Reaction of Aldehydes and Ketones

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Reaction of Aldehydes And Ketones Objective * Investigate some of the properties and characteristic reactions of aldehydes and ketones. * Identify the functional group in two unknown compounds through their chemical reactivity. A. DNP test for Aledehydes and Ketones. Procedure: 1. Obtain one unknown from the stock room and record its identification (ID) number in 20.5. The other unknown used in this experiment is an organic compound used as a flavoring agent. This unknown is located with the other reagents in a bottle labeled “flavoring agent.” 2. Number four clean 10-cm test tubes 1,2,3, and 4. Make sure that none of the tubes have been contaminated with acetone (which gives a positive DNP test) in the cleaning process. 3. Put 10 drops of DNP reagent into each of the four test tubes. **Safety alert**The DNP reagent should be handled carefully and kept off skin and clothing. If contact occurs, wash the contacted area immediately with cool water. Add 2 drops of acetone to tube 1,2 drops of butyraldehyde to tube 2, 2 drops of flavoring agent to tube 3, 2 drops of your unknown to tube 4. Mix well by agitationand noth the almost instantaneous formation of precipitate in tubes 1 and 2. Record all your observations for samples in table 20.1. B. Tollens Reagent. Prodedure: 1. Number 4 clean 10-cm test tubes 1,2,3, and 4. 2. Put 15 drops of dilute (6 M) sodium hydroxide (NaOH), into each test tube and allow them to stand for at least 1 minute. This prepares the glass surface for the Tollens’ test. **Safety alert** Dilute NaOH should be used carefully. It attacks the skin and is especially damaging to the eyes. If any gets on the skin or in the eyes, wash it off immediately with cool water. If the eyes are involved, also tell your lab instructor immediately. 3. After one minute, empty the NaOH from the tubes and without rinsing the

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