Tempo Free Radical is a stable free radical widely used in organic chemistry for various oxidation reactions and other applications. This guide aims to provide detailed information about TEMPO, including its chemical properties, uses, mechanisms, handling precautions, and more.

What is TEMPO?

TEMPO is a persistent free radical that is an efficient catalyst and reagent in organic synthesis. Its stability and unique properties make it valuable for numerous chemical transformations, particularly in the field of oxidation.

Chemical Properties

• Chemical Formula: C9H18NO
• Molecular Weight: 156.25 g/mol
• Appearance: Orange-red crystalline solid
• Melting Point: 36-38°C
• Solubility: Soluble in organic solvents such as dichloromethane, ethanol, and acetonitrile; sparingly soluble in water.
• Case No: 2564-83-2

Manufacturer

TEMPO is produced by various chemical companies specializing in fine chemicals and laboratory reagents. These manufacturers ensure high purity and quality standards to meet the requirements of research and industrial applications.

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• Triflic Anhydride
• trimethylsilyl trifluoromethanesulfonate
• Sodium Triacetoxyborohydride

Uses of TEMPO

TEMPO is primarily used in:

• Oxidation Reactions: TEMPO is an excellent catalyst for the selective oxidation of alcohols to aldehydes or ketones, and the oxidation of primary alcohols to carboxylic acids.
• Polymer Chemistry: It is used in the controlled radical polymerization (CRP) process and in the modification of polymers.
• Biochemistry: TEMPO derivatives are utilized as spin labels in electron spin resonance (ESR) spectroscopy to study protein structures and dynamics.
• Organic Synthesis: TEMPO is used in various organic transformations, including C-H activation and amination reactions.

How TEMPO Works

TEMPO operates through a free radical mechanism, making it a versatile reagent in oxidative processes. The typical steps in a TEMPO-mediated oxidation reaction include:

1. Activation: TEMPO abstracts a hydrogen atom from the substrate (e.g., an alcohol), generating a radical intermediate.
2. Oxidation: The radical intermediate undergoes further oxidation, often in the presence of a co-oxidant (e.g., bleach or sodium hypochlorite), leading to the formation of the desired product (e.g., an aldehyde or ketone).
3. Catalytic Cycle: TEMPO is regenerated at the end of the reaction cycle, allowing it to be used catalytically in small amounts.

Handling and Storage

Proper handling and storage of TEMPO are crucial to maintaining its stability and effectiveness:

• Storage: Store TEMPO in a cool, dry place, ideally below 25 °C, in a tightly sealed container away from light and moisture.
• Handling: When handling TEMPO, wear appropriate personal protective equipment (PPE), such as gloves and safety goggles. Work in a well-ventilated area or under a fume hood to avoid inhalation and contact.

Precautions

When using TEMPO, consider the following safety precautions:

• Health Hazards: TEMPO can cause skin and eye irritation. Avoid direct contact and inhalation of dust or vapors.
• Chemical Stability: Ensure TEMPO is stored properly to prevent degradation and loss of activity.
• Environmental Safety: Dispose of TEMPO and its byproducts according to local regulations and guidelines for hazardous waste.

Side Effects and Toxicity

• Acute Exposure: May cause irritation to the skin, eyes, and respiratory system. In case of contact, rinse thoroughly with water and seek medical attention if necessary.
• Chronic Exposure: Prolonged exposure may lead to sensitization and allergic reactions in some individuals.

Applications in Research and Industry

• Pharmaceuticals: TEMPO is used in the synthesis of pharmaceutical intermediates and active ingredients.
• Material Science: It is employed in the functionalization of materials and in the preparation of advanced polymers.
• Biochemistry: TEMPO derivatives serve as spin labels for structural and dynamic studies of biomolecules.

FAQ

1. Can TEMPO be used in aqueous solutions?

• TEMPO is sparingly soluble in water but is typically used in organic solvents. Special aqueous-compatible derivatives of TEMPO can be used for reactions in water.

2. How should I dispose of TEMPO?

• Dispose of TEMPO according to local hazardous waste disposal regulations. Consult your institution's safety guidelines for proper disposal methods.

3. What is the shelf life of TEMPO?

• When stored properly, TEMPO has a long shelf life, often several years. Check the manufacturer's specifications for exact details.

4. Can TEMPO be used with other oxidation agents?

• Yes, TEMPO is often used in combination with other co-oxidants like bleach (sodium hypochlorite), sodium chlorite, or iodine to enhance oxidation efficiency.

5. Is TEMPO compatible with all solvents?

• TEMPO is soluble in many organic solvents, including dichloromethane, ethanol, and acetonitrile. Solubility in water is limited, and it should be kept away from light and moisture to prevent degradation.

6. What should I do if TEMPO comes into contact with my skin?

• Rinse the affected area with plenty of water and seek medical attention if irritation persists.

Conclusion

TEMPO (2,2,6,6-Tetramethylpiperidine-1-oxyl) is a highly valuable organic chemistry reagent known for its stability and versatility in various oxidation reactions and other synthetic processes. Its ability to act as a catalyst and its role in different fields, including pharmaceuticals, material science, and biochemistry, make it an indispensable tool for chemists. By understanding its properties, uses, and handling precautions, you can effectively and safely incorporate TEMPO into your laboratory practices.