The Minisci-Reaction is a named reaction in organic chemistry

Organic chemistry

Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, composition, reactions, and preparation of carbon-based compounds, hydrocarbons, and their derivatives...

. It is a radical substitution

Radical substitution

In organic chemistry, a radical substitution reaction is a substitution reaction involving free radicals as a reactive intermediate.The reaction always involves at least two steps, and possibly a third....

 to an aromatic compound, in particular to a heteroaromatic base, that introduces an alkyl group. The reaction was published about in 1971 by F. Minisci.. The aromatic compound is generally electron-deficient and with N-aromatic compounds the nitrogen atom is protonated . A typical reaction is that between pyridine

Pyridine

Pyridine is a basic heterocyclic organic compound with the chemical formula C5H5N. It is structurally related to benzene, with one C-H group replaced by a nitrogen atom...

 and pivalic acid

Pivalic acid

Pivalic acid is a carboxylic acid with a molecular formula of 3CCO2H. This colourless, odiferous organic compound is solid at room temperature.-Industrial route:...

 to 2-tert-butylpyridine with silver nitrate

Silver nitrate

Silver nitrate is an inorganic compound with chemical formula . This compound is a versatile precursor to many other silver compounds, such as those used in photography. It is far less sensitive to light than the halides...

, sulfuric acid

Sulfuric acid

Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...

 and ammonium persulfate

Ammonium persulfate

Ammonium persulfate 2S2O8 is a strong oxidizing agent. It is very soluble in water; the dissolution of the salt in water is endothermic. It is a radical initiator. It is used to etch copper on printed circuit boards as an alternative to ferric chloride solution...

. The reaction resembles Friedel-Crafts alkylation but with opposite reactivity and selectivity.

The Minisci reaction proceeds regioselective and enables the introduction of a wide range of alkyl groups. A side-reaction is acylation

Acylation

In chemistry, acylation is the process of adding an acyl group to a compound. The compound providing the acyl group is called the acylating agent....

. The ratio between alkylation and acylation depends on the substrate and the reaction conditions. Due to the simple raw materials and the simple reaction conditions the reaction has many applications in heterocyclic chemistry.

Mechanism

A free radical is formed from the carboxylic acid

Carboxylic acid

Carboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...

 in an oxidative decarboxylation

Oxidative decarboxylation

Pyruvate decarboxylation is the far from equilibrium biochemical reaction that uses pyruvate to form acetyl-CoA, releasing NADH, a reducing equivalent, and carbon dioxide via decarboxylation...

 with silver

Silver

Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...

 salts and a oxidizing agent. The oxidizing angent reoxidizes the silver salt. The radical then reacts with the aromatic compound. The ultimate product is formed by rearomatisation. The acylated product is formed from the acyl radical.