Friedel-Crafts Acylation Alkanoylation

The second electrophilic aromatic substitution that forms carbon-carbon bonds is Friedel-Crafts alkanoylation (as in butanoylation, pentanoylation, and so on). A more popular alternative systematic name for this process is acylation, which is the term we shall use. lUPAC 

Friedel-Crafts acylation employs acyl chlorides 

Benzene reacts with acyl halides in the presence of an aluminum halide to give 1-phenylalkanones (phenyl ketones). An example is the preparation of 1-phenylethanone 

Friedel-Crafts Acylation of Benzene with Acetyl Chloride 

Acyl chlorides are reactive derivatives of carboxylic adds. They are readily formed from carboxylic adds by reaction with thionyl chloride, 8002. (We shall explore this process in detail in Chapto 19.) 

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Purpose. To investigate the conditions under which the synthetically important Friedel-Crafts acylation (alkanoylation) reaction is carried out. The reaction described here illustrates electrophilic aromatic substitution on an aromatic ring... 

More than one approach can be used for both (a) and (b) one based on Friedel-Crafts acylation (acylation), which uses an alkanoyl chloride, and another using Grignard addition to an aldehyde or a ketone. 

In contrast to Friedel-Crafts alkylations, which with longer chain -alkyl halides usually give a substantial proportion of the corresponding secondary alkylarenes, Friedel-Crafts acylation also goes well with longer chain -alkanoyl chlorides (and anhydrides). There are numerous methods for the reduction of the resulting arylketones. Most often used are reductions with LiAlH4/... 

Orientation of the incoming acyl group in Friedel-Crafts acylations can be quite sensitive to the reaction solvent and other procedural variables. In general, however, para attack predominates for alkylbenzenes. The percentage of ortho attack increases with the electrophilicity of the acylium ion and approaches 1 1 with such less selective species as formyl and 2,4-dinitrobenzoyl ions. For simple alkanoyl and benzoyl halides, the o p ratio is usually 1 20 or higher. ... 

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

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