstrated by applying it to additional substrates. Finally, we scaled up our optimized reaction into a continuous process using a twin screw extruder. With this, yields beyond 90 % could be achieved in a residence time as low as seven minutes.</p>","PeriodicalId":72562,"journal":{"name":"Chemistry methods : new approaches to solving problems in chemistry","volume":null,"pages":null},"PeriodicalIF":6.1000,"publicationDate":"2022-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/cmtd.202200058","citationCount":"2","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Chemistry methods : new approaches to solving problems in chemistry","FirstCategoryId":"1085","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/cmtd.202200058","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 2
Abstract
Beckmann rearrangement was carried out in the solid state in a ball mill using metal oxides as solid acids. After a comprehensive investigation of different reaction parameters, acids as well as further additives, a combination of aluminosilicate materials, phosphorus pentoxide, and para-toluenesulfonic acid was identified as the optimal system. This allowed the model compounds ϵ-caprolactam and acetanilide to be obtained in yields of 46 % and 94 %, respectively, while the robustness of the method was demonstrated by applying it to additional substrates. Finally, we scaled up our optimized reaction into a continuous process using a twin screw extruder. With this, yields beyond 90 % could be achieved in a residence time as low as seven minutes.