Iodoform Reaction: The iodoform test indicates the presence of an aldehyde or ketone in which one of the groups directly attached to the carbonyl carbon is a methyl group. Given: 2,4-DNP: Positive --- Tollens: Negative --- Iodoform: Negative. Which compound(s) gave a positive test? Ethanol and methanol IV. The addition of HCN to carbonyl compounds is an … Expert Answer . Ketone. Any compounds containing the CH3C=O group or the CH3CH(OH) group give a positive result with the iodoform test. This problem has been solved! Answer: (a) intermolecular hydrogen bonding in butan-1-ol. Ethanal having one methyl group linked to the carbonyl carbon atom responds to this test. Standard Acetone. There is a large difference in the boiling points of butanal and butanal-1-oldueto (a) intermolecular hydrogen bonding in butan-1-ol (b) intermolecular hydrogen bonding in butanal (c) higher molecular mass of butan-1-ol (d) resonance shown by butanal. In this lab, you'll use the DNPH test, the Tollens' test, and the iodoform test to identify two unknown aldehydes or ketones. Acetone Benzaldehyde Butanal Cyclohexanone Unknown. Such a ketone is called a methyl ketone. See the answer. ii. The iodoform test makes a triiodo group that is a good leaving group and gives the pale yellow precipitate iodoform - a positive test. Iodoform test: Aldehydes and ketones having at least one methyl group linked to the carbonyl carbon atom responds to the iodoform test. lodoform Test. Why? In the iodoform test, the unknown is allowed to react with a mixture of excess iodine and excess hydroxide. Iodoform Test for Methyl Ketones. Procedure If the substance to be tested is water soluble, dissolve 4 drops of a liquid or an estimated 50 mg of a solid in 2 mL of water in a large test tube. Primary, secondary and tertiary alcohols III. I. Acetone and acetaldehyde II. The trichoro group would be a better leaving group but the product would be chloroform not iodoform. Question 5. Unless the iodine replaces the chlorine before the group leaves, and I don't think it would, you would not get a pale yellow precipitate! Answer. Stopper the test tube and shake vigorously. You'll use butanone and benzaldehyde as known compounds to confirm that the tests are working as expected. Record your observations. But propanal does not have a methyl group linked to the carbonyl carbon atom and thus, it does not respond to this state. Add 2 mL of 3 M sodium hydroxide and then slowly add 3 mL of the iodine solution. Previous question Next question Transcribed Image Text from this Question. Show transcribed image text. 3-Pentanone will negative results. DNPH Test for Aromatic Aldehydes and Ketones Expand. 2-pentanone will give a positive iodoform test. Benzaldehyde and butanal V. phenol and cyclohexane 2) (Acetone, propanal, benzladehyde) A. Tollens' Test.