Improved synthesis of perfluoroalkyl substituted 1,3,4-oxadiazoles as precursors for corresponding 1,2,4-triazoles
作者:Mariano Grünebaum、Anna I. Gerlitz、Annika Buchheit、Steffen Jeschke、Constantin G. Daniliuc、Hans-D. Wiemhöfer
DOI:10.1016/j.jfluchem.2016.01.006
日期:2016.3
An improved and more efficient synthesis of 2,5-bis(trifluoromethyl)-1,3,4-oxadiazole (2a), 2,5-bis(perfluoroethyl)-1,3,4-oxadiazole (2b), 2-(perfluoroethyl)-5-(trifluoromethyl)-1,3,4-oxadiazole (2d) and 2-(perfluoroheptyl)-5-(trifluoromethyl)-1,3,4-oxadiazole (2e), via ring-opening reactions of the corresponding sodium 5perfluoroalkyltetrazolates (10a-b) is described. Furthermore the named perfluoroalkyl-1
2,5-双(三氟甲基)-1,3,4-恶二唑(2a),2,5-双(全氟乙基)-1,3,4-恶二唑(2b),2-(全氟乙基)-5-(三氟甲基)-1,3,4-恶二唑(2d)和2-(全氟庚基)-5-(三氟甲基)-1,3,4-恶二唑(2e)描述了相应的5全氟烷基四唑酸钠(10a-b)。此外,将命名的全氟烷基-1,3,4-恶二唑(2a-b和2d)转化为相应的3,5-双(三氟甲基)-1,2,4-三唑(1a),3,5-双(全氟乙基)-1,2,4-三唑(1b)和5-(全氟乙基)-3-(三氟甲基)-1,2,4-三唑(1d),原位生成氨(尿素和氢氧化钾)。使用多核(1 H,13 C,19 F)NMR光谱和差示扫描量热法对所有产品进行表征,以确定其结构和热力学特征。另外,通过单晶X射线衍射确定1a的分子结构。