1. Today: Exp.9, “Separation and Identification of an Unknown Mixture” (3 lab periods) “Qualitative analysis” This experiment includes: liquid/liquid extraction, IR, recrystallization, melting points, and other techniques you learnt this semester

2. Your unknown mixture
(note its number!)
contains:
a carboxylic acid, a base (aromatic amine), and a neutral organic compound

3. determined by their melting points
Carboxylic acids
determined by their melting points
Melting point ranges …

4. Bases: Aromatic Amines.. .. .. .. .. ..
You will prepare a solid derivative and determine its melting point to identify your amine.
What are desirable properties of a derivative?

5. determined by their IR What are we looking for in an IR?
Neutral Compounds
determined by their IR What are we looking for in an IR?

6. Liquid-Liquid Extraction
Partitioning between aqueous and ether layer
Which one is the ether layer?

7. Partition or Distribution Coefficient kp
Refer to pp. 58 – 60 in your lab text and to today’s class handout
solubility of compound A in solvent 2
solubility of compound A in solvent 1
or kp = (g/ml) organic layer / (g/ml) aqu. layer
Kp =
Question to think about…:
Assume that 100 ml of an aqueous solution of compound A is extracted twice with 100 ml of ether (using fresh ether each time).
If instead we extracted just once, but with a volume of 200 ml of ether, would we extract the same amount of A ?
(Study handout!)

8. Separation Scheme

9. Begin of Separation

10. Isolation of Carboxylic Acid
Do today

11. Separation of Neutral
Do today

12. Separation of Amine

13. Amine Derivative: Prepare only Benzanilide 2b)
Warning!
Benzoyl chloride is an irritating liquid with a sharp pungent odor. Exothermic reaction with water.
Wear safety glasses, gloves, use hood!
Benzanilide
m.p C

14. IR Spectroscopy Next Lab Lecture: IR
Your IR samples must be ready for analysis today.
Label the 50-mL E-flask with your sample with your name and section. Place a clean disposable glass pipette with a rubber bulb in this flask.
IR spectra will be ready next time
Next Lab Lecture: IR