Reactions of Carbonyls-Aldehyde/Ketone Analysis:
The carbonyl group is a rich source of many important reactions in organic chemistry, with two fundamental properties that are primarily responsible for its diverse chemistry. The first is the polarization of the. Carbon-oxygen pi bond, owing to the relatively high electro negativity.
The second property of a carbonyl function is to increase the acidity of the alpha-hydrogen atoms, which are the hydrogen’s on carbons directly attached to the carbonyl carbon. While most carbonyl functional groups share these two properties, within the carbonyl family of compounds, there are significant differences in reactivity. Aldehydes are generally more reactive than ketones and more easily oxidized. Carbonyls directly bonded to aromatic groups are generally less relative than Carbonyls that are directly bonded to alkyl substituents. In this experiment, we will perform each reaction on the known compounds that correspond to each chemical test first, to determine whether the reagents are working and to help you interpret a positive or a negative test. It is important that after the tests, the unknown sample will not be able to be unequivocally determined.
During this experiment, there were three different tests that were completed to determine what compound the unknown sample was. I started off with unknown sample #5 which was clear in color. The first test completed was the iodoform test. Once all three of the test tubes contained 2 mL of 5% NaOH and 3 drops of the unknown, 3-pentanone, or acetophenone, iodine solution was added by the drop until the yellow color of the iodine was slightly visible. The test tube containing the unknown and 3-pentanone only needed 3 drops each while acetophenone required 11 drops. The test tube containing acetophenone tested positive by forming a white/yellow precipitate at the bottom of the test tube. The unknown...
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