Experiment 6: EXTRACTION of ANALGESICS

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.

Before coming to lab…  Watch the following videos to help you understand the techniques that will be used. Extraction chemistry-lab /view/ Vacuum Filtration #docid= Drying Organic Solvents chemistry-lab /view/

ACTIVE INGREDIENTS— GOODY’S POWDERS 500 mg/powder 325 mg/powder

ACID–BASE EXTRACTION— CHEMICAL EQUATIONS

ACID–BASE EXTRACTION FLOW CHART

USING A SEPARATORY FUNNEL Be sure the stopcock is in the horizontal position (closed) before adding any liquid! Be sure the stopper is tightly sealed before inverting! Always keep one finger on the stopper!

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…

DRYING ORGANIC SOLVENTS Add a small amount of MgSO 4 to the organic solution and swirl. If the MgSO 4 continues to clump and sink to the bottom, continue to add. If the MgSO 4 settles out of solution slowly (like a snow globe), the solution is dry.

OVERVIEW  Perform acid/base extraction using separatory funnel.  Isolate ASPIRIN and ACETAMINOPHEN in separate flasks. AO ACETAMINOPHEN (O) ASPIRIN SALT (A)

OVERVIEW ACETAMINOPHEN… Dry organic layer with MgSO 4. Suction filter to remove MgSO 4 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.

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.

THEORETICAL RECOVERY  For this experiment, we dissolved 2 Goody’s powders in 25 mL of ethyl acetate.  In each Goody’s powder, there is g of aspirin and g of acetaminophen.  Theoretical Recovery: g per powder X 2 powders = ? g of Aspirin g per powder X 2 powders = ? g of Acetaminophen

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)

Table 6.1: Experimental Results AspirinAcetaminophen Theoretical recovery after extraction (g)calculated Actual recovery after extraction (g) Obtain weight next lab! Obtain weight this lab! % Recovery after extractioncalculated

Table 6.2: HPLC Results Compound HPLC retention times (min) and area % StandardsAspirin Sample Acetaminophen Sample R t (min) R t (min) area %R t (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!

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!

WASTE MANAGEMENT  The drying agent (MgSO 4 ) 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”.

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.

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.