Questions of the Day:
Which test allows you to distinguish between
1) an aldehyde and a ketone?
2) an aldehyde and a primary alcohol?
3) an alcohol and a phenol?
Today:
“Unknowns”
- Review of Preliminary Tests and Solubilities
Unknown #1:
- Classification tests and derivatives for:
Aldehydes and Ketones
Alcohols and Phenols
Family Science Night
Volunteers
meet after next
Tuesday’s Lablecture
Next time:
Unknown #2:
Carboxylic Acids, Esters, Amides. Amines.
Preliminary Tests
Aldehydes and Ketones
Alcohols and Phenols
•
Mp. for solids (What needs to be remembered for a good mp.measurement?)
•
Bp. for liquids
•
Refractive index for liquids a physical characteristic, defines a compound
•
Ignition test information?
•
Test for unsaturation
•
Beilstein test for halogen (p.626)
Solubility Tests
(pp. 626 – 627)
What type of information do you get if your unknown
1. is soluble in water?
2. is soluble in NaOH and in NaHCO3?
3. is soluble in NaOH only, not in NaHCO3?
4. is soluble in dilute HCl solution?
5. is soluble only in conc H2SO4?
6. is not soluble in any of the above solvents?
Aldehydes and Ketones
functional group?
• Preliminary tests
• Solubility
• Classification tests
• Derivatives
• Spectra
•Typical properties….
• Mp., bp., solubility…
Aldehydes and Ketones
IR:
• Preliminary tests
• Solubility
• Classification tests
• Derivatives
• Spectra
H-NMR:
Classification Tests for
Aldehydes and Ketones
• Preliminary tests
• Solubility
• Classification tests
• Derivatives
2,4-dinitrophenylhydrazone
• Spectra
also a good derivative!
1. What are desirable properties of a derivative?
2. What is the purpose of preparing a derivative?
→Prepare two good derivatives of each unknown.
Recrystallize from ethanol/water.
Aldehydes and Ketones
• Preliminary tests
To distinguish between aldehydes and ketones:
• Classification tests
• Solubility
• Derivatives
• Spectra
• Tollens Test:
• Jones (chromic acid): check reagent! Test is also positive for …..?
• Schiff reagent: check reagent!
Always do with a known compound to compare!
Aldehydes and Ketones
Derivatives
• Preliminary tests
• Solubility
• Classification tests
• Derivatives
Imines:
2,4-dinitrophenylhydrazone
oxime
semicarbazone
• Spectra
Alcohols and Phenols
Solubility distinction?
• Preliminary tests
• Solubility
• Classification tests
• Derivatives
• Spectra
Solubility:
Alcohols: “neutral”;
Phenols: very weak acids, pKa around 10, except nitrophenols!
Classification tests:
• Jones (also positive with 1o, 2o alcohols, amines…!)
• Lucas test for 3o alcohols, 2o alcohols (slow):
• Phenols only: Complexation with Fe 3+
• Preliminary tests
• Solubility
• Classification tests
• Derivatives
• Spectra
IR:
H-NMR:
Exchange with
D2O
Alcohols
Phenols
Sample Compound: Phenol
IR
H-NMR
• Preliminary tests
Alcohol and Phenol Derivatives
• Solubility
• Classification tests
• Derivatives
• with 3,5-dinitrobenzoyl chloride
• Spectra
• urethanes
Similarly: Naphthyl urethanes
OCH 3
OH
Anthocyanin Colors:
Phenolic plant pigments responsible for
blue, purple, pink colors in plants. HO
Can complex with metal ions in soil,
are pH sensitive
+
O
OCH 3
O - glucose
OH
Cl
Malvidin
an anthocyanin in blue grapes
-
Next time:
Unknown #2:
• Carboxylic Acids, Esters, Amides
• Amines
• (Cl, Br, nitro)
MiniQuiz on today’s class!