054_w2-1 - 1/28/10 Week 2 CHEM 054 How do we synthesize new...

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Unformatted text preview: 1/28/10 Week 2 CHEM 054 How do we synthesize new substances? LET'S REVIEW You need to wear: Long pants Apron Goggles Close-toed shoes CHEM 054 You need to bring: Lab Notebook Laptop or calculator Lab Handouts Lab Notebooks What are the guidelines? CHEM 054 Make recordings in INK. Initial bottom of each page. Add title, partners, date, etc to top of Hirst page. Put your name on each page. Complete and accurate record of your work. Neat and organized (with UNITS). Turn the COPIES in with your report. 1 1/28/10 Pre-lab & Report Format CHEM 054 Beginning questions Safety Procedure Data Claims Evidence ReHlections Post-Lab Questions Note: Final BQs and procedure should be included in the report. Where are we going? UNIT 1: Investigating Reactions UNIT 2: Controlling Reactions CHEM 054 UNIT 3: Applications of Reactions We will now start to explore the ideas and techniques used to "synthesize" new substances. Chemical Synthesis Chemical synthesis has given us, among other things, many of the medicinal drugs that have dramatically increased life quality and span in the past 100 years. CHEM 054 Aspirin - 1880s Heroin 1890's Sulfa drugs 1940's Statins 1980's 2 1/28/10 Your Challenge CHEM 054 Imagine that you work for a drug company interested in testing a new procedure to synthesize aspirin. You have been asked to evaluate whether the procedure is feasible, and explore ways to increase the yield. What do you have to do to complete your task? Initial Ideas CHEM 054 Discuss in your groups what types of tests you have to do and what type of information you need in order to evaluate this reaction and maximize the yield. C7H6O3 + C4H6O3 C9H8O4 + C2H4O2 Salicylic acid Acetic anhydride Acetyl salicylic acid (Aspirin) Acetic acid Safety CHEM 054 The best source of information regarding the dangers of chemicals The Material Safety Data Sheet. 3 1/28/10 Lets think! CHEM 054 Create a microscopic representation of this reaction with five salicylic acids and eight acetic anhydrides. Acid catalyst Salicylic acid Acetic Anhydride H H H H H H What is the `limiting reagent"? Reaction Analysis Acid Catalyst CHEM 054 It is proposed to use 3.0 g of C7H6O3 with 6 mL of C4H6O3 ( = 1.082 g/mL ) to do the reaction. Are the reactants in stoichiometric proportions? If not, which one is the limiting reactant? From the economic point of view, is this a "smart" choice of amounts? Why? Theoretical Yield Acid Catalyst CHEM 054 Calculate the maximum amount of Aspirin you will be able to synthesize. This amount is called the "Theoretical Yield." Why should you expect a lower yield than this? 4 1/28/10 Actual or Percent Yield How are you going to calculate the actual yield of your reaction? What measurements and calculation do you need to make? CHEM 054 Brief Outline CHEM 054 Following the procedure (in catalyst from 53 and on Bb), manufacture some aspirin . It is proposed to use 3.0 g of C7H6O3 with 6 mL of C4H6O3 ( = 1.082 g/mL ) to do the reaction. Recrystallize your aspiring product. (Solvents = Water or ethanol?) Claims and Evidence CHEM 054 Based on the results of your experiments, record your major claims (percent yield) and the evidence that you have to support the answer to the challenge. Are your claims clear? Is the evidence reliable? Is the evidence appropriate to support the claims? How do you explain the results? 5 1/28/10 Final Reflections CHEM 054 What did you learn from doing your experiment? How would you improve what you did? How have your ideas changed as a result of this lab? What do you not completely understand? What new questions do you have? 6 ...
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This note was uploaded on 05/20/2010 for the course CHEM 054 taught by Professor Kozub during the Spring '08 term at UPenn.

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