Study On Friedel-Crafts Benzylation Of Arenas Catalyzed By Zn(OTf)₂

Friedel-Crafts alkylation is an important process for the synthesis of organic intermediates, especially for aromatic benzylation, which is a synthetically important fundamental transformation for the preparation of wide variety of diarylmethanes, which are key synthetic drug intermediates. The functionalization of arenes and heteroarenes is of great synthetic importance in the preparation of pharmaceuticals, agrochemicals, and fine chemicals. In a classical manner, as Friedel-Crafts alkylation is concerned, the reaction is generally performed using stoichiometric aluminium as a Lewis acid catalyst, which brings out serious effluent problems. Therefore, the development of novel Lewis acid catalyst like metal perfluorosulfonate has received continuous interest in recent years, the catalyst work with notable results in the aromatic benzylation.In this paper, we used metal bis(perfluorosulfonate) as Lewis acid catalyst for Friedel-Crafts alkylation. Disinfectant 2-benzyl-4-chlorophenol is prepared by benzylation reactions. We also research other different substrates, such as anisole, toluene and benzene. The aromatic benzylation reactions were studied under various conditions. Our work was mainly described as follows:1. The work is about the process for the synthesis of 2-benzyl-4-chlorophenol using nitromethanc as solvent and metal perfluorosulfonate as catalyst at different temperature from p - chlorophenol and benzylchloride in different reaction conditions, such as ratios of starting materials, temperatures, catalysts etc. The optimal conditions are as follows: nitromethanc as solvent, 1.2:1 molar ratio of p-chlorophenol to benzyl chloride, 5% molar amount of Zn(OTf)2 according to benzyl chloride at 60℃, reaction time 6 h, with the yield of 93.8%.2. The benzylation reactions of other different substrates (such as anisole, toluene and benzene) are researched. The reactions were studied under various conditions. The optimal conditions are as follows: nitromethanc as solvent, 5% molar amount of Zn(OTf)2 according to benzyl chloride at 60℃, reaction time 6 h, with the conversion of 100%, the isolated yield for the products of anisole, toluene and benzene are 84.2%, 71.0% and 67.1%.