In chemistry, redistribution usually refers to the exchange of anionic ligands bonded to metal and metalloid centers. The conversion does not involve

redox Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate (chemistry), substrate change. Oxidation is the loss of Electron, electrons or an increase in the oxidation state, while reduction ...

, in contrast to

disproportionation In chemistry, disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation states. More generally, the term ca ...

reactions. Some useful redistribution reactions are conducted at higher temperatures; upon cooling the mixture, the product mixture is kinetically frozen and the individual products can be separated. In cases where redistribution is rapid at mild temperatures, the reaction is less useful synthetically but still important mechanistically.

Examples

Rapid redistribution reactions are exhibited by methylboranes. Thus monomethyldiborane rapidly converts at room temperature to

diborane Diborane(6), generally known as diborane, is the chemical compound with the formula B2H6. It is a toxic, colorless, and pyrophoric gas with a repulsively sweet odor. Diborane is a key boron compound with a variety of applications. It has attracte ...

and trimethylborane:. The authors refer to redistributions as "disproportionations". :6 MeB₂H₅ → 5 B₂H₆ + 2 Me₃B Useful redistribution reactions are found in organoaluminium, organoboron, and organosilicon chemistry. : BCl₃ + 2 B(C₂H₅)₃ → 3 BCl(C₂H₅)₂ In another example,

tetramethylsilane Tetramethylsilane (abbreviated as TMS) is the organosilicon compound with the formula Si(CH3)4. It is the simplest tetraorganosilane. Like all silanes, the TMS framework is tetrahedral. TMS is a building block in organometallic chemistry but also ...

is an undesirable product of the industrially important

direct process The direct process, also called the direct synthesis, Rochow process, and Müller-Rochow process is the most common technology for preparing organosilicon compounds on an industrial scale. It was first reported independently by Eugene G. Rochow and ...

, but it can be converted (recycled) into more useful products by redistribution with

silicon tetrachloride Silicon tetrachloride or tetrachlorosilane is the inorganic compound with the formula SiCl4. It is a colourless volatile liquid that fumes in air. It is used to produce high purity silicon and silica for commercial applications. Preparation Sili ...

: : SiMe₄ + SiCl₄ → 2 SiMe₂Cl₂ In organotin chemistry, the mixed alkyl tin chlorides are produced by redistribution, a reaction called the Kocheshkov comproportionation: : 3 SnBu₄ + SnCl₄ → 4 SnBu₃Cl Many metal

halide In chemistry, a halide (rarely halogenide) is a binary chemical compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative (or more electropositive) than the halogen, to make a f ...

s undergo redistribution reactions, usually to afford nearly statistical mixtures of products. For example,

titanium tetrachloride Titanium tetrachloride is the inorganic compound with the formula . It is an important intermediate in the production of titanium metal and the pigment titanium dioxide. is a volatile liquid. Upon contact with humid air, it forms thick clouds ...

and titanium tetrabromide redistribute their halide ligands, one of many reactions in this conversion is shown: : TiCl₄ + TiBr₄ → 2 TiBr₂Cl₂

References

{{reflist Chemical reactions Chemical processes