Friedel-crafts processes

In the acid-catalysis method, a proton or Lewis acid is used as the catalyst and the reaction is carried out at temperatures between -30 and 100°C. This is a Friedel-Crafts process with a carbocation mechanism" (illustrated for a proton acid... 

ZSM-5 is also used as the catalyst in the production of monoethyl benzene from benzene and ethene it is highly selective for the mono-substituted product, which is the precursor of styrene, and again does not use the harmful aluminium chloride, which the old Friedel-Crafts process employed. 

The Friedel-Crafts process (84,85) produces most of the PEA presendy being manufactured. 

The reactions of carbohydrate derivatives with certain organometallic reagents (Grignard and Friedel-Crafts processes) have been reviewed in this Series and elsewhere.87 The attempted application of a Chugaev reaction to sugar xanthates was reported by Wolfram and Foster.88 It was found,... 

Other well-known reactions are those offluorinated olefins with fluoride ion and negatively substituted aromatic compounds leading to the formation of per-fluoroalkylated aromatic compounds The reaction may be considered an anionic version ot a Friedel Crafts process and can result m introduction of one or several perfluoroalkyl substituents [HI] Aromatic substrates include substituted and unsubstituted perfluorobenzenes [131, 212, 213, 214], fluorinated heterocycles [131, 203, 215, 216, 217, 218, 219, 220, 221, 222, 223], perchlonnated heterocycles [224] (equation 44), and other activated aromatic compounds [225] (equation 45) The fluorinated olefins can be linear or cyclic [208] (equation 46)... 

Manufacture. Current commercial methods for making PEA include Grignard synthesis. Friedel-Crafts process, and catalytic hydrogenation of styrene oxide. 

This process was superceded by the Friedel-Crafts reaction of benzene and ethylene oxide which is now the most important commercial process (11). Cheap ethylene oxide brought about this shift. For a short time, commercial quantities of phenylethyl alcohol were made by the Grignard reaction of phenyl magnesium chloride on ethylene oxide but this process could not compete with the Friedel-Crafts process. 

Owing to its powerful Lewis acidity, BF3 is an effective reagent in organic synthesis, for example, promoting the conversion of alcohols and acids to esters, the polymerization of olefins and olefin oxides, and acylations and alkylations (in a manner similar to Friedel-Crafts processes). Mechanistic studies of some reactions of the latter type, such as the ethylation of benzene by QH5F, have shown that the BF3 functions as a scavenger for HF via the formation of HBF4 and thus participates stoichiometrically rather than catalytically. 

Friedel-Crafts process, in the carbohydrate series, VI, 251-289 Fructans, II, 253-277 Fructofuranoside, a-D-glucopyranosyl /3-d-, IV, 1-35 Fructosans, poly-. See Fructans. Fructose,... 

Derivation (1) Friedel-Crafts process with benzene and acetic anhydride or acetyl chloride (2) by-product from the oxidation of cumene (3) oxidation of ethylbenzene. 

Sartori, G., Bigi, R, Maggi, R., Baraldi, D., and Casnati, G. 1992. Acylation of aroyl chlorides via a template Friedel-Crafts process synthesis of indan-l,3-diones. /. Chem. Soc., Perkin Trans. 1 2985-2988. 

Disposal of the solutions of aluminum salts generated in the Friedel-Crafts process presents an environmental problem unless use can be found for them as coagulants in a water treatment plant. 

Pyridinyltin reagents also provide a means for the effective acylation of a pyridine, unachievable by conventional Friedel-Crafts processes, as discussed earlier, and illustrated above by 2-t-butoxycarbonylation. ... 

The alkylation of toluene with nrethanol is readily catalyzed on synthetic zeolites. Previous work has shown that the aromatic-ring alkylation of toluene with methanol takes place over acid zeolites [1], while the side-chain alkylation occurs preferentialty over basic zeolites [2,3]. The side-chain alkylation of toluene with methanol, for producing a mbrtuie of styrene and ethylbenzene offers economical advantages conpared with the conventional homogeneously catalyzed Friedel-Crafts process, which use ethylene and benzene as reactants [4]. 

---