Criegee rearrangement: Difference between revisions

Latest revision as of 06:11, 16 February 2025

Overview[edit]

The Criegee rearrangement is a chemical reaction that involves the rearrangement of an ozonide to form a carbonyl compound and a carbonyl oxide. This reaction is named after the German chemist Rudolf Criegee, who first described the mechanism in the mid-20th century. The Criegee rearrangement is a key step in the ozonolysis of alkenes, a process widely used in organic synthesis to cleave carbon-carbon double bonds.

Mechanism[edit]

The Criegee rearrangement occurs during the decomposition of the primary ozonide, also known as the molozonide, which is formed when an alkene reacts with ozone. The molozonide is unstable and undergoes a rearrangement to form a more stable ozonide. This ozonide can then decompose to yield a carbonyl compound and a carbonyl oxide, the latter of which is often referred to as a Criegee intermediate.

The mechanism involves a 1,3-dipolar cycloaddition of ozone to the alkene, forming the molozonide. The molozonide then undergoes a concerted rearrangement, breaking the weak O-O bond and forming the ozonide. The ozonide can further decompose, often in the presence of a reducing agent, to yield the final products.

Applications[edit]

The Criegee rearrangement is an important reaction in synthetic organic chemistry. It is used to cleave alkenes into smaller carbonyl-containing fragments, which can be further manipulated in various synthetic pathways. This reaction is particularly useful in the synthesis of aldehydes and ketones from alkenes.

In addition to its applications in synthesis, the Criegee rearrangement is also of interest in atmospheric chemistry. Criegee intermediates are believed to play a role in the formation of secondary organic aerosols and in the oxidation of atmospheric pollutants.

Related pages[edit]

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-'''Criegee Rearrangement''' is a significant [[organic chemistry]] reaction that involves the ozonolysis of alkenes to form carbonyl compounds. This reaction is named after the German chemist Rudolf Criegee, who first proposed the mechanism in the 20th century. The Criegee rearrangement plays a crucial role in the understanding of ozonolysis and has applications in the synthesis of various organic compounds, including ketones, aldehydes, and carboxylic acids.
+{{DISPLAYTITLE:Criegee Rearrangement}}
-==Mechanism==
+== Overview ==
-The Criegee rearrangement involves several key steps. Initially, the reaction of ozone with an alkene forms a molozonide, which is an unstable intermediate. This molozonide then undergoes a rearrangement to form a more stable ozonide. The critical step in the Criegee mechanism is the cleavage of the ozonide by a reductive or oxidative workup, leading to the formation of carbonyl compounds. Depending on the conditions and the workup procedure, different products can be obtained from the same ozonide intermediate.
+The '''Criegee rearrangement''' is a chemical reaction that involves the rearrangement of an [[ozonide]] to form a [[carbonyl compound]] and a [[carbonyl oxide]]. This reaction is named after the German chemist [[Rudolf Criegee]], who first described the mechanism in the mid-20th century. The Criegee rearrangement is a key step in the [[ozonolysis]] of [[alkenes]], a process widely used in organic synthesis to cleave carbon-carbon double bonds.
-==Applications==
+== Mechanism ==
-The Criegee rearrangement has found applications in various fields of organic synthesis. It is particularly useful in the synthesis of complex molecules from simpler alkenes, making it a valuable tool in pharmaceutical research and the production of fine chemicals. Additionally, the reaction's ability to cleave double bonds selectively makes it an essential technique for the structural elucidation of natural products.
+The Criegee rearrangement occurs during the decomposition of the primary ozonide, also known as the molozonide, which is formed when an alkene reacts with [[ozone]]. The molozonide is unstable and undergoes a rearrangement to form a more stable [[ozonide]]. This ozonide can then decompose to yield a carbonyl compound and a carbonyl oxide, the latter of which is often referred to as a [[Criegee intermediate]].
-==Environmental Significance==
+[[File:Criegee_rearrangement.png|thumb|right|Diagram of the Criegee rearrangement mechanism.]]
-Beyond its applications in organic synthesis, the Criegee rearrangement also has environmental implications. Criegee intermediates are involved in the atmospheric reactions of ozone with alkenes, leading to the formation of secondary organic aerosols. These aerosols play a significant role in atmospheric chemistry and climate, affecting air quality and health.
-==See Also==
+The mechanism involves a 1,3-dipolar cycloaddition of ozone to the alkene, forming the molozonide. The molozonide then undergoes a concerted rearrangement, breaking the weak O-O bond and forming the ozonide. The ozonide can further decompose, often in the presence of a reducing agent, to yield the final products.
+== Applications ==
+The Criegee rearrangement is an important reaction in synthetic organic chemistry. It is used to cleave alkenes into smaller carbonyl-containing fragments, which can be further manipulated in various synthetic pathways. This reaction is particularly useful in the synthesis of [[aldehydes]] and [[ketones]] from alkenes.
+In addition to its applications in synthesis, the Criegee rearrangement is also of interest in atmospheric chemistry. Criegee intermediates are believed to play a role in the formation of secondary organic aerosols and in the oxidation of atmospheric pollutants.
+== Related pages ==
 * [[Ozonolysis]]
-* [[Organic synthesis]]
+* [[Rudolf Criegee]]
-* [[Carbonyl compounds]]
+* [[Carbonyl compound]]
-* [[Atmospheric chemistry]]
+* [[Alkene]]
+* [[Ozone]]
-==References==
-<references/>
 [[Category:Organic reactions]]
-[[Category:Chemical reactions]]
+[[Category:Rearrangement reactions]]
-{{Chemistry-stub}}