Kolbe–Schmitt reaction: Difference between revisions

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'''Kolbe–Schmitt reaction''' or '''Kolbe process''' is a carboxylation chemical reaction that synthesizes salicylic acid and its derivatives. This reaction is named after the German chemists Hermann Kolbe and Rudolf Schmitt who developed the process in 1885. The Kolbe–Schmitt reaction proceeds by the nucleophilic addition of carbon dioxide to a phenoxide, which is formed from the deprotonation of a phenol. The reaction is significant in both organic chemistry and the pharmaceutical industry, particularly in the production of aspirin and other salicylate drugs.
{{Short description|A chemical reaction used to synthesize salicylic acid}}


==Reaction Mechanism==
== Kolbe–Schmitt reaction ==
The Kolbe–Schmitt reaction begins with the treatment of a phenol with a strong base, typically potassium hydroxide (KOH), resulting in the formation of a potassium phenoxide. This phenoxide then reacts with carbon dioxide under high pressure and temperature to form a potassium salicylate. Acidification of the potassium salicylate yields salicylic acid, a key precursor in the synthesis of aspirin and other pharmaceuticals.
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 general reaction can be represented as follows:
[[File:Kolbe-Schmitt-reaction-mechanism.png|thumb|right|300px|Mechanism of the Kolbe–Schmitt reaction]]


Phenol + CO2 (high pressure, high temperature) → Salicylic acid
== Mechanism ==
The Kolbe–Schmitt reaction proceeds through the following steps:


==Applications==
# '''Formation of the phenolate ion''': The reaction begins with the deprotonation of a [[phenol]] to form a [[phenolate ion]]. This is typically achieved by treating the phenol with a strong [[base]] such as [[sodium hydroxide]] (NaOH).
The primary application of the Kolbe–Schmitt reaction is in the pharmaceutical industry for the production of salicylic acid and its derivatives. Salicylic acid is a precursor to aspirin (acetylsalicylic acid), one of the most widely used medications for pain relief, fever reduction, and anti-inflammatory purposes. Additionally, salicylic acid derivatives produced through this reaction are used in the manufacture of dyes, fragrances, and preservatives.
# '''Carboxylation''': The phenolate ion is then reacted with [[carbon dioxide]] (CO₂) under high pressure and elevated temperature. This step results in the formation of a [[carboxylate]] intermediate.
# '''Protonation''': The carboxylate intermediate is then protonated to yield the final product, which is a [[salicylic acid]] derivative.


==Advantages and Limitations==
The overall reaction can be summarized as follows:
One of the main advantages of the Kolbe–Schmitt reaction is its straightforward mechanism, which allows for the efficient production of salicylic acid and its derivatives. However, the reaction conditions—high pressure and temperature—can be considered a limitation as they require specialized equipment and can increase production costs. Furthermore, the reaction's specificity to phenols limits its applicability to a narrower range of substrates.


==Environmental Considerations==
: C₆H₅ONa + CO₂ + H₂O → C₆H₄(OH)COOH + NaOH
The environmental impact of the Kolbe–Schmitt reaction is a topic of ongoing research. While the reaction itself does not produce significant toxic byproducts, the use of high pressure and temperature conditions raises concerns regarding energy consumption and the carbon footprint of the process. Efforts to develop more sustainable versions of the Kolbe–Schmitt reaction are focused on lowering the reaction conditions and finding greener alternatives for the reagents used.


==See Also==
== Applications ==
The Kolbe–Schmitt reaction is primarily used 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.
 
== Historical significance ==
The development of the Kolbe–Schmitt reaction marked a significant advancement in the field of organic synthesis. It provided a practical method for the large-scale production of salicylic acid, which was previously difficult to synthesize efficiently. This reaction laid the groundwork for the development of [[non-steroidal anti-inflammatory drugs]] (NSAIDs) and other important medicinal compounds.
 
[[File:K_S_startAnimGif.gif|thumb|left|300px|Animation of the Kolbe–Schmitt reaction]]
 
== Related pages ==
* [[Salicylic acid]]
* [[Aspirin]]
* [[Aspirin]]
* [[Salicylic acid]]
* [[Carboxylation]]
* [[Phenol]]
* [[Phenol]]
* [[Carboxylation]]
* [[Hermann Kolbe]]
* [[Organic synthesis]]
* [[Rudolf Schmitt]]


[[Category:Organic reactions]]
[[Category:Organic reactions]]
[[Category:Chemical processes]]
[[Category:Carbon-carbon bond forming reactions]]
[[Category:Name reactions]]
[[Category:Name reactions]]
{{Chemistry-stub}}
<gallery>
Kolbe–Schmitt_reaction
File:Kolbe-Schmitt-reaction-mechanism.png|Mechanism of the Kolbe–Schmitt reaction
File:K_S_startAnimGif.gif|Animation of the Kolbe–Schmitt reaction
</gallery>

Latest revision as of 14:13, 21 February 2025

A chemical reaction used to synthesize salicylic acid


Kolbe–Schmitt reaction[edit]

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 of the Kolbe–Schmitt reaction

Mechanism[edit]

The Kolbe–Schmitt reaction proceeds through the following steps:

  1. Formation of the phenolate ion: The reaction begins with the deprotonation of a phenol to form a phenolate ion. This is typically achieved by treating the phenol with a strong base such as sodium hydroxide (NaOH).
  2. Carboxylation: The phenolate ion is then reacted with carbon dioxide (CO₂) under high pressure and elevated temperature. This step results in the formation of a carboxylate intermediate.
  3. Protonation: The carboxylate intermediate is then protonated to yield the final product, which is a salicylic acid derivative.

The overall reaction can be summarized as follows:

C₆H₅ONa + CO₂ + H₂O → C₆H₄(OH)COOH + NaOH

Applications[edit]

The Kolbe–Schmitt reaction is primarily used 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.

Historical significance[edit]

The development of the Kolbe–Schmitt reaction marked a significant advancement in the field of organic synthesis. It provided a practical method for the large-scale production of salicylic acid, which was previously difficult to synthesize efficiently. This reaction laid the groundwork for the development of non-steroidal anti-inflammatory drugs (NSAIDs) and other important medicinal compounds.

Animation of the Kolbe–Schmitt reaction

Related pages[edit]