Transcript Unknowns
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!