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2-bromophenol is an aromatic halogenated phenol compound commonly used as a building block in organic synthesis. It is an ortho-substituted bromophenol, where a bromine atom is attached to the benzene ring at the second position relative to the hydroxyl group (-OH). The presence of both hydroxyl and halogen groups makes it a versatile reagent in the synthesis of pharmaceuticals, agrochemicals, and fine chemicals.

Chemical Structure and PropertiesPropertyDescriptionChemical Name2-BromophenolMolecular FormulaC₆H₅BrOMolecular Weight173.01 g/molCAS Number95-56-7AppearanceWhite to pale yellow crystalline solidBoiling Point210°CMelting Point7°CDensity1.77 g/cm³SolubilitySlightly soluble in water, soluble in organic solvents like ethanol, ether, and chloroformChemical Structure

The structure of 2-bromophenol consists of a benzene ring with two functional groups:

1. Hydroxyl group (-OH) at the first position.
2. Bromine atom (Br) at the second position (ortho position).

This combination gives the molecule unique chemical and physical properties, including polarity, reactivity, and solubility.

Synthesis of 2-Bromophenol

2-Bromophenol can be synthesized by:

1. Bromination of Phenol:

   • Phenol undergoes electrophilic aromatic substitution with bromine in the presence of a catalyst (like FeBr₃), resulting in bromophenol. By controlling the reaction conditions, the ortho isomer (2-bromophenol) can be selectively produced.

   Reaction:

   C6H5OH+Br2→C6H4BrOH+HBr\text{C}_6\text{H}_5\text{OH} + \text{Br}_2 \rightarrow \text{C}_6\text{H}_4\text{BrOH} + \text{HBr}C6​H5​OH+Br2​→C6​H4​BrOH+HBr

2. Direct Bromination with NBS (N-Bromosuccinimide):

   • NBS is used as a brominating agent in the presence of a radical initiator (like light or peroxide) to selectively brominate phenol derivatives at the ortho position.

Applications of 2-Bromophenol

1. Intermediate in Pharmaceutical Synthesis:

   • 2-Bromophenol is a key starting material in the production of antifungal agents, analgesics, and anti-inflammatory drugs.
   • It is used to prepare brominated benzodiazepines and other heterocyclic compounds.

2. Building Block in Organic Synthesis:

   • It is used as a precursor for the synthesis of aryl ethers, aryl amines, and aryl halides.
   • The hydroxyl and bromine groups facilitate substitution and coupling reactions, such as:
     • Suzuki coupling
     • Buchwald-Hartwig amination
     • Ullmann reaction

3. Agrochemical Synthesis:

   • Used in the preparation of fungicides, herbicides, and pesticides.

4. Polymer Chemistry:

   • It is employed in the modification of polymers and resins, improving their chemical and thermal properties.

5. Dye and Pigment Manufacturing:

   • The compound is used in the synthesis of azo dyes and organic pigments.

6. Biochemical Studies:

   • It serves as a model compound in studying the interaction of phenolic compounds with biological systems, particularly their role in enzyme inhibition and antioxidant activity.

Reactivity of 2-Bromophenol

2-Bromophenol exhibits both nucleophilic and electrophilic reactivity due to the presence of the hydroxyl and bromine groups:

1. Nucleophilic Substitution (SNAr):

   • The bromine atom can be displaced by a nucleophile (e.g., amine, thiol, or alkoxide) to form various derivatives.

2. Electrophilic Substitution:

   • The hydroxyl group activates the benzene ring, making it more susceptible to further electrophilic substitutions, such as nitration, sulfonation, or alkylation.

3. Oxidation:

   • The hydroxyl group can be oxidized to form quinones or other oxidized phenol derivatives.

Safety and Handling

2-Bromophenol is classified as a hazardous substance and should be handled with care.

Hazards:

• Causes skin and eye irritation.
• Harmful if inhaled or ingested.
• Can cause environmental damage if released into water bodies.

Precautions:

• Wear PPE: Gloves, goggles, and a lab coat should be worn while handling.
• Work in a fume hood: Avoid inhaling vapors.
• Proper storage: Keep in a cool, dry place, away from heat, moisture, and incompatible substances (e.g., strong oxidizers).

First Aid Measures:

• Skin contact: Wash thoroughly with soap and water.
• Eye contact: Rinse with water for at least 15 minutes and seek medical attention.
• Inhalation: Move to fresh air immediately and seek medical help if symptoms persist.

Environmental Impact

2-Bromophenol can be toxic to aquatic life and should not be released into the environment. Proper waste disposal methods must be followed in compliance with local regulations.

Conclusion

2-Bromophenol is a valuable reagent in organic synthesis, particularly in the pharmaceutical and agrochemical industries. Its unique structure and reactivity make it an important intermediate in various chemical transformations. While it is a useful compound, appropriate safety precautions should be taken to handle it safely due to its hazardous properties.