Aldehydes and Ketones

Topics: Ethanol, Alcohol, Aldehyde Pages: 4 (868 words) Published: June 27, 2013

Aldehydes and Ketones have certain characteristics in common. However, both couldn’t exist in the same compound. Some test for the presence of aldehyde was made for this experiment. These tests includes Tollen’s test, Benedict’s Test, 2-4-dinitrophenylhydrazine and Schiff’s test.

All the tests conduted yielded same results, that is, formalin and benzaldehyde are aldehyde-containing compounds while acetone is a ketone. On the other hand, effect of acid concentration on the addition of 2-4-dinitrophenylhydrazine yielded precipitate according to the concentration of the acids used. The 0.1M HCl, 0.1M acetic acid, 1.0M HCl yielded precipitate after 4 minutes, 5 minute and 6 minutes respectively.

Aldehydes and ketones are both carbonyl-containing compounds. The said groups are very widely occurring in nature. Most of them have pleasant odor flavour that’s why they are widely used in soap-making and are commonly used as flavouring agent.*

Aldehyde has boiling points near room temperature at around (20○C). Aldehyde have formaldehyde as its simplest form. Ketones, on the other hand has acetone as its simplest form.


Reaction with 2,4-dinitrophenyldrazine
In three separate test tubes, 1 ml each of 95% ethyl alcohol was placed. To one tube 2 drops of acetone was added and to the other two, 2 drops of benzaldehyde was added. Afterwards, 1 ml of of 2,4-dinitrophenyldrazine was added to each of the three test tubes.

Tollen’s test
In three test tubes, 1 ml of Tollen’s reagent was placed separately. To one tube, a drop of formalin was added; to the other, a drop of acetone was added; and to the other a drop of benzaldehyde was added. The solutions were mixed thoroughly. Since there was no reaction at room temperature, the solutions were placed in hot water bath .

Schiff’s test
In three test tubes, 5 drops of Schiff’s reagent was placed separately. To one tube, a drop of formalin was added,...

References: Corporation, 2008.
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