Aromatic substitution in ball mills: formation of aryl chlorides and bromides using potassium peroxomonosulfate and NaX
作者:Robert Schmidt、Achim Stolle、Bernd Ondruschka
DOI:10.1039/c2gc16508b
日期:——
Aryl chlorides and bromides are formed from arenes in a ball mill using KHSO5 and NaX (X = Cl, Br) as oxidant and halogen source, respectively. Investigation of the reaction parameters identified operating frequency, milling time, and the number of milling balls as the main influencing variables, as these determine the amount of energy provided to the reaction system. Assessment of liquid-assisted grinding conditions revealed, that the addition of solvents has no advantageous effect in this special case. Preferably activated arenes are halogenated, whereby bromination afforded higher product yields than chlorination. Most often reactions are regio- and chemoselective, since p-substitution was preferred and concurring side-chain oxidation of alkylated arenes by KHSO5 was not observed.
芳基氯和芳基溴是通过在球磨机中使用KHSO5和NaX(X=Cl,Br)分别作为氧化剂和卤素源,从芳烃形成的。对反应参数的调查确定操作频率、研磨时间和研磨球数为主要影响变量,因为这些变量决定了向反应系统提供的能量。对液体辅助研磨条件的评估揭示,在这种特殊情况下,溶剂的添加没有优势效应。优先激活的芳烃被卤化,其中溴化得到的产物收率高于氯化。大多数反应具有区域选择性和化学选择性,因为更喜欢对位取代,而且没有观察到KHSO5对烷基化芳烃侧链的氧化作用。