Benzoic anhydride anisole benzoylation

Friedel-Crafts Acylation, Alkylation, and Related Reactions. While a stoichiometric amount of AICI3 is needed in Friedel-Crafts acylations, a small amount of Sc(OTf)3 smoothly catalyzes the same reaction. In the acetylation of thioanisole and o- or m-dimethoxybenzene, a single acetylated product is formed in an excellent yield. In the benzoylation of anisole, both benzoic anhydride and benzoyl chloride are effective, while benzoic anhydride gives a slightly higher yield. Addition of lithium perchlorate (LiC104) as a cocatalyst improves the yield dramatically (eq 13). ... 

Hardacre et al. report the Friedel-Crafts benzoylation of anisole with benzoic anhydride to yield 4-methoxybenzophenone with various ILs and zeolite catalysts (USY, HZSM-5, H-beta, and H-mordenite). The rates of reaction were found to be significantly higher using ionic liquids compared with organic solvents.Continuous-flow studies of successful ionic liquid systems indicate that the bulk of the catalysis is due to the formation of an acid via the ion exchange of the cation with the protons of the zeolite as shown in the following reaction. Scheme 8. 

Scheme 4.1 Benzoylation reaction of anisole with benzoic anhydride.

The formation of 4-methoxybenzophenone by the benzoylation of anisole with benzoic anhydride is shown in Scheme 4.1. 

Diarylketones are also the important fine chemical intermediates, which could be prepared by the acylation of aromatic hydrocarbon with benzoyl chloride and benzoic anhydride. The ionic liquids have also been used to catalyze the synthesis of diarylke-tone. Earle et al. [105] have reported the benzoylation of benzene, derivants of benzene (toluene, anisole, isobutyl benzene, phenyl chloride and fluoride) to synthesize the diarylketone by use of chloroindate (III) ionic liquids as the green dual catalysts and solvents. As a result, good yields (75-96%) were obtained under proper conditions with the ionic liquids as the clean reaction medium and recyclable catalysts. 

Izumi et al. pioneered the use of heteropoly acids as catalysts for aromatic acylation. Silica-supported acids H4[SiWi204o] and H3[PWi204o] were found to effectively catalyse the acylation of p-xylene with benzoyl chloride. Cs2.5Ho.5[PWi204o] showed high efficiency in the acylation of activated arenes, such as p-xylene, anisole, mesitylene, etc., by acetic and benzoic anhydrides and acyl chlorides. This catalyst provided higher yields of acylated arenes than the parent acid H3[PWi204o], the latter being partly soluble in the reaction mixture. ... 

Electron-rich aromatic compounds such as durene, p-dimethoxybenzene, mesitylene, anisole, thiophene, and fluorene can be benzoylated or acetylated by the corresponding Af-acylimidazole in trifluoroacetic acid to give the corresponding benzophenone or acetophenone derivative in good yield (Method A). As the actual acylating agent, a mixed anhydride of trifluoroacetic acid and benzoic acid has been proposed 1973... 

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