Organic Chemistry Lab 318 Spring 2012 DUE DATES
Organic Chemistry Lab 318 Spring, 2012
DUE DATES • Today – At beginning of lab – Grignard Reaction Report – At end of lab -- copy of laboratory notebook pages for today's experiment • Next Week – Qualitative Analysis Report
The Experiment • Qualitative Analysis – Identification and characterization of unknown compounds – Chemical and spectroscopic methods • Chemical classification – “test tube” reactions that are fast and give a visual result • Spectroscopy – IR; H-NMR/C-NMR; mass spectroscopy – The unknowns are either aldehydes or ketones – You will perform chemical tests, take an IR and receive/take an NMR
Experiment Notes • Follow the instructions in the Manual and in Pavia, beginning on p. 446. • Simple distillation to purify unknown and get a b. pt. or m. pt. determination • Refractive index – remember to record room temp. • Perform “qual tests”. – Record all observations in your notebook; do not merely record “positive” or “negative”. – Do not fill in the table on the Handout – it is part of your report. – Use 1, 2 -dimethoxyethane instead of di(ethylene glycol) diethyl ether for Tollens
Experiment Notes • When you are finished with your qual tests, write a paragraph in your notebook that summarizes the results. • You then should be able to justify the conclusion that you have either an aldehyde or a ketone (and if you have a ketone, whether it is a methyl ketone or not). • After you have successfully convinced me of your conclusion (orally and in writing), you can take an IR. – (Of course, you will be able to tell whether or not you have an aldehyde by the specific IR absorptions)
Experiment Notes • Solubility test – H 2 O and conc. H 2 SO 4 – Watch for color change or heat evolution with concentrated H 2 SO 4. Positive results indicates a reaction of >C=O with H+ • 2, 4 -DNP [no reagent available!!!] Precipitate color: yellow orange red Extent of conjugation in ald/ket: unconjugated some highly
Experiment Notes • Chromic Acid – Aldehydes are easily oxidized – ketones are not orange sol’n green ppt. • Tollens Test – Aldehydes are easily oxidized – ketones are not – Show me the results of your test.
Experiment Notes • Iodoform Test • Test for methyl ketones yellow ppt • Use a large test tube. • It may take a long time, so do this test first. • Show me the results of your test.
Experiment Notes • Each student gets his/her own unknown. • You may work in groups on the known compounds (I will divide the class). • One person sets up each test for knowns and unknowns. Both people perform the tests and observe and interpret results. • Both people are responsible for the results. • DO NOT divide the work by giving one person sole responsibility for a test.
Experiment Notes • Pavia tells you what knowns to use for each test. Use them. • This should correspond to the Table that is part of the Handout (please let me know of any discrepancies). • Unknown possibilities are listed in the Manual appendix.
Experiment Notes • All waste goes into the WASTE JAR in the Hood
Experiment Notes • Clean-up: Michael Chung and Cindy Tran
- Slides: 12