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. Your unknown mixture (note its number!)
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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
(note its number!)
a carboxylic acid, a base (aromatic amine), and a neutral organic compound
determined by their melting points
Melting point ranges …
You will prepare a solid derivative and determine its melting point to identify your amine.
What are desirable properties of a derivative?
determined by their IRWhat are we looking for in an IR?
Partitioning between aqueous and ether layer
Which one is the ether layer?
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
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 ?
Benzoyl chloride is an irritating liquid with a sharp pungent odor. Exothermic reaction with water.
Wear safety glasses, gloves, use hood!
m.p. 163 C
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