Phenols - Riemer-Tiemann reaction
- Introduction to phenols
- Definition: Organic compounds that contain a hydroxyl group (-OH) attached to an aromatic ring
- Examples:
- Phenol (C6H6O) - simplest aromatic alcohol
- 2,4-dinitrophenol (C6H4N2O5) - used as a pesticide
- Riemer-Tiemann reaction
- Definition: A method used to convert phenols into ortho-substituted phenols
- Reactants:
- Phenol
- Chloroform (CHCl3)
- Sodium hydroxide (NaOH)
- Equation: Phenol + CHCl3 + NaOH → Ortho-substituted phenol + NaCl + H2O
- Mechanism of the Riemer-Tiemann reaction
- Step 1: Deprotonation of phenol by NaOH
- Step 2: Formation of dichlorocarbene (CHCl3 + NaOH → CHCl2Na + NaCl + H2O)
- Step 3: Attack of dichlorocarbene on the ortho position of the deprotonated phenol
- Step 4: Acidification to obtain the ortho-substituted phenol
- Example:
- Reaction: Phenol + CHCl3 + NaOH → 2-Hydroxy-5-chlorobenzaldehyde + NaCl + H2O
- Importance of the Riemer-Tiemann reaction
- Synthetic applications:
- Synthesis of ortho-substituted phenols for pharmaceutical purposes
- Preparation of intermediates for various organic reactions
- Discovery of new compounds with potential biological activities
- Limitations of the Riemer-Tiemann reaction
- Only works with electron-rich phenols
- Reactivity decreases with increasing steric hindrance on the phenolic ring
- Chloroform is toxic and environmentally hazardous
Aromatic Amines - Sandmeyer reaction
- Introduction to aromatic amines
- Definition: Organic compounds that contain a nitrogen atom attached to an aromatic ring
- Examples:
- Aniline (C6H5NH2) - simplest aromatic amine
- N,N-dimethylaniline (C8H11N) - used as a dye intermediate
- Sandmeyer reaction
- Definition: A method used to convert aromatic amines into different functional groups
- Reactants:
- Aromatic amine
- Sodium nitrite (NaNO2)
- Mineral acid (e.g., HCl, H2SO4)
- Cu(I) salt (e.g., CuCl, CuBr)
- Products: Can include aryl halides, aryl nitriles, and aryl thiols
- Example:
- Reaction: Aniline + NaNO2 + HCl → Chlorobenzene + NaCl + N2 + H2O
- Mechanism of the Sandmeyer reaction
- Step 1: Formation of diazonium salt
- Step 2: Decomposition of diazonium salt to generate the desired product
- Example:
- Reaction: Aniline + NaNO2 + HCl → Chlorobenzene + NaCl + N2 + H2O
- Importance of the Sandmeyer reaction
- Versatile method for the synthesis of various functional groups
- Widely used in the pharmaceutical and dye industries
- Limitations of the Sandmeyer reaction
- Limited to primary aromatic amines
- Requires careful control of reaction conditions due to the reactivity of diazonium salts
- Side reactions and by-products can occur in complex reaction systems
Phenols - Riemer-Tiemann reaction
- Introduction to phenols
- Definition: Organic compounds that contain a hydroxyl group (-OH) attached to an aromatic ring
- Examples:
- Phenol (C6H6O) - simplest aromatic alcohol
- 2,4-dinitrophenol (C6H4N2O5) - used as a pesticide
- Riemer-Tiemann reaction
- Definition: A method used to convert phenols into ortho-substituted phenols
- Reactants:
- Phenol
- Chloroform (CHCl3)
- Sodium hydroxide (NaOH)
- Equation: Phenol + CHCl3 + NaOH → Ortho-substituted phenol + NaCl + H2O
- Mechanism of the Riemer-Tiemann reaction
- Step 1: Deprotonation of phenol by NaOH
- Step 2: Formation of dichlorocarbene (CHCl3 + NaOH → CHCl2Na + NaCl + H2O)
- Step 3: Attack of dichlorocarbene on the ortho position of the deprotonated phenol
- Step 4: Acidification to obtain the ortho-substituted phenol
- Example:
- Reaction: Phenol + CHCl3 + NaOH → 2-Hydroxy-5-chlorobenzaldehyde + NaCl + H2O
- Importance of the Riemer-Tiemann reaction
- Synthetic applications:
- Synthesis of ortho-substituted phenols for pharmaceutical purposes
- Preparation of intermediates for various organic reactions
- Discovery of new compounds with potential biological activities
- Limitations of the Riemer-Tiemann reaction
- Only works with electron-rich phenols
- Reactivity decreases with increasing steric hindrance on the phenolic ring
