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Today: Conclusion of Distillation/GC Introduction to Exp.4: Steam Distillation. IR

Today: Conclusion of Distillation/GC Introduction to Exp.4: Steam Distillation. IR. Simple & Fractional Distillation Curve. GC conditions for your EA and EP Analysis:. Sample injection volume: 0.5 mL. GC column: 15 m x 0.53 mm (I.D.) PhMe-silicone stationary phase, Rtx-50 column.

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Today: Conclusion of Distillation/GC Introduction to Exp.4: Steam Distillation. IR

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  1. Today:Conclusion ofDistillation/GC Introduction to Exp.4: Steam Distillation. IR

  2. Simple & Fractional Distillation Curve

  3. GC conditions for your EA and EP Analysis: Sample injection volume: 0.5 mL GC column: 15 m x 0.53 mm (I.D.) PhMe-silicone stationary phase, Rtx-50 column Initial oven temperature = 35oC Initial time = 0.75 min Temperature ramp = 35oC/min Final Temperature = 70oC Final time = 1.0 min Column head pressure = 20 psi or more (He as Mobile Phase) Injector Temperature = 225oC Detector Temperature = 250oC Detector: thermal conductivity (TCD)

  4. GC Chromatogram solvent RTAreaTypeWidth Area% (min) .210 333265 12.35 .506 1103207 40.88 1.061 1261972 46.77 EA EP Area ratio = mole ratio AEA/ AEP = nEA/nEP

  5. Task: Determine the amount of EA as mole % EA in sample S1 and also in sample F1 Step 1: analyze the standard mixture (50:50 v/v) of EA and EP for calibration of the GC instrument AEA = nEA x C 1 where k = C AEP nEP A = GC peak Area calculate n = moles

  6. Step2:Calculate the mole ratio of your sampleusing the correction factor obtained from the standard nEA for samples S1 and F1 nEP nEA AEA k x = nEP AEP Mole ratio →mole fraction → mole %

  7. Exp.4:Steam Distillation. IR

  8. Exp. 4: Isolation of a Natural Product Eugenol A “phenolic”. Caryophyllene Eugenol Acetate

  9. Steam Distillation • What types of mixtures can be separated by steam distillation? • The vapor pressure of water at 99oC is 733 torr. What is the vapor pressure of eugenol that codistills at this temperature? • During a steam distillation the mole ratio of two immiscible liquids is equal to the ratio of ...... ? n1/n2 = Po1/Po2

  10. Steam Distillation Dalton’s Law: P1V1 = n1RT1 and P2V2 = n2RT2 V1 = V2 and T1 = T2 n = moles, P1V1 = n1RT1 thereforen1 =P1 P2V2 n2RT2 n2 P2 where 1= water and 2 =compound steam-distilled

  11. Steam Distillation n1/n2 = Po1/Po2 (mass1/MW1) / (mass2/MW2) = Po1/Po2 Steam distillation problem: Benzene and water mixture boils at 69oC. The MW of benzene is 78.11. MW of water is 18.01 How many grams of water are required to steam distil 1 gram of benzene?

  12. Use this Table 6.1 for Interpolation

  13. Steam Distillation Which of the following boiling points are EQUAL TO 100 degrees C, which are BELOW, and which are ABOVE ? • A water - eugenol mixture • A water- acetic acid mixture (bp. of pure acetic acid: 120 degrees C; it is miscible with water) • A sand-water mixture • A solution of NaCl in water

  14. Direct Steam Distillation Set-up Macro-scale Thermometer Separatory Funnel water 150 mL water & 7g Clove buds Ice bath H2O Bunsen burner Use a lab-jack

  15. Liquid-Liquid Extraction of steam distillate with methylene chloride Which layer is methylene chloride (CH2Cl2)? Which layer is going to contain the eugenol? Aqu. layer CH2Cl2

  16. Liquid-Liquid Extraction Anhydrous Na2SO4 Plug of cotton “Tare” 50-mL E-flask with one boiling chip * * Collect both MeCl layers, then boil off solvent

  17. Infrared Spectroscopy (IR) 1) What is the approximate range of wavelengths visible to humans? And where would you find the range of IR light? How about its energy compared to visible light? 2) What are the "wavenumbers", commonly used in IR to define absorptions? 3) What type of information do we obtain from an IR spectrum? 4) How can we identify a compound from its IR, e.g. how can we know that we obtained eugenol? 5) How will your IR tell you if your eugenol sample contains impurities?

  18. Our next Experiment: Exp. 10: Caffeine!

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