Friedel-Crafts acylation definition

Here, the term no-solvent means the absence of a traditional solvent—the reactants are neat and may well be sohds. Where one reactant is in sufficiently large excess to qualify as a solvent, for example in Friedel-Crafts alkylations or acylations with excess benzene or toluene, the reactions are not normally classified as no-sol-vent. The phrase solid-phase (solid-state) reaction today often describes a reaction carried out on a solid phase, like a resin, to which the reaction intermediates are bound by adding reagents in solution. These reactions have become very important in combinatorial chemistry, but they do not meet the definition of no-solvent. The nosolvent reactions refer only to the primary reactions themselves and not to workup conditions which may or may not involve solvents (Dittmer, 1997). 

But there is another important type of acid the Lewis acid. These acids don t donate protons—indeed they usually have no protons to donate. Instead they accept electrons. It is indeed a more general definition of acids to say that they accept electrons and of bases that they donate electrons. Lewis acids are usually halides of the higher oxidation states of metals, such as BF3, AICI3, ZnCl2, SbFj, and TiCl4. By removing electrons from organic compounds, Lewis acids act as important catalysts in important reactions such as the Friedel-Crafts alkylation and acylation of benzene (Chapter 21), the S l substitution reaction (Chapter 15), and the Diels-Alder reaction (Chapter 34). 

The Stolle reaction is thought to occur via a typical mechanism for amide formation from an amine and acid chloride, followed by Friedel-Crafts alkylation or acylation. No definitive mechanistic work has been performed on this reaction, but incorporating the mechnistic understandings of two steps provides a firm basis for understanding the mechanism of this reaction. Formation of the mono-amide from oxalyl chloride and aniline provides intermediate 4, which in the presence of AICI3 undergoes intramolecular electrophilic aromatic substitution to the desired 2,3-dioxindole (isatin) 7 via intermediates 5 and 6. 

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