- Chloroform is toxic and environmentally hazardous
Aromatic Amines - Sandmeyer reaction
- Introduction to aromatic amines
- Definition: Organic compounds that contain a nitrogen atom attached to an aromatic ring
- Examples:
- Aniline (C6H5NH2) - simplest aromatic amine
- N,N-dimethylaniline (C8H11N) - used as a dye intermediate
- Sandmeyer reaction
- Definition: A method used to convert aromatic amines into different functional groups
- Reactants:
- Aromatic amine
- Sodium nitrite (NaNO2)
- Mineral acid (e.g., HCl, H2SO4)
- Cu(I) salt (e.g., CuCl, CuBr)
- Products: Can include aryl halides, aryl nitriles, and aryl thiols
- Example:
- Reaction: Aniline + NaNO2 + HCl → Chlorobenzene + NaCl + N2 + H2O
- Mechanism of the Sandmeyer reaction
- Step 1: Formation of diazonium salt
- Step 2: Decomposition of diazonium salt to generate the desired product
- Example:
- Reaction: Aniline + NaNO2 + HCl → Chlorobenzene + NaCl + N2 + H2O
- Importance of the Sandmeyer reaction
- Versatile method for the synthesis of various functional groups
- Widely used in the pharmaceutical and dye industries
- Limitations of the Sandmeyer reaction
- Limited to primary aromatic amines
- Requires careful control of reaction conditions due to the reactivity of diazonium salts
- Side reactions and by-products can occur in complex reaction systems
Slide 21
Phenols - Riemer-Tiemann reaction
- Introduction to phenols
- Definition: Organic compounds that contain a hydroxyl group (-OH) attached to an aromatic ring
- Examples:
- Phenol (C6H6O) - simplest aromatic alcohol
- 2,4-dinitrophenol (C6H4N2O5) - used as a pesticide
Slide 22
Riemer-Tiemann reaction
- Definition: A method used to convert phenols into ortho-substituted phenols
- Reactants:
- Phenol
- Chloroform (CHCl3)
- Sodium hydroxide (NaOH)
- Equation: Phenol + CHCl3 + NaOH → Ortho-substituted phenol + NaCl + H2O
Slide 23
Mechanism of the Riemer-Tiemann reaction
- Step 1: Deprotonation of phenol by NaOH
- Step 2: Formation of dichlorocarbene (CHCl3 + NaOH → CHCl2Na + NaCl + H2O)
- Step 3: Attack of dichlorocarbene on the ortho position of the deprotonated phenol
- Step 4: Acidification to obtain the ortho-substituted phenol
Slide 24
Mechanism of the Riemer-Tiemann reaction (continued)
- Example:
- Reaction: Phenol + CHCl3 + NaOH → 2-Hydroxy-5-chlorobenzaldehyde + NaCl + H2O
Slide 25
Importance of the Riemer-Tiemann reaction
- Synthetic applications:
- Synthesis of ortho-substituted phenols for pharmaceutical purposes
- Preparation of intermediates for various organic reactions
- Discovery of new compounds with potential biological activities
Slide 26
Limitations of the Riemer-Tiemann reaction
- Only works with electron-rich phenols
- Reactivity decreases with increasing steric hindrance on the phenolic ring
- Chloroform is toxic and environmentally hazardous
Slide 27
Aromatic Amines - Sandmeyer reaction
- Introduction to aromatic amines
- Definition: Organic compounds that contain a nitrogen atom attached to an aromatic ring
- Examples:
- Aniline (C6H5NH2) - simplest aromatic amine
- N,N-dimethylaniline (C8H11N) - used as a dye intermediate
Slide 28
Sandmeyer reaction
- Definition: A method used to convert aromatic amines into different functional groups
- Reactants:
- Aromatic amine
- Sodium nitrite (NaNO2)
- Mineral acid (e.g., HCl, H2SO4)
- Cu(I) salt (e.g., CuCl, CuBr)
Slide 29
Sandmeyer reaction (continued)
- Products: Can include aryl halides, aryl nitriles, and aryl thiols
- Example:
- Reaction: Aniline + NaNO2 + HCl → Chlorobenzene + NaCl + N2 + H2O
Slide 30
Importance and limitations of the Sandmeyer reaction
- Importance:
- Versatile method for the synthesis of various functional groups
- Widely used in the pharmaceutical and dye industries
- Limitations:
- Limited to primary aromatic amines
- Requires careful control of reaction conditions due to the reactivity of diazonium salts
- Side reactions and by-products can occur in complex reaction systems