sec-Butyllithium solution

sec-Butyllithium Solution (C₄H₉Li Solution)Overview:

sec-Butyllithium solution (sec-BuLi) is an organolithium reagent used widely in organic synthesis for its strong nucleophilic and basic properties. It is typically available as a solution in hydrocarbons such as hexane, pentane, or toluene. Like other organolithium compounds, sec-Butyllithium is highly reactive and must be handled under an inert atmosphere (usually nitrogen or argon) to prevent decomposition by reaction with moisture or air.

Key Characteristics of sec-Butyllithium Solution:

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  Chemical Formula: C₄H₉Li

  
  


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  Molecular Weight: 54.06 g/mol

  
  


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  Appearance: Typically colorless or light yellow solution (the color may vary depending on concentration and solvent)

  
  


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  Solubility: Soluble in nonpolar solvents such as hexane, pentane, and toluene; insoluble in water and polar solvents

  
  


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  Boiling Point: The boiling point depends on the solvent used (e.g., in hexane it boils at ~68°C)

  
  


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  Reactivity: sec-Butyllithium is highly reactive with moisture, carbon dioxide (CO₂), and oxygen. It reacts vigorously with water to produce butane and lithium hydroxide, making it important to keep it away from water or humid air.

  
  

Physical Properties:

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  Basicity and Nucleophilicity: sec-Butyllithium is a very strong base and nucleophile, which makes it ideal for a wide range of organic reactions. It can deprotonate weak acids and can also initiate polymerization reactions.

  
  


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  Reactivity with Water: sec-Butyllithium reacts violently with water, releasing heat and hydrogen gas:

  
  $$\text{C₄H₉Li}+\text{H₂O}\to \text{C₄H₁₀}+\text{LiOH}$$


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  Air Sensitivity: sec-Butyllithium is also sensitive to oxygen and should be handled under an inert atmosphere to prevent decomposition or unwanted side reactions with oxygen.

  
  

Preparation of sec-Butyllithium Solution:

sec-Butyllithium is typically prepared by reacting sec-butyl chloride (C₄H₉Cl) with lithium metal in a nonpolar solvent (usually hexane or pentane). The reaction proceeds as follows:

$$\text{C₄H₉Cl}+\text{Li}\to \text{C₄H₉Li}+\text{LiCl}$$

The resulting sec-Butyllithium solution is then typically standardized for its concentration and can be stored under an inert atmosphere in sealed containers.

Applications of sec-Butyllithium Solution:

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   Grignard Reagent Analog:

   
   
   
   
   
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     Like other organolithium reagents, sec-Butyllithium is a strong base and nucleophile, often used as an alternative to Grignard reagents in many organic reactions. It can be used in the formation of carbon-carbon bonds through nucleophilic substitution or addition reactions.

     
     
   
   
   
   


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   Synthesis of Organometallic Compounds:

   
   
   
   
   
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     sec-Butyllithium is commonly used to prepare other organometallic compounds such as lithium enolates, alkyl lithium compounds, and other intermediates in organic synthesis.

     
     
   
   
   
   


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   Deprotonation of Weak Acids:

   
   
   
   
   
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     Due to its strong basicity, sec-Butyllithium is used to deprotonate weak acids, including alcohols, thiols, and amines, to generate the corresponding conjugate bases. This is useful in a variety of synthetic transformations.

     
     
   
   
   
   


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   Formation of Carbanions:

   
   
   
   
   
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     sec-Butyllithium can be used to generate sec-butyl carbanions, which are useful intermediates in many reactions, including nucleophilic substitution, addition to carbonyl compounds, and other synthetic pathways.

     
     
   
   
   
   


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   Polymerization Initiator:

   
   
   
   
   
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     sec-Butyllithium is used as an initiator in the polymerization of certain monomers, such as styrene or isoprene, in the production of synthetic rubbers and other polymers.

     
     
   
   
   
   


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   Cross-Coupling Reactions:

   
   
   
   
   
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     sec-Butyllithium Solution is also used in cross-coupling reactions, such as the formation of biaryl compounds, where it reacts with aryl halides in the presence of transition metal catalysts.

     
     
   
   
   
   

Safety and Handling:

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  Highly Reactive: sec-Butyllithium Solution is extremely reactive with water and should be handled under an inert atmosphere (e.g., nitrogen or argon) to prevent reactions with moisture in the air. When exposed to water, it releases hydrogen gas and heat, which can lead to dangerous fires or explosions.

  
  


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  Toxicity: sec-Butyllithium Solution is toxic and can cause severe irritation to the skin, eyes, and mucous membranes. If exposed, it can cause burns and should be treated immediately by washing the affected area with plenty of water.

  
  


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  Flammability: The solution is highly flammable and should be kept away from heat sources, flames, or sparks. All operations should be conducted in a well-ventilated fume hood.

  
  


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  Protective Gear: Always wear protective gloves, goggles, and a lab coat when handling sec-Butyllithium. Work in a fume hood to avoid inhaling fumes or vapors, and ensure proper ventilation.

  
  


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  Inhalation or Skin Contact:

  
  
  
  
  
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    Skin Contact: If sec-Butyllithium comes into contact with the skin, remove contaminated clothing and wash the skin with plenty of water. Seek immediate medical attention.

    
    
  
  
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    Eye Contact: Flush eyes with water for at least 15 minutes and seek medical attention immediately.

    
    
  
  
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    Inhalation: Move to fresh air immediately. Seek medical attention if breathing difficulties occur.

    
    
  
  
  
  


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  Storage: sec-Butyllithium Solution should be stored in tightly sealed containers under an inert atmosphere, away from water, air, and sources of ignition. It should be stored in cool, dry places and away from incompatible materials such as acids, alcohols, or oxidizing agents.

  
  

Where to Buy sec-Butyllithium Solution:

sec-Butyllithium Solution is available from several chemical suppliers, including:

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  Sigma-Aldrich (Merck)

  
  


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  Fisher Scientific

  
  


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  VWR

  
  


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  Alfa Aesar

  
  


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  TCI Chemicals

  
  

These suppliers offer sec-Butyllithium solutions in various concentrations and solvents, such as hexane, pentane, or toluene. It’s important to verify the concentration and solvent compatibility with your specific application.

Environmental Impact:

sec-Butyllithium Solution should not be released into the environment, as it can react violently with water or moisture in the air. It must be disposed of according to local hazardous waste disposal guidelines. The containers should be properly sealed to prevent leaks or contamination.

Conclusion:

sec-Butyllithium Solution is an important organolithium reagent used extensively in organic synthesis for reactions involving the formation of carbon-carbon bonds, deprotonation of weak acids, and polymerization processes. While it is an incredibly valuable tool in the laboratory, it is highly reactive and dangerous to handle, requiring strict safety measures to prevent accidents.

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