In chemistry, redistribution usually refers to the exchange of anionic ligands bonded to metal and metalloid centers. The conversion does not involve
redox, in contrast to
disproportionation 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 and
trimethylborane
Trimethylborane (TMB) is a toxic, Pyrophoricity, pyrophoric gas with the formula B(CH3)3 (which can also be written as Me3B, with Me representing methyl).
Properties
As a liquid it is colourless. The strongest line in the infrared spectrum is at ...
:
[. The authors refer to redistributions as "disproportionations".]
:6 MeB
2H
5 → 5 B
2H
6 + 2 Me
3B
Useful redistribution reactions are found in
organoaluminium
Organoaluminium chemistry is the study of compounds containing bonds between carbon and aluminium. It is one of the major themes within organometallic chemistry. Illustrative organoaluminium compounds are the dimer trimethylaluminium, the monomer ...
,
organoboron
Organoborane or organoboron compounds are chemical compounds of boron and carbon that are organic derivatives of BH3, for example trialkyl boranes. Organoboron chemistry or organoborane chemistry is the chemistry of these compounds.
Organoboron ...
, and
organosilicon chemistry.
: BCl
3 + 2 B(C
2H
5)
3 → 3 BCl(C
2H
5)
2
In another example,
tetramethylsilane is an undesirable product of the industrially important
direct process, 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
Silic ...
:
: SiMe
4 + SiCl
4 → 2 SiMe
2Cl
2
In
organotin chemistry
Organotin compounds or stannanes are chemical compounds based on tin with hydrocarbon substituents. Organotin chemistry is part of the wider field of organometallic chemistry. The first organotin compound was diethyltin diiodide (), discovered by ...
, the mixed alkyl tin chlorides are produced by redistribution, a reaction called the Kocheshkov comproportionation:
: 3 SnBu
4 + SnCl
4 → 4 SnBu
3Cl
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 fluor ...
s undergo redistribution reactions, usually to afford nearly statistical mixtures of products. For example,
titanium tetrachloride and
titanium tetrabromide redistribute their halide ligands, one of many reactions in this conversion is shown:
: TiCl
4 + TiBr
4 → 2 TiBr
2Cl
2
References
{{reflist
Chemical reactions
Chemical processes