Organic synthesis and analysis

• What is the first step in the reaction involving alcoholic NH3 under heat and pressure?

  Step 1 is H2SO4.
• What is the purpose of using KOH aqueous in the reaction sequence?

  KOH aqueous is used for nucleophilic substitution.
• What type of reaction occurs with Br2 or Cl2 under UV light?

  Free radical substitution occurs.
• What is the result of heating KOH aqueous under reflux?

  It leads to nucleophilic substitution.
• What is the product of a reaction involving a primary amine and an alkane?

  The product is a halogenoalkane.
• What is the functional group of a carboxylic acid?

  –COOH
• What is the role of Na2Cr2O7/H+ in the oxidation of primary and secondary alcohols?

  It is used for oxidation reactions.
• What happens when a primary alcohol is oxidized with Na2Cr2O7/H+ and heat under reflux?

  It produces a carboxylic acid.
• What is the result of treating a secondary alcohol with Na2Cr2O7/H+ and heat?

  It undergoes oxidation to form a ketone.
• What is the product of the reaction between KCN in an ethanol/water mixture?

  A nitrile is formed.
• What is the purpose of using high pressure and a catalyst in the polymerization of alkenes?

  It facilitates the formation of poly(alkene).
• What is the result of nucleophilic addition-elimination with acyl chloride or acid anhydride?

  An ester is formed.
• What is the outcome of adding water at room temperature to a hydroxynitrile?

  It leads to nucleophilic addition-elimination.
• What is the result of treating a primary amine with an acyl chloride at room temperature?

  A secondary amide is formed.
• What is the purpose of using NaBH4 in organic reactions?

  It is used for reduction reactions.
• What is the result of esterification between alcohol and carboxylic acid with H2SO4?

  An ester is formed.
• How can esters and amides be hydrolyzed?

  By using NaOH and acids.
• What is the reagent used for electrophilic substitution of aromatic compounds?

  Conc nitric acid and conc sulfuric acid.
• What is the observation when an aldehyde reacts with Tollen's reagent?

  A silver mirror forms.
• What is the result of the reaction between sodium carbonate and a carboxylic acid?

  Effervescence of CO2 is observed.
• Why is it important not to seal the end of the condenser during reflux?

  To prevent the build-up of gas pressure which could cause an explosion.
• What is the purpose of using a Liebig condenser in reflux apparatus?

  To prevent organic vapours from escaping.

  
• What is the role of anti-bumping granules in distillation and reflux?

  To prevent vigorous, uneven boiling.
• What is the process of fractional distillation used for?

  To separate liquids with different boiling points.
• What is the purpose of using electric heaters for heating organic chemicals?

  To avoid the risk of fire from naked flames.
• How can the purity of a liquid be determined?

  By measuring its boiling point.
• What happens to the boiling point of a liquid under changing pressure?

  The boiling point changes with pressure variations.
• What is the significance of a sharp melting point in a pure substance?

  A sharp melting point indicates high purity.
• How does the presence of impurities affect the melting point of a substance?

  It lowers the melting point and broadens the melting range.
• What is the reagent used to test for alkenes?

  Bromine water.
• What is the observation when a primary alcohol is oxidized with sodium dichromate and sulfuric acid?

  The orange dichromate solution changes to green.
• What happens when acyl chloride reacts with silver nitrate?

  It produces vigorous reaction with steamy fumes of HCl and rapid white precipitate of AgCl.
• What is the result of warming a chloroalkane with silver nitrate?

  A slow formation of white precipitate of AgCl.
• What are the key steps in the recrystallization process for purifying an organic solid?

  1. Dissolve the impure compound in hot solvent.
  2. Hot filter to remove insoluble impurities.
  3. Cool the solution to form crystals.
  4. Use Buchner flask for suction filtration.
  5. Wash crystals with distilled water.
  6. Dry the crystals between absorbent paper.
• What are the observations for testing organic functional groups?

  • Alkene: Orange bromine water decolorizes.
  • Aldehyde: Blue Fehling’s solution turns red.
  • Carboxylic acid: Effervescence with sodium carbonate.
  • Chloroalkane: White precipitate with silver nitrate.
• What are the steps involved in purifying an organic liquid using a separating funnel?

  1. Add distillate to a separating funnel.
  2. Wash with sodium hydrogencarbonate or saturated sodium chloride solution.
  3. Allow layers to separate and discard the aqueous layer.
  4. Add drying agent to the organic layer.
  5. Decant and distill to collect pure product.
• What are the conditions and observations for the oxidation of aldehydes using Tollen's reagent?

  • Conditions: Heat gently.
  • Observation: Silver mirror forms on the test tube.
• What are the conditions and observations for the oxidation of aldehydes using Fehling's solution?

  • Conditions: Heat gently.
  • Observation: Blue Cu²⁺ ions change to red precipitate of Cu₂O.
• What are the key features of a Liebig condenser in reflux apparatus?

  • Prevents organic vapours from escaping.
  • Must not be sealed at the top.
  • Has two openings for water in and out.
• What are the key points to remember when measuring boiling points for purity assessment?

  • Thermometer should be above the boiling liquid.
  • Pressure affects boiling point.
  • Boiling point alone may not accurately identify substances.