Preparation of Acetanilide Experiment
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Questions and Answers

What is the aim of experiment 10.1?

  • To prepare aniline
  • To prepare glacial acetic acid
  • To prepare acetanilide (correct)
  • To prepare acetic acid

    • Which reagent is used for acetylation if acetic anhydride is not available?

  • Pyridine
  • Acetyl chloride (correct)
  • Pumice stone
  • Acetic acid

    • What is the function of the air condenser in this experiment?

  • To filter the reaction mixture
  • To provide heat for the reaction
  • To cool the reaction mixture (correct)
  • To measure the volume of the reaction mixture

    • What is the purpose of adding pumice stones in the round bottom flask?

    <p>To prevent superheating and bumping</p> Signup and view all the answers

    What is the role of the sand bath in this experiment?

    <p>To provide heat for the reaction</p> Signup and view all the answers

    What is the material required for acetylation if acetic anhydride is not available?

    <p>Dry pyridine</p> Signup and view all the answers

    What is the purpose of washing the solid with cold water in the acetanilide preparation process?

    <p>To remove impurities and neutralize the filtrate</p> Signup and view all the answers

    Why is it important to handle acetic anhydride and acetyl chloride carefully in the acetanilide preparation process?

    <p>They cause irritation to the eyes and strong fumes in air</p> Signup and view all the answers

    If aniline sample is too much coloured, what precaution should be taken before carrying out the experiment?

    <p>Distill it before carrying out the experiment</p> Signup and view all the answers

    What should be done if the boiling tube becomes unbearable to touch during the acetanilide preparation process?

    <p>Cool it under tap water</p> Signup and view all the answers

    What is the role of pyridine in the acetanilide preparation process?

    <p>Catalyze the reaction between aniline and acetic acid</p> Signup and view all the answers

    What is the purpose of recrystallizing the crude acetanilide with hot water?

    <p>To obtain white shining needle-shaped crystals</p> Signup and view all the answers

    Why should one determine the melting point of perfectly dried and recrystallized sample of acetanilide?

    <p>To confirm the purity of the compound</p> Signup and view all the answers

    What is an alternative method for preparing acetanilide if acetic anhydride or pyridine is not available?

    <p>$Aniline + Acetic\thinspace acid$</p> Signup and view all the answers

    Why is it important to use perfectly dry apparatus in the alternative method for preparing acetanilide?

    <p>$To\thinspace prevent\thinspace contamination$</p> Signup and view all the answers

    What is the function of the air condenser in the preparation of acetanilide?

    <p>To ensure efficient reflux of the reaction mixture</p> Signup and view all the answers

    What precaution should be taken if the aniline sample is highly colored before carrying out the experiment?

    <p>Replace aniline with a fresh, colorless sample</p> Signup and view all the answers

    Why is it important to determine the melting point of perfectly dried and recrystallized sample of acetanilide?

    <p>To verify the purity of the acetanilide product</p> Signup and view all the answers

    What is the role of pyridine in the acetanilide preparation process?

    <p>Catalyzing the reaction between aniline and acetic anhydride</p> Signup and view all the answers

    Why should one handle acetic anhydride and acetyl chloride carefully in the acetanilide preparation process?

    <p>Due to their high reactivity with water and air</p> Signup and view all the answers

    What is the material required for acetylation if acetic anhydride is not available?

    <p>Acetyl chloride and dry pyridine</p> Signup and view all the answers

    What is the purpose of adding a few drops of methanol or ethanol when recrystallising the acetanilide?

    <p>To reduce impurities in the recrystallised acetanilide</p> Signup and view all the answers

    Why should acetyl chloride be added in lots (0.3 mL at a time) in the preparation of acetanilide?

    <p>To prevent excessive foaming</p> Signup and view all the answers

    What precaution should be taken if the aniline sample is too much colored?

    <p>Distill it before carrying out the experiment</p> Signup and view all the answers

    Why is it important to determine the melting point of perfectly dried and recrystallized sample of acetanilide?

    <p>To verify its purity</p> Signup and view all the answers

    What is an alternative method for preparing acetanilide if acetic anhydride or pyridine is not available?

    <p>Using glacial acetic acid and aniline only</p> Signup and view all the answers

    Why should one handle pyridine with extreme caution in the acetanilide preparation process?

    <p>It is toxic and can cause serious harm if inhaled or absorbed through skin</p> Signup and view all the answers

    What is the purpose of washing the solid 2-3 times with cold water in the acetanilide preparation process?

    <p>To remove soluble impurities</p> Signup and view all the answers

    What is the function of recrystallizing the crude acetanilide with hot water?

    <p>To enhance the melting point of acetanilide</p> Signup and view all the answers

    What is the material required for acetylation if acetic anhydride is not available?

    <p>Aniline and glacial acetic acid only</p> Signup and view all the answers

    Why should acetylchloride be added in lots (0.3 mL at a time) in the preparation of acetanilide?

    <p>To prevent excessive foaming</p> Signup and view all the answers

    Study Notes

    Experiment 10.1 Aim

    • Aim is to prepare acetanilide through the acetylation of aniline.

    Alternative Reagents for Acetylation

    • If acetic anhydride is unavailable, acetyl chloride or mixed anhydrides can be used for acetylation.

    Air Condenser Function

    • The air condenser is used to prevent loss of volatile substances and maintain temperature during the reaction.

    Pumice Stones Purpose

    • Pumice stones are added to the round bottom flask to promote even boiling and prevent bumping of liquids.

    Role of Sand Bath

    • The sand bath provides uniform heating, allowing for controlled temperatures in the reaction process.

    Washing with Cold Water

    • Washing solid with cold water removes unreacted starting materials and impurities from the acetanilide.

    Handling Acetic Anhydride and Acetyl Chloride

    • These reagents are corrosive and can cause skin burns; careful handling reduces risk of accidents.

    Precaution for Colored Aniline

    • If the aniline is highly colored, it may need to be purified before use to avoid contamination in the product.

    Addressing High Temperature of Boiling Tube

    • If the boiling tube becomes hot to touch, it should be removed from the heat source to prevent risks of burns.

    Pyridine's Role

    • Pyridine acts as a base and solvent, facilitating the acetylation process during acetanilide preparation.

    Recrystallization Purpose

    • Recrystallizing crude acetanilide in hot water purifies the product by allowing impurities to be separated.

    Melting Point Determination

    • Determining the melting point of recrystallized acetanilide assesses purity and confirms the identity of the compound.

    Alternative Preparation Method

    • Acetanilide can also be prepared using anhydrous sodium acetate or by using alternative acetylation methods if key reagents are unavailable.

    Importance of Dry Apparatus

    • Using perfectly dry apparatus is crucial in preventing hydrolysis of acetyl chlorides or other sensitive reagents.

    Adding Methanol or Ethanol

    • A few drops of methanol or ethanol added during recrystallization help improve solubility and clarity of the acetanilide crystals.

    Incremental Addition of Acetyl Chloride

    • Acetyl chloride should be added slowly (0.3 mL at a time) to control the reaction and prevent excessive heat build-up that leads to side reactions.

    Repetitive Washing of Solid

    • Repeated washing (2-3 times) with cold water ensures thorough removal of residual reactants and undesired by-products.

    Caution with Pyridine

    • Extreme caution is necessary while handling pyridine due to its toxicity and irritating properties upon contact.

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    Description

    Learn about the preparation of acetanilide through the acetylation reaction in the laboratory setting. Understand the process of replacing a hydrogen atom of the aniline compound to obtain acetanilide.

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