MP and recrystallization Procedure PDF

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Organic Chemistry 1 Experiment 1 Lab Procedure Melting Point and Recrystallization...

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Recrystallization and MP | Beatrix Aukszi

Exp 1: Simple recrystallization and simple un-evacuated melting point determination of benzoic acid Background information: The experiment focuses on two basic concepts: purification and characterization of compounds. Microscale protocol will be followed. Please read and reference the following pages in the Gilbert lab manual: For techniques: Ch. 2 For the purification steps: Ch. 3.2, Part B1, B5. For the characterization steps: Ch. 3.3B Procedure: Students will run a total of 2 trials with benzoic acid testing different solvents. The following is a short version of the full protocol, just to guide you in how to put it together. Trial 1: Benzoic acid w/ H20 should include the following steps: 1. Weigh the benzoic acid into a 25mL Erlenmeyer flask. 2. Dissolve the compound. Once the compound completely dissolved set it aside on a piece of Kim Wipes to cool to room temperature. 3. Put Erlenmeyer flask with solution into an ice bath to allow crystals form. 4. Setup the vacuum filtration with Hirsch funnel, and collect the crystals via filtration. 5. Allow the crystals to dry completely before measuring the recovered mass. 6. Set the compound aside for melting point determination. Trial 2: Benzoic acid with methanol/ H20 solvent system: 1. Weigh the benzoic acid into a 25mL Erlenmeyer flask. 2. Preheat methanol. Dissolve the compound completely in preheated methanol. Count and record the number of drops that dissolution required. 3. Once the compound completely dissolved add room temperature DI water drop-wise until some cloudiness occurs. Count and record the number of drops that reaching cloudiness required. 4. Then set the flask aside on a piece of Kim Wipes to cool to room temperature. 5. Put Erlenmeyer flask with the solution into an ice bath to allow crystals form. 6. Setup the vacuum filtration with Hirsch funnel, and collect the crystals via filtration. 7. Allow the crystals to dry completely before measuring the recovered mass. 8. Set the compound aside for melting point determination. Melting point determination: (THIS IS NOT WHAT YOUR PRELAB SHOULD HAVE. FIND THE PROPER STEP-WISE PROTOCOL AND WRITE IT INTO YOUR PRE-LAB) 1. Follow the lab manual’s protocol to pack a capillary tube with each of the purified samples. 2. Carry out the melting point determination according to protocol, and to your instructor’s demonstration. The recrystallization part was detailed, due to the deviations and different compound use. The Melting point determination will be according to the manual’s simple un-evacuated melting point determination. Write it out in detail....