Identification of Unknown Ketones
Purpose:
The purpose of this experiment was to identify one ketone with Thin Layer Chromatography and one using NMR spectrometry. We will do this by making 2, 4 a DNPH derivative and checking the melting points.
Theory:
By Using specific methods of compounds detection, we can match an unknown compound with a known compound because similar compounds will display similar characteristics. In this experiment, identifications of the unknown ketone was accomplished using thin layer chromatography, melting point, and NMR spectrometry. Thin layer chromatography is very quick but sensitive way of determining the components of a mixture or a specific compound from a list of knowns. This method is the one which was utilized in the following experiment. When comparing a sample of known compounds with an unknown’s Rf values and appearance on the thin layer chromatograph these characteristics can be used to easily determine which known the unknown is. The Rf values are important in determining the more polar molecules from each other, while the color and appearance can be used to separate compounds with similar polarities. The color added by the reaction with 2,4-dinitrophneylhydrazine eliminates the need to compare colors of the different knowns with the unknown. The other method used to help determine which ketone the unknown was, was nuclear magnetic resonance spectrometry or NMR. NMR utilizes radio frequency waves to determine the number of carbons present and what they are connected to. With this information and the type of hydrogen present from the NMR, an accurate estimate of the unknown ketone can be made.
Ketone | Mol Wt | BP(deg C) | D (g/mL) | Derivative MP | 2-propanone | 58.1 | 56 | .791 | 126 | 2-butanone | 72.1 | 80 | .805 | 117 | 2-hexanone | 100.2 | 128 | .811 | 106 | 2-heptanone | 114.2 | 151 | .811 | 89 | 2-octanone | 128.2 | 173 | .819 | 58 |
Reaction/Calculations:
There were no reactions in this lab.
Known ketones:
The purpose of this experiment was to identify one ketone with Thin Layer Chromatography and one using NMR spectrometry. We will do this by making 2, 4 a DNPH derivative and checking the melting points.
Theory:
By Using specific methods of compounds detection, we can match an unknown compound with a known compound because similar compounds will display similar characteristics. In this experiment, identifications of the unknown ketone was accomplished using thin layer chromatography, melting point, and NMR spectrometry. Thin layer chromatography is very quick but sensitive way of determining the components of a mixture or a specific compound from a list of knowns. This method is the one which was utilized in the following experiment. When comparing a sample of known compounds with an unknown’s Rf values and appearance on the thin layer chromatograph these characteristics can be used to easily determine which known the unknown is. The Rf values are important in determining the more polar molecules from each other, while the color and appearance can be used to separate compounds with similar polarities. The color added by the reaction with 2,4-dinitrophneylhydrazine eliminates the need to compare colors of the different knowns with the unknown. The other method used to help determine which ketone the unknown was, was nuclear magnetic resonance spectrometry or NMR. NMR utilizes radio frequency waves to determine the number of carbons present and what they are connected to. With this information and the type of hydrogen present from the NMR, an accurate estimate of the unknown ketone can be made.
Ketone | Mol Wt | BP(deg C) | D (g/mL) | Derivative MP | 2-propanone | 58.1 | 56 | .791 | 126 | 2-butanone | 72.1 | 80 | .805 | 117 | 2-hexanone | 100.2 | 128 | .811 | 106 | 2-heptanone | 114.2 | 151 | .811 | 89 | 2-octanone | 128.2 | 173 | .819 | 58 |
Reaction/Calculations:
There were no reactions in this lab.
Known ketones: