Kolbe–Schmitt reaction: Difference between revisions
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{{Short description|A chemical reaction used in organic chemistry}} | |||
{{Use dmy dates|date=October 2023}} | |||
The '''Kolbe–Schmitt reaction''' is an important [[chemical reaction]] in [[organic chemistry]] that involves the carboxylation of [[phenolates]] to produce [[salicylic acid]] derivatives. This reaction is named after the chemists [[Hermann Kolbe]] and [[Rudolf Schmitt]], who developed the process in the late 19th century. | |||
The Kolbe–Schmitt reaction | |||
The general | ==Mechanism== | ||
The Kolbe–Schmitt reaction proceeds through the reaction of a [[sodium phenoxide]] with [[carbon dioxide]] under high pressure and temperature conditions. The general mechanism involves the following steps: | |||
Phenol | # '''Formation of Sodium Phenoxide''': [[Phenol]] is treated with [[sodium hydroxide]] to form sodium phenoxide. | ||
# '''Carboxylation''': The sodium phenoxide is then exposed to carbon dioxide gas at elevated temperatures (around 125–150 °C) and pressures (approximately 100 atm). This results in the formation of an [[ortho-carboxylate]] intermediate. | |||
# '''Acidification''': The reaction mixture is acidified, typically with [[sulfuric acid]], to yield the desired [[salicylic acid]]. | |||
[[File:Kolbe-Schmitt reaction mechanism.png|thumb|right|300px|Mechanism of the Kolbe–Schmitt reaction.]] | |||
==Applications== | ==Applications== | ||
The primary application of the Kolbe–Schmitt reaction is in the | The primary application of the Kolbe–Schmitt reaction is in the industrial production of [[salicylic acid]], which is a precursor to [[aspirin]] and other pharmaceuticals. Salicylic acid is also used in the manufacture of dyes, preservatives, and as a [[keratolytic]] agent in dermatology. | ||
==Advantages and Limitations== | ==Advantages and Limitations== | ||
The Kolbe–Schmitt reaction is advantageous due to its ability to selectively carboxylate phenolates at the ortho position. However, the reaction requires harsh conditions, including high temperatures and pressures, which can limit its applicability in some contexts. Additionally, the reaction is specific to phenolates and does not work well with other types of [[aromatic compounds]]. | |||
== | ==Historical Context== | ||
The | The development of the Kolbe–Schmitt reaction marked a significant advancement in the field of organic synthesis. Hermann Kolbe first discovered the reaction in 1860, and it was later refined by Rudolf Schmitt in 1885. This reaction laid the groundwork for the synthesis of many important [[aromatic carboxylic acids]]. | ||
== | ==Related pages== | ||
* [[Salicylic acid]] | |||
* [[Aspirin]] | * [[Aspirin]] | ||
* [[ | * [[Carboxylation]] | ||
* [[Phenol]] | * [[Phenol]] | ||
* [[Organic chemistry]] | |||
* [[Organic | |||
[[Category:Organic reactions]] | [[Category:Organic reactions]] | ||
[[Category: | [[Category:Carbon dioxide]] | ||
[[Category: | [[Category:Carboxylation reactions]] | ||
Revision as of 17:43, 18 February 2025
A chemical reaction used in organic chemistry
The Kolbe–Schmitt reaction is an important chemical reaction in organic chemistry that involves the carboxylation of phenolates to produce salicylic acid derivatives. This reaction is named after the chemists Hermann Kolbe and Rudolf Schmitt, who developed the process in the late 19th century.
Mechanism
The Kolbe–Schmitt reaction proceeds through the reaction of a sodium phenoxide with carbon dioxide under high pressure and temperature conditions. The general mechanism involves the following steps:
- Formation of Sodium Phenoxide: Phenol is treated with sodium hydroxide to form sodium phenoxide.
- Carboxylation: The sodium phenoxide is then exposed to carbon dioxide gas at elevated temperatures (around 125–150 °C) and pressures (approximately 100 atm). This results in the formation of an ortho-carboxylate intermediate.
- Acidification: The reaction mixture is acidified, typically with sulfuric acid, to yield the desired salicylic acid.
Applications
The primary application of the Kolbe–Schmitt reaction is in the industrial production of salicylic acid, which is a precursor to aspirin and other pharmaceuticals. Salicylic acid is also used in the manufacture of dyes, preservatives, and as a keratolytic agent in dermatology.
Advantages and Limitations
The Kolbe–Schmitt reaction is advantageous due to its ability to selectively carboxylate phenolates at the ortho position. However, the reaction requires harsh conditions, including high temperatures and pressures, which can limit its applicability in some contexts. Additionally, the reaction is specific to phenolates and does not work well with other types of aromatic compounds.
Historical Context
The development of the Kolbe–Schmitt reaction marked a significant advancement in the field of organic synthesis. Hermann Kolbe first discovered the reaction in 1860, and it was later refined by Rudolf Schmitt in 1885. This reaction laid the groundwork for the synthesis of many important aromatic carboxylic acids.
