Ferric chloride catalyst activator

Cobalt boride has been used for reducing unsaturated aldehydes to unsaturated alcohols improved results are obtained by addition of ferric chloride or chromium chloride (6S). It is a low-activity catalyst. 

The metal halide catalysts include aluminum chloride, aluminum bromide, ferric chloride, zinc chloride, stannic chloride, titanium tetrachloride and other halides of the group known as the Friedel-Crafts catalysts. Boron fluoride, a nonmetal halide, has an activity similar to that of aluminum chloride. 

Proton acids can be used as catalysts when the reagent is a carboxylic acid. The mixed carboxylic sulfonic anhydrides RCOOSO2CF3 are extremely reactive acylating agents and can smoothly acylate benzene without a catalyst.265 With active substrates (e.g., aryl ethers, fused-ring systems, thiophenes), Friedel-Crafts acylation can be carried out with very small amounts of catalyst, often just a trace, or even sometimes with no catalyst at all. Ferric chloride, iodine, zinc chloride, and iron are the most common catalysts when the reactions is carried out in this manner.266... 

Catalysts. It was shown by Friedel and Crafts that while aluminum chloride is a very active alkylation catalyst, other metal chlorides (ferric chloride, zinc chloride, etc.) are also effective. They also showed that other aluminum halides (aluminum... 

The catalysts or condensing agents which have been employed most frequently for intramolecular acylation by the Friedel-Crafts method are aluminum chloride and the less active stannic chloride. Mention of the use of the intermediately active ferric chloride may be found,12 but the generality of this procedure has not been demonstrated. 

Camosic acid is very unstable in the presence of aqueous solvents, but it is stable in nonpolar organic solvents. Curvelier et al. [26] have also observed the formation of several oxidation products of camosic acid when it is dissolved in methanol. The instability of camosic acid is probably due to air oxidation catalyzed by a transition metal ion such as iron, which often exists as impurity in polar solvents. It has been observed by Masuda et al. [25] that addition of a catalyst amount of ferric chloride to a solution of carbonic acid in acetonitrile leads the formation of products (92) and (93) in low yield. It has been found that the oxidation products do not show any activity. This observation confirms... 

The gold compounds were amongst the most active catalysts but it is now known that other Lewis acid catalysts such as ferric chloride are superior for this reaction. 

The polymerisation of benzene through repeated nucleophilic substitutions on the rings was studied by Kovacic et al. using ferric chloride as catalyst and water as cocatalyst. This system is of course outeide the realm of cationic polymerisation throu the double bcmd of an olefin, but illustrates well the role of water in Friedel-Crafts polycondensations. The authors showed that the rate of this reaction went throu a maximum at a catalyst/cocatalyst ratio of one and attributed this observation to the high activity of ferric chloride monohydrate ... 

Up to now several methods have been used to prepare iron molybdates, the most part of them based on coprecipitation techniques. Previous studies [11] have evidenced that the catalytic behavior of Mo-Fe oxides depends on many variables of the coprecipitation procedure starting compounds, concentration of parent solutions, pH and temperature of coprecipitation step, order of addition of parent solutions, ripening etc. In a typical preparation procedure iron molybdate is coprecipitated from solutions of ferric chloride or ferric nitrate and ammonium molybdate [8]. The control of all the above mentioned procedure variables, strongly difficult the preparation of these catalysts and deviations from the preparation recipe can have very adverse effects on the performances of the catalyst from the standpoint of activity, selectivity and stability. 

Consequently, a lot of research has been carried out in this area in order to find convenient catalysts, i.e. those able to activate the acylating reagent while giving labile complexes with ketones, in particular in hot conditions. Ferric chloride is the most common catalyst when the reaction is achieved in this manner (refs. 7, 8). With this same view, Friedel-Crafts acylation in the presence of small quantities of catalysts (for example FeCl3), is strongly activated by microwave irradiation, in particular when the catalyst is on a graphite substrate (ref. 9). 

Reactions of an alcohol with acetic anhydride are greatly accelerated by acid catalysts, such as sulfuric acid, zinc chloride, phosphorus pentoxide, ferric chloride, etc. However, such catalysts cannot be used with sensitive alcohols, such as linalool, which are isomerized or otherwise affected by them. The effective acid strength of a catalyst in an anhydrous medium is the predominant factor in determining its activity. The acidities of mineral acids in glacial acetic acid correspond remarkably well with their activities as acetylation catalysts. Sulfuric and perchloric acids in acetic acid solution have been termed superacid solutions because of thdr exceptional strength as compared with the strength of other acids. Most anhydrides react more rapidly with an alcohol in the presence of a base. The base can be sodium hydroxide, the sodium salt of the acid, or a tertiary amine, which can also be the solvent for the reaction. ... 

Very active catalysts such as aluminum chloride often lead to significant amounts of meta products, even when the aromatic ring contains activating substituents, 0a,h,9l which is due to the thermodynamic nature of the reaction with aluminum chloride and the thermodynamic preference for the meta product. Excess catalyst and high reaction temperatures also favor more meta product. The use of BF3, sulfuric acid, ferric chloride (FeCl3) and zinc chloride (ZnCl2), in lower concentrations and at lower temperatures, gives primarily the expected ortho-para products. ... 

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