Disproportionation Reaction


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Disproportionation Reaction

 

the redistribution of atoms or their groups among molecules of the same substance, as a result of which the substance becomes two or more different substances, some of which have more—and others fewer—of those atoms or groups than the original substance. Most disproportionation reactions are oxidation-reduction processes and are associated with the redistribution of atoms of oxygen or hydrogen. For example, upon heating, mercurous oxide yields mercury and mercuric oxide:

In the presence of alkalies, aldehydes yield the corresponding alcohols and carboxylic acids (the Cannizzaro reaction):

Irreversible Zelinskii catalysis belongs to the same type of disproportionation reaction:

as does the conversion of free alkyl radicals into alkenes and alkanes:

2CH3–CH2 CH2=CH2 + Ch3–CH3

An example of a disproportionation reaction that is accompanied by redistribution of alkyl groups is the conversion of alkyl benzenes into a mixture of benzene and polyalkyl benzenes when treated with aluminum chloride:

The disproportionation reaction is extensively used in chemistry and often has great preparative significance.

B. L. DIATKIN

References in periodicals archive ?
Based on the results of microstructure and kinetic analysis above, some useful insights can be obtained into the mechanism of hydrogen sorption reaction and disproportionation reaction for ball milled [Zr.sub.0.8][Ti.sub.0.2]Co samples.
The generated free radicals caused disproportionation reaction to produce saturation and unsaturation monoester.
One problem that arose during analysis was that this compound and its derivatives undergo a phenomenon that appears to be a disproportionation reaction. The purpose of this research was to find a way to stop this disproportionation reaction from occurring without altering the catalytic properties of the compound and its derivatives.
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where [M.sub.mono] denotes the molecular weight of monomer, and [k.sub.t]" the rate constant for the disproportionation reaction.
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This enzyme catalyzes disproportionation reactions, which hydrolyze [alpha]-glycosidic linkage and subsequently synthesize new [alpha]-glycosidic linkage within the same or different glucan molecules [7, 8].
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