The Hunsdiecker reaction (also called the Borodin reaction after Alexander Borodin

Alexander Borodin

Alexander Porfiryevich Borodin was a Russian Romantic composer and chemist of Georgian–Russian parentage. He was a member of the group of composers called The Five , who were dedicated to producing a specifically Russian kind of art music...

) is the organic reaction

Organic reaction

Organic reactions are chemical reactions involving organic compounds. The basic organic chemistry reaction types are addition reactions, elimination reactions, substitution reactions, pericyclic reactions, rearrangement reactions, photochemical reactions and redox reactions. In organic synthesis,...

 of 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 of 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...

s with halogen

Halogen

The halogens or halogen elements are a series of nonmetal elements from Group 17 IUPAC Style of the periodic table, comprising fluorine , chlorine , bromine , iodine , and astatine...

s to give organic halide

Halide

A halide is a binary compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative than the halogen, to make a fluoride, chloride, bromide, iodide, or astatide compound. Many salts are halides...

s. It is an example of a halogenation

Halogenation

Halogenation is a chemical reaction that incorporates a halogen atom into a molecule in substitution of hydrogen atom. Halogenation takes place in the gas phase. There are four types of halogenation: fluorination, chlorination, bromination, and iodination...

 reaction. The reaction is named after Heinz Hunsdiecker

Heinz Hunsdiecker

Heinz Hunsdiecker was a German chemist who together with his wife Cläre Hunsdiecker improved a reaction of Alexander Borodin now known as the Hunsdiecker reaction.-References:...

 and Cläre Hunsdiecker.

Several reviews have been published.

Mercuric oxide will also effect this transformation.

Reaction mechanism

The reaction mechanism

Reaction mechanism

In chemistry, a reaction mechanism is the step by step sequence of elementary reactions by which overall chemical change occurs.Although only the net chemical change is directly observable for most chemical reactions, experiments can often be designed that suggest the possible sequence of steps in...

 of the Hunsdiecker reaction is believed to involve organic radical

Radical (chemistry)

Radicals are atoms, molecules, or ions with unpaired electrons on an open shell configuration. Free radicals may have positive, negative, or zero charge...

 intermediates. The silver salt of the carboxylic acid 1 will quickly react with bromine to form intermediate 2. Formation of the diradical

Diradical

A diradical in organic chemistry is a molecular species with two electrons occupying two degenerate molecular orbitals . They are known by their higher reactivities and shorter lifetimes. In a broader definition diradicals are even-electron molecules that have one bond less than the number...

 pair 3 allows for radical decarboxylation to form the diradical pair 4, which will quickly recombine to form the desired organic halide 5.

Simonini reaction

The reaction of silver salts of carboxylic acids with iodine

Iodine

Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....

 is called the Simonini reaction , named after Angelo Simonini, a student of Adolf Lieben at the University of Vienna

University of Vienna

The University of Vienna is a public university located in Vienna, Austria. It was founded by Duke Rudolph IV in 1365 and is the oldest university in the German-speaking world...

. The ratio of the reagents play an important role in the determination of products, namely, if 1:1 ratio of salt and iodine is used alkyl iodide is formed. On the other hand, a 2:1 ratio gives RCOOR. and 3:2 ratio gives both the products.