Volunteers 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 me if you can help. Thank you!

Introduction to Unknowns (You have about two weeks to complete each unknown) For instructions and experimental details see Chapter 10, pp …., 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

What needs to be remembered for a good mp. measurement?Mp. for solids 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 bp.s? low bp.s?Bp. for liquids Which compounds tend to have high bp.s? low bp.s? a physical characteristic, defines a compoundRefractive index for liquids a physical characteristic, defines a compound information?Ignition test 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 NaHCO 3 ? 3. is soluble in NaOH only, not in NaHCO 3 ? 4. is soluble in dilute HCl solution? 5. is soluble only in conc H 2 SO 4 ? 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 #1 can be: Aldehyde Ketone Alcohol or Phenol Unknown #1 can be: Aldehyde Ketone Alcohol or Phenol

Aldehydes and Ketones functional 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 oxime semicarbazone 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 1 o, 2 o alcohols, amines…!) Lucas test for 3 o alcohols, 2 o 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

Aldehydes and Ketones IR: H-NMR: Preliminary tests Solubility Classification tests Derivatives Spectra

Alcohols IR: H-NMR: Exchange with D 2 O 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)