Experiment 6:

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Experiment 6

• EXTRACTION of ANALGESICS

2
Objectives

• To learn the techniques of acid-base extraction,
  drying organic solvents, and vacuum filtration.
• To separate aspirin from acetaminophen using the
  extraction technique.
• To determine the efficiency of separation and the
  purity of compounds using HPLC analysis.

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Before coming to lab

• Watch the following videos to help you understand
  the techniques that will be used.
• Extraction
• http//www.wonderhowto.com/how-to/video/how-to-do-
  a-liquid-liquid-extraction-in-the-chemistry-lab-25
  9811/view/
• Vacuum Filtration
• http//video.google.com/videoplay?docid-454145319
  4468704643docid1104445520143750871
• Drying Organic Solvents
• http//www.wonderhowto.com/how-to/video/how-to-dry
  -an-organic-solution-in-the-chemistry-lab-259802/v
  iew/

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ACTIVE INGREDIENTS GOODYS POWDERS
500 mg/powder 325 mg/powder
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ACIDBASE EXTRACTIONCHEMICAL EQUATIONS
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ACIDBASE EXTRACTION FLOW CHART
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USING A SEPARATORY FUNNEL

• Be sure the stopper is tightly sealed before
  inverting!
• Always keep one finger on the stopper!

• Be sure the stopcock is in the horizontal
  position (closed) before adding any liquid!

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VACUUM FILTRATION TECHNIQUE

• Always clamp the suction flask to a ring stand!
• Run the red vacuum hose to the yellow vacuum
  line to pull suction!

To vacuum line
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DRYING ORGANIC SOLVENTS

• Add a small amount of MgSO4 to the organic
  solution and swirl.

• If the MgSO4 continues to clump and sink to the
  bottom, continue to add.
• If the MgSO4 settles out of solution slowly
  (like a snow globe), the solution is dry.

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OVERVIEW

• Perform acid/base extraction using separatory
  funnel.
• Isolate ASPIRIN and ACETAMINOPHEN in separate
  flasks.

ACETAMINOPHEN (O)
ASPIRIN SALT (A)
A
O
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OVERVIEW

• ACETAMINOPHEN
• Dry organic layer with MgSO4.
• Suction filter to remove MgSO4 from liquid.
• Evaporate liquid on hotplate.
• Reweigh to obtain final weight calculate
  recovery.
• Dissolve solid in REAGENT acetone.
• Submit HPLC sample.
• Transfer to large sample vial and submit to
  instructor until next lab period.

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OVERVIEW

• ASPIRIN
• Add acid to recover solid aspirin.
• Suction filter to recover solid aspirin.
• Submit HPLC sample.
• Secure aspirin in large filter paper and submit
  to instructor until next lab period.
• NEXT LAB PERIOD
• Obtain final weight of aspirin.
• Calculate recovery.
• Prepare sample for melting point analysis.

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THEORETICAL RECOVERY

• For this experiment, we dissolved 2 Goodys
  powders in 25 mL of ethyl acetate.
• In each Goodys powder, there is 0.500 g of
  aspirin and 0.325 g of acetaminophen.
• Theoretical Recovery
• 0.500 g per powder X 2 powders ? g of Aspirin
• 0.325 g per powder X 2 powders ? g of
  Acetaminophen

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PERCENT RECOVERY

• After the product has been dried sufficiently,
  the ACTUAL YIELD can be determined.
• In theory, you should be able to recover 100 of
  each compound, however this is not always the
  case.
• In order to determine the success of your
  recovery, the percent yield is calculated as
  follows
• Percent recovery actual recovery (g)
  X 100
• theoretical recovery (g)

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Table 6.1 Experimental Results
Aspirin Acetaminophen
Theoretical recovery after extraction (g) calculated calculated
Actual recovery after extraction (g) Obtain weight next lab! Obtain weight this lab!
Recovery after extraction calculated calculated
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Table 6.2 HPLC Results
Compound HPLC retention times (min) and area HPLC retention times (min) and area HPLC retention times (min) and area HPLC retention times (min) and area HPLC retention times (min) and area
Compound Standards Aspirin Sample Aspirin Sample Acetaminophen Sample Acetaminophen Sample
Compound Rt (min) Rt (min) area Rt (min) area
Aspirin
Acetaminophen

• Samples containing a single compound are
  considered PURE samples, while those containing
  both compounds are considered MIXED (IMPURE)
  samples.
• Be sure to attach both sample chromatograms to
  final lab report!

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SAFETY CONCERNS

• Acetone and ethyl acetate are extremely
  flammable! Wear safety goggles at all times and
  use extreme caution when heating!
• Hydrochloric acid is corrosive!

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WASTE MANAGEMENT

• The drying agent (MgSO4) and filter paper should
  be placed in the container labeled SOLID WASTE
  provided in the hood.
• Place all liquid waste in the container labeled
  LIQUID WASTE.

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IN LAB QUESTIONS (The following questions
should be answered in laboratory notebook.)

• Draw a complete mechanism for the reaction which
  occurs between aspirin and 10 NaHCO3 using
  actual chemical structures and mechanism arrows
  to indicate electron flow.

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IN LAB QUESTIONS (The following questions
should be answered in laboratory notebook.)

• Draw a complete mechanism for the reaction which
  occurs between acetaminophen and 10 NaOH using
  actual chemical structures and mechanism arrows
  to indicate electron flow.