Aromatic Alcohols and Their Properties

Aromatic Alcohol

• Benzyl Alcohol is an example of an aromatic alcohol.

Functional Groups

• The functional group of alcohols is -OH (hydroxyl group).
• Methanol (CH3OH) is an example of an alcohol.
• Ethanol (C2H5OH) is also an example of an alcohol.
• Glycerol is a triol and has three -OH groups

Physical Properties of Alcohols

• Methanol, Ethanol, and Glycerol are all liquids at room temperature.
• Methanol is colorless, with a faint alcoholic odor.
• Ethanol is colorless, with a slightly stronger alcoholic odor.
• Glycerol is a viscous liquid and is odorless.
• Methanol and ethanol are miscible with water.

Chemical Properties of Alcohols

• Action of Dry Heat:

  • All three alcohols are flammable, but Glycerol burns with a smoky flame.
  • All three alcohols evaporate when heated.
  • There is no change in color or odor when they are heated.
  • No residue is observed after heating.

• Action of NaOH:

  • No reaction occurs with cold or hot NaOH.

• Action of Soda Lime:

  • The text does not mention any reaction with soda lime.

• Action of FeCl3:

  • No reaction occurs with FeCl3.

• Action of Concentrated H2SO4:

  • Methanol and ethanol do not react with concentrated H2SO4.
  • Glycerol reacts with concentrated H2SO4 to produce toxic fumes and charring.

Reactions of Alcohols

• Sodium Metal Test:

  • All three alcohols react with Sodium metal, evolving Hydrogen gas.
  • The reaction is represented by the general equation: 2R-OH + 2Na → 2R-O-Na + H2
  • The reaction is a displacement reaction where the hydrogen in the -OH group gets replaced by sodium.

• Esterification:

  • Methanol: Reacts with Salicylic acid to produce Methylsalicylate (Vicks odor)
  • Ethanol: Reacts with Acetic acid to produce Ethyl acetate (Fruity odor)
  • Glycerol reacts with acids to form fixed esters.

• Partial Oxidation:

  • Methanol: Oxidized to Formaldehyde using a copper wire. Formaldehyde reacts with Schiff's reagent to give a Magenta red color.
  • Ethanol: Oxidized to Acetaldehyde using a copper wire. Acetaldehyde also reacts with Schiff's reagent to give a Magenta red color.
  • Glycerol does not react with Schiff's reagent.

• Complete Oxidation:

  • Methanol: Oxidized to Formic acid.
  • Ethanol: Oxidized to Acetic acid.
  • Glycerol does not undergo complete oxidation.

Specific Reactions and Tests

• Preparation of Methylsalicylate:

  • To prepare Methylsalicylate, mix 2 grams of Salicylic acid, 2 ml of Methanol, and 1 ml of Conc. H2SO4.
  • Shake the mixture and heat for 1 minute.
  • Pour the contents into a beaker containing 20 ml of Na2CO3 solution.
  • The solution will have a Vicks odor.

• Preparation of Ethyl acetate:

  • To prepare Ethyl acetate, mix 1 ml of Acetic acid, 2 ml of Ethanol, and 1 ml of concentrated H2SO4.
  • Shake the mixture, heat for 1 minute, and then pour into a beaker containing 20 ml of Na2CO3 solution.
  • The solution will have a fruity odor.