Hydrolysis of Methyl Benzoate

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Hydrolysis of Methyl Benzoate
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Instructional Objectives - Highlights

• Reflux condenser
• Vacuum filtration

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Experimental Objectives

• Synthesize and isolate benzoic acid

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Experimental Procedure

• Reflux methyl benzoate in sodium hydroxide
  solution
• Neutralize with hydrochloric acid to precipitate
  benzoic acid.
• Collect precipitate by vacuum filtration

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Methyl Benzoate/Sodium Hydroxide Reflux

• Methyl benzoate
• Capped glass vials
• Sodium Hydroxide
• Dispenser cups

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Reflux Condenser

• Set-up
• Operation

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Reflux Condenser - Setup

• glass beads
• Burner close to flask bottom
• Wire mesh in close contact with flask
• Tight connection between condenser and flask
• Water in the bottom (hottest) and out the top
  (coolest).
• HAVE INSTRUCTOR INSPECT SETUP!!!!

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Reflux Condenser - Operation

• CONSTANT GENTLE BOIL
• Do not take walk or look away
• Gently jiggle if necessary
• Verify that vapors are not escaping

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Reflux Condenser - Cooling

• Turn off burner
• Drop ring and wire gauze
• Bring beaker of cold water up around flask
• KEEP water flowing in condenser

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Precipitation of Benzoic Acid

• 250 mL beaker
• Dropwise addition of HCl with stirring
• Litmus paper check for acidic solution
• Stirring rod
• Blue litmus paper turns red
• Place beaker in ice bath

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Isolation of Benzoic Acid

• Filter Flask/Buchner Funnel
• Attached to house vacuum
• Stabilized
• Dampened filter paper
• Transfer Reaction Solution
• Keep precipitate suspended
• Rinse with cold deionized water
• Filter and Dry
• Transfer to watch glass

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Clean-up

• Glass Vials
• Replace Cap
• Place in waste hood
• Glass beads
• Rinse in round bottom flask with low molarity
  NaOH
• Place in sieve in back sink
• Round bottom flask
• Wash inside and outside with DI water
• LEAVE on benchtop
• Condenser
• Do NOT clean
• LEAVE on benchtop with tubing

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Data Analysis Theoretical Yield

• Methyl Benzoate is limiting reactant

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Data Analysis Percent Yield