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Friedel–Crafts reactions have been used in the synthesis of several triarylmethane and xanthene dyes. [26] Examples are the synthesis of thymolphthalein (a pH indicator) from two equivalents of thymol and phthalic anhydride: A reaction of phthalic anhydride with resorcinol in the presence of zinc chloride gives the fluorophore fluorescein.
Phenols react to form esters instead of hydroxyarylketones when reacted with acyl halides under Friedel-Crafts acylation conditions. Therefore, this reaction is of industrial importance for the synthesis of hydroxyarylketones, which are important intermediates for several pharmaceuticals.
The cumene process (cumene-phenol process, Hock process) is an industrial process for synthesizing phenol and acetone from benzene and propylene. The term stems from cumene (isopropyl benzene), the intermediate material during the process. It was invented by R. Ūdris and P. Sergeyev in 1942 (USSR), [1] and independently by Heinrich Hock in ...
Phenethyl alcohol is prepared commercially via two routes. Most common is the Friedel-Crafts reaction between benzene and ethylene oxide in the presence of aluminium trichloride. C 6 H 6 + CH 2 CH 2 O + AlCl 3 → C 6 H 5 CH 2 CH 2 OAlCl 2 + HCl. The reaction affords the aluminium alkoxide that is subsequently hydrolyzed to the desired product.
The reaction is a type of Friedel-Crafts acylation with hydrogen chloride and a Lewis acid catalyst. The synthesis of 2,4,6-Trihydroxyacetophenone (THAP) from phloroglucinol is representative: [1] If two-equivalents are added, 2,4-Diacetylphloroglucinol is the product. Hoesch reaction example, 1-(2,4,6-trihydroxyphenyl)ethanone from phloroglucinol
This reaction is typically catalyzed by the corresponding iron or aluminum trihalide. The Friedel–Crafts reaction can be performed either as an acylation or as an alkylation. Often, aluminium trichloride is used, but almost any strong Lewis acid can be applied. For the acylation reaction a stoichiometric amount of aluminum trichloride is ...
Phenol reacts with dilute nitric acid at room temperature to give a mixture of 2-nitrophenol and 4-nitrophenol while with concentrated nitric acid, additional nitro groups are introduced, e.g. to give 2,4,6-trinitrophenol. Friedel Crafts alkylations of phenol and its derivatives often proceed without catalysts. Alkylating agents include alkyl ...
Similarly, hydroquinone is highly susceptible to ring substitution by Friedel–Crafts reactions such as alkylation. This reaction is exploited en route to popular antioxidants such as 2-tert-butyl-4-methoxyphenol . The useful dye quinizarin is produced by diacylation of hydroquinone with phthalic anhydride. [10]