The Lemieux–Johnson or Malaprade–Lemieux–Johnson oxidation is a

chemical reaction A chemical reaction is a process that leads to the chemistry, chemical transformation of one set of chemical substances to another. When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an Gibbs free energy, ...

in which an

olefin 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 α-olefins. The International Union of Pu ...

undergoes oxidative cleavage to form two

aldehyde In organic chemistry, an aldehyde () (lat. ''al''cohol ''dehyd''rogenatum, dehydrogenated alcohol) is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred ...

ketone In organic chemistry, a ketone is an organic compound with the structure , where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond C=O). The simplest ketone is acetone ( ...

units. The reaction is named after its inventors, Raymond Urgel Lemieux and

William Summer Johnson William Summer Johnson (February 24, 1913 – August 19, 1995) was an American chemist and teacher. From 1940 to 1958, Johnson was an instructor and then professor at the University of Wisconsin–Madison. In 1958, he moved to Stanford Universi ...

, who published it in 1956. The reaction proceeds in a two step manner, beginning with

dihydroxylation Dihydroxylation is the process by which an alkene is converted into a vicinal (chemistry), vicinal diol. Although there are many routes to accomplish this oxidation, the most common and direct processes use a high-oxidation-state transition metal ...

of the alkene by

osmium tetroxide Osmium tetroxide (also osmium(VIII) oxide) is the chemical compound with the formula OsO4. The compound is noteworthy for its many uses, despite its toxicity and the rarity of osmium. It also has a number of unusual properties, one being that the ...

, followed by a Malaprade reaction to cleave the diol using

periodate Periodate ( ) is an anion composed of iodine and oxygen. It is one of a number of oxyanions of iodine and is the highest in the series, with iodine existing in oxidation state +7. Unlike other perhalogenates, such as perchlorate, it can exist in ...

. Periodate also serves to regenerate the osmium tetroxide. This means only a

catalytic Catalysis () is the increase in reaction rate, rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst ...

amount of the osmium reagent is needed and also that the two consecutive reactions can be performed as a single tandem reaction process. The Lemieux–Johnson reaction ceases at the aldehyde stage of oxidation and therefore produces the same results as

ozonolysis In organic chemistry, ozonolysis is an organic reaction where the Saturated and unsaturated compounds, unsaturated bonds are Bond cleavage, cleaved with ozone (). Multiple carbon–carbon bond are replaced by carbonyl () groups, such as aldehydes ...

. : The classical Lemieux–Johnson oxidation often generates many side products, resulting in low reaction yields; however the addition of non-nucleophilic bases, such as

2,6-lutidine 2,6-Lutidine is a natural heterocyclic aromatic organic compound with the formula (CH3)2C5H3N. It is one of several dimethyl-substituted derivative of pyridine, all of which are referred to as Lutidine, lutidines. It is a colorless liquid with mi ...

, can improve on this. OsO₄ may be replaced with a number of other Osmium compounds. Periodate may also be replaced with other oxidising agents, such as

oxone Potassium peroxymonosulfate is widely used as an oxidizing agent, for example, in pools and spas (usually referred to as monopersulfate or "MPS"). It is the potassium salt of peroxymonosulfuric acid. Potassium peroxymonosulfate per se is rarely e ...

History

The development of the Lemieux–Johnson oxidation was preceded by an analogous process, developed by Lemieux and Ernst Von Rudloff (sometimes called the Lemieux-Von Rudloff reaction), which used an aqueous solution of

sodium periodate Sodium periodate is an inorganic salt, composed of a sodium cation and the periodate anion. It may also be regarded as the sodium salt of periodic acid. Like many periodates, it can exist in two different forms: sodium ''meta''periodate (formula‍ ...

with a low (catalytic) concentration of

potassium permanganate Potassium permanganate is an inorganic compound with the chemical formula KMnO4. It is a purplish-black crystalline salt, which dissolves in water as K+ and ions to give an intensely pink to purple solution. Potassium permanganate is widely us ...

. This mixture became known as Lemieux reagent and has been used to determine the position of double bonds and for preparing carbonyl compounds. Unlike the Lemieux–Johnson oxidation, which normally stops at the aldehyde, this older method could continue to give a mixture of aldehydes and carboxylic acids.

References

{{DEFAULTSORT:Lemieux-Johnson oxidation Organic oxidation reactions Carbohydrate chemistry Name reactions

History

See also

References