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Friedel–Crafts alkylations can be reversible. Although this is usually undesirable it can be exploited; for instance by facilitating transalkylation reactions. [10] 1,3-Diisopropylbenzene is produced via transalkylation, a special form of Friedel–Crafts alkylation. It also allows alkyl chains to be added reversibly as protecting groups.
For example, Friedel–Crafts acylation uses acetyl chloride (CH 3 COCl) as the agent and aluminum chloride (AlCl 3) as a catalyst to add an acetyl group to benzene: [2] Friedel-Crafts acylation of benzene by ethanoyl chloride. This reaction is an example of electrophilic aromatic substitution.
Acetyl chloride was first prepared in 1852 by French chemist Charles Gerhardt by treating potassium acetate with phosphoryl chloride. [4]Acetyl chloride is produced in the laboratory by the reaction of acetic acid with chlorodehydrating agents such as phosphorus trichloride (PCl 3), phosphorus pentachloride (PCl 5), sulfuryl chloride (SO 2 Cl 2), phosgene, or thionyl chloride (SOCl 2).
Oxalyl chloride reacts with aromatic compounds in the presence of aluminium chloride to give the corresponding acyl chloride in a process known as a Friedel-Crafts acylation. [15] [16] The resulting acyl chloride can be hydrolysed to form the corresponding carboxylic acid.
In chemistry, acetylation is an organic esterification reaction with acetic acid. It introduces an acetyl group into a chemical compound. Such compounds are termed acetate esters or simply acetates. Deacetylation is the opposite reaction, the removal of an acetyl group from a chemical compound.
Ferrocene undergoes many reactions characteristic of aromatic compounds, enabling the preparation of substituted derivatives. A common undergraduate experiment is the Friedel–Crafts reaction of ferrocene with acetic anhydride (or acetyl chloride) in the presence of phosphoric acid as a catalyst.
Acylium ions are common reactive intermediates, for example in the Friedel–Crafts acylation and many other organic reactions such as the Hayashi rearrangement. Salts containing acylium ions can be generated by removal of the halide from acyl halides: RC(O)Cl + SbCl 5 → [RCO] + [SbCl 6] −
A native of Strasbourg, France, he was a student of Louis Pasteur at the Sorbonne.In 1876, he became a professor of chemistry and mineralogy at the Sorbonne.. Friedel developed the Friedel-Crafts alkylation and acylation reactions with James Crafts in 1877, [2] [3] and attempted to make synthetic diamonds.