volunteers needed to help doing chemistry activities (“plant smells and molecules”) with...
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Volunteers neededVolunteers needed
To help doing chemistry activities (“Plant smells and molecules”)
with youngsters and their families
• Saturday, April17 (~ 10-2) ACS Earth Day event, Martinez
• Sunday, April 18 (~ 9-1) ACS at Boy Scout Jamboree, Pleasanton
Please email me if you can help.Please email me if you can help.
Thank you!Thank you!
Introduction to Unknowns(You have about two weeks to complete each unknown)
For instructions and experimental details see Chapter 10, pp.618 - …., in your Mayo text
For a list of Unknowns and their derivatives see our ERES files
Sample “Unknown” problems are in our ERES Exam Folder
1. What is typical of the molecules of compounds that have an odor?
2. Which organic compounds tend to have a "pleasant" odor? And which tend to have a "bad" odor"?
3. What characteristic features do you find in the molecule structure of organic compounds that have a color?
Unknowns Preliminary Tests pp. 618 - 626
• Mp. for solids What needs to be remembered for a good mp. measurement?What needs to be remembered for a good mp. measurement?
Which compounds tend to have high mp.s? low mp.s?Which compounds tend to have high mp.s? low mp.s?
• Bp. for liquids Which compounds tend to have high bp.s? low bp.s?Which compounds tend to have high bp.s? low bp.s?
• Refractive index for liquids a physical characteristic, defines a a physical characteristic, defines a compoundcompound
• Ignition test information?information?
• Test for unsaturation
• Beilstein test for halogen (p.626)
Preliminary Tests
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?
Solubility Tests (pp. 626 – 627)
After the Solubility tests you will do
Classification tests (specific for a certain functional group)
Once you have a reasonably good idea what your unknown could be (check ERES file),
you will prepare two
Derivatives(related solid compounds with a defined, listed mp.)
Aldehydes and Ketonesfunctional groups?
•Typical properties….
• Mp., bp., solubility…
• Preliminary tests
• Solubility
• Classification tests
• Derivatives
• Spectra
2,4-dinitrophenylhydrazone
Classification Tests for Aldehydes and Ketones
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.
• Preliminary tests
• Solubility
• Classification tests
• 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
To distinguish between aldehydes and ketones:
• Preliminary tests
• Solubility
• Classification tests
• Derivatives
• Spectra
Aldehydes and Ketones Derivatives
Imines:2,4-dinitrophenylhydrazone
oximesemicarbazone
• Preliminary tests
• Solubility
• Classification tests
• Derivatives
• Spectra
Alcohols and Phenols
Solubility distinction?
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
Alcohol and Phenol Derivatives
• with 3,5-dinitrobenzoyl chloride
• urethanes
Similarly: Naphthyl urethanes
• Preliminary tests
• Solubility
• Classification tests
• Derivatives
• Spectra
Anthocyanin Colors:Phenolic plant pigments responsible for
blue, purple, pink colors in plants. Can complex with metal ions in soil,
are pH sensitive
- glucose
Cl-
O
O
OH
HO
OH
OCH 3
OCH 3
+
Malvidinan anthocyanin in blue grapes
Aldehydes and Ketones
IR:
H-NMR:
• Preliminary tests
• Solubility
• Classification tests
• Derivatives
• Spectra
Alcohols
IR:
H-NMR:
Exchange with D2O
• Preliminary tests
• Solubility
• Classification tests
• Derivatives
• Spectra