Deoxydehydration (DODH) is a chemical reaction for removing two adjacent
hydroxyl group
In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy ...
s in a
vicinal diol to form an
alkene
In organic chemistry, an alkene, or olefin, is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or at the terminal position. Terminal alkenes are also known as Alpha-olefin, α-olefins.
The Internationa ...
. In contrast to
hydrodeoxygenation which uses hydrogen as a
reductant
In chemistry, a reducing agent (also known as a reductant, reducer, or electron donor) is a chemical species that "donates" an electron to an (called the , , , or ).
Examples of substances that are common reducing agents include hydrogen, carbon ...
, deoxydehydration is able to use a variety of other reductants such as alcohols and organic phosphines. In research, the most common homogeneous catalysts for this reaction use
rhenium
Rhenium is a chemical element; it has symbol Re and atomic number 75. It is a silvery-gray, heavy, third-row transition metal in group 7 of the periodic table. With an estimated average concentration of 1 part per billion (ppb), rhenium is one ...
.
Recently, research has focused on the use of
vanadium
Vanadium is a chemical element; it has Symbol (chemistry), symbol V and atomic number 23. It is a hard, silvery-grey, malleable transition metal. The elemental metal is rarely found in nature, but once isolated artificially, the formation of an ...
heterogeneous catalysts
Heterogeneous catalysis is catalysis where the phase of catalysts differs from that of the reagents or products. The process contrasts with homogeneous catalysis where the reagents, products and catalyst exist in the same phase. Phase distingui ...
for deoxydehydration, such as the conversion of 2,3-butanediol to butene.
Although deoxydehydration over vanadium catalysts requires higher temperatures than over rhenium catalysts, the reaction can proceed without the need for hydrogen or external reductants, which can reduce waste products.
References
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Organic reduction reactions