1. Today: Conclusion of Distillation/GC Introduction to Exp
Today: Conclusion of Distillation/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. Area ratio = mole ratio AEA/ AEP = nEA/nEP GC Chromatogram solvent
RT Area Type Width Area%
(min) 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. Mole ratio → mole fraction → mole %
Step 2: Calculate the mole ratio of your sample using 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 = n1RT and P2V2 = n2RT2
V1 = V2 and T1 = T n = moles,
P1V1 = n1RT1 therefore n1 = P1
P2V n2RT n P2
where 1= water and 2 =compound steam-distilled

11. (mass1/MW1) / (mass2/MW2) = Po1/Po2
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 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 & g 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!