Phenols

  • Introduction
    • Definition of phenols
    • Properties of phenols
    • Structure of phenols
    • Classification of phenols
  • Electrophilic substitution reactions
    • Electrophilic substitution reactions due to the aryl nucleus
    • Reactions with halogens
    • Reactions with nitric acid
    • Reactions with sulfuric acid
    • Reactions with concentrated nitric acid and sulfuric acid mixture
  • Examples of electrophilic substitution reactions
    • Bromination of phenol
    • Nitration of phenol
    • Sulfonation of phenol
    • Formation of a picric acid
  • Mechanism of electrophilic substitution reactions
    • Introduction to the mechanism
    • Step-by-step explanation
    • Role of the aryl group in the mechanism
  • Effect of substituents on the reactivity of phenols
    • Explanation of the effect
    • Electron-donating groups
    • Electron-withdrawing groups
    • Ortho-para directing and meta directing groups
  • Evidence for the mechanism
    • Experimental observations
    • Spectroscopic evidence
    • Confirmation of the mechanism through isotopic labeling experiments
  • Comparison with benzene
    • Differences between the reactivity of phenols and benzene
    • Unique properties of phenols
  • Industrial applications
    • Use of phenols in the production of plastics and resins
    • Use of phenols in the synthesis of pharmaceuticals
  • Summary and conclusion
    • Recap of key points discussed
    • Importance of understanding the reactions of phenols

Slide 11

Phenols

  • Reactions of Phenols (Due to aryl Nucleus)
  • Electrophilic substitution reactions

Slide 12

Electrophilic substitution reactions:

  • Reactions with halogens
  • Reactions with nitric acid
  • Reactions with sulfuric acid
  • Reactions with concentrated nitric acid and sulfuric acid mixture

Slide 13

Examples of electrophilic substitution reactions:

  • Bromination of phenol
    • Equation: C6H5OH + Br2 -> C6H5Br + HBr
    • Explanation: Phenol reacts with bromine to form bromophenol and hydrogen bromide gas.

Slide 14

Examples of electrophilic substitution reactions (cont.):

  • Nitration of phenol
    • Equation: C6H5OH + HNO3 -> C6H4(NO2)OH + H2O
    • Explanation: Phenol reacts with nitric acid to form nitrophenol and water.

Slide 15

Examples of electrophilic substitution reactions (cont.):

  • Sulfonation of phenol
    • Equation: C6H5OH + SO3 -> C6H4(SO3H)OH
    • Explanation: Phenol reacts with sulfur trioxide to form sulfonated phenol.

Slide 16

Examples of electrophilic substitution reactions (cont.):

  • Formation of a picric acid
    • Equation: C6H5OH + HNO3 -> C6H2(NO2)3OH + H2O
    • Explanation: Phenol reacts with nitric acid to form picric acid and water.

Slide 17

Mechanism of electrophilic substitution reactions:

  • Introduction to the mechanism
  • Step-by-step explanation
  • Role of the aryl group in the mechanism

Slide 18

Effect of substituents on the reactivity of phenols:

  • Explanation of the effect
  • Electron-donating groups
  • Electron-withdrawing groups
  • Ortho-para directing and meta directing groups

Slide 19

Evidence for the mechanism:

  • Experimental observations
  • Spectroscopic evidence
  • Confirmation of the mechanism through isotopic labeling experiments

Slide 20

Comparison with benzene:

  • Differences between the reactivity of phenols and benzene
  • Unique properties of phenols

Slide 21

Evidence for the mechanism (cont.):

  • Experimental observations
    • Formation of colored products
    • Formation of by-products
  • Spectroscopic evidence
    • IR spectroscopy
    • NMR spectroscopy
    • UV-Vis spectroscopy
  • Confirmation of the mechanism through isotopic labeling experiments
    • Incorporation of labeled atoms into the product
    • Analysis of isotopic distribution in the product

Slide 22

Comparison with benzene (cont.):

  • Differences between the reactivity of phenols and benzene
    • Phenol is more reactive than benzene due to the presence of the hydroxyl group
    • Electrophilic substitution reactions in phenols occur at the ortho and para positions
    • Benzene undergoes electrophilic substitution reactions predominantly at the meta position
  • Unique properties of phenols
    • Phenols have higher boiling points compared to hydrocarbons of similar molecular weight
    • Phenols are acidic in nature due to the presence of the hydroxyl group
    • Phenols can form hydrogen bonds with other molecules, leading to higher intermolecular forces

Slide 23

Industrial applications of phenols:

  • Use of phenols in the production of plastics and resins
    • Phenol-formaldehyde resin (Bakelite) - used in electrical insulators and molding compounds
    • Phenol-acrylic resin (Coating resin) - used as a protective coating for metal surfaces
  • Use of phenols in the synthesis of pharmaceuticals
    • Phenol derivatives are used as intermediates in the synthesis of various drugs
    • Salicylic acid, derived from phenol, is the precursor for aspirin

Slide 24

Summary and conclusion:

  • Recap of key points discussed
    • Phenols are compounds with a hydroxyl group attached to an aromatic ring
    • Phenols undergo electrophilic substitution reactions due to the aryl nucleus
    • The reactivity of phenols can be influenced by substituents and their positions
    • Evidence such as experimental observations and spectroscopic analysis support the proposed mechanism
    • Phenols have unique properties and find applications in various industries
  • Importance of understanding the reactions of phenols
    • Phenols play a significant role in organic synthesis and have important applications in diverse fields

Slide 25

References:

  1. Morrison, R. T., & Boyd, R. N. (1999). Organic Chemistry. Prentice Hall.
  1. Carey, F. A., & Atkins, R. C. (2012). Organic Chemistry. McGraw-Hill.
  1. March, J. (2001). Advanced Organic Chemistry, Reactions, Mechanisms, and Structure. Wiley.
  1. Vollhardt, K. P. C., & Schore, N. E. (2014). Organic Chemistry: Structure and Function. W.H. Freeman and Company.