Alkylation Friedel-Crafts reactions

There are relatively few kinetic data on the Friedel-Crafts reaction. Alkylation of benzene or toluene with methyl bromide or ethyl bromide with gallium bromide as catalyst is first-order in each reactant and in catalyst. With aluminum bromide as catalyst, the rate of reaction changes with time, apparently because of heterogeneity of the reaction mixture. The initial rate data fit the kinetic expression ... 

Many di- and poly-alkylated benzenes have been prepared by the Friedel-Crafts reaction. Alkyl groups on the nucleus do not exert a strong directive influence upon the orientation, nor do they greatly affect the rate of further alkylation. The composition of the alkylated product varies widely, depending upon the conditions of the reaction. Appreciable quantities of m-dialkylated and sywz-trialkylated products are obtained under vigorous conditions. The composition of many products is in doubt, as has been shown by later, more accurate analyses. Methylation of xylene gives 1,2,4,5-tetramethylbenzene (durene), pentamethylbenzene, and hexamethylbenzene. ... 

All three target molecules in this problem have more than six carbons, so all answers will include carbon-carbon-bond-forming reactions. So far, there are three types of reactions that form carbon-carbon bonds the Grignard reaction, S 2 substitution by an acetylide ion, and the Friedel-Crafts reactions (alkylation and acylation) on benzene. 

Friedel-Craft reactions Alkylation tiiul alkanoylation (acylation) of benzene— electrophilic aroinalie substitutions. 

Friedel-Crafts reactions. Alkylation of arenes with benzylic and allylic alcohols is achieved with Sc(OT03 as catalyst. An interesting variant is the reductive benzylation using arenecarbaldehydes and l,3-propanediol. The diol serves as a reductant. 

Certain compounds (electrophilic) can react with phenols (nucleophilic). The nucleophilic activity can be either in the iaromatic ring or the oxygen in the hydroxyl group. Examples of electrophilic aromatic substitution include nitration, halogenation, Friedel-Crafts reactions (alkylation and acylation), and sulfonation. The halogenation example shown below is a polysubstitution reaction involving bromine. The polysubstitution usually occurs when polar solvents are used. 

In a similar reaction, called the Friedel-Crafts reaction, alkyl groups can be substituted onto an aromatic ring by reacting an alkyl halide with an aromatic compound in the presence of AICI3 as a catalyst ... 

As another example, consider what happens if we try to perform a Friedel-Crafts reaction (alkylation or acylation) using anihne as a starting material. 

In a Friedel-Crafts reaction, alkyl halides react with benzene in the presence of aluminum chloride to give an alkylbenzene. It is one of the most useful synthetic methods in organic chemistry. 

Intermediates are produced by a variety of reactions. Aromatic hydrocarbons undergo four electrophilic substitution reactions— the Friedel-Crafts reaction (alkylation and acylation), halogenation, nitration, and sul-fonation—as well as oxidation and reduction. These reactions lead to substituted hydrocarbons that can be further reacted to provide intermediates for dyes. The number of dye intermediates actually or potentially available is very large, and the technology of their manufacture is an important part of industrial organic chemistry. Intermediates are used not only for dye manufacture but also for the manufacture of other important products such as pharmaceuticals. 

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