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.)

Unknown #1Unknown #1can be:can be:

Aldehyde Aldehyde KetoneKetoneAlcoholAlcohol

or or PhenolPhenol

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

Phenols Sample Compound: Phenol

IR

H-NMR

Next time (after Spring Break) :

Unknown 1 (cont.)

Unknown #2:

Carboxylic Acid, Ester, Amide, Amine

(Cl, Br, nitro)