Week8sacch - 3804 12/1/07 Week #8 Experiment Substitution...

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3804 12/1/07 Week #8 Experiment Substitution Reaction with an Ambident Nucleopile (Alkylation of Soluble Saccharin) Abstract: In this experiment, sodium saccharin was reacted with iodoethane in the solvent DMF to undergo a nucleophilic substitution of an electrophilic alkyl halide. This was determined to be a S N 2 reaction due to the strength of the nucleophiles, the polar aprotic solvent, and the presence of a primary alkyl halide. Gas chromatography demonstrated that N- ethylsaccharide was the predominate isomer with 92.929% composition of the total mixture. This then lead to the conclusion that this was a thermodynamically controlled reaction, since the more stable product was favored at vigorous, high temperature conditions. The melting point analysis demonstrated that the product mixture was impure by having a broad range of 23°C. The 1 H NMR was not specific to this product, but demonstrated that more N isomer should be produced, and confirmed that this was a thermodynamically controlled S N 2 reaction. S N - Na + O O O I S N O O O S N O O O + + DMF Mol. Wt.: 205.17 Mol. Wt.: 155.97 Mol. Wt.: 211.24 Mol. Wt.: 211.24 Sodium Saccharinate Iodoethane N-ethylsaccharin O-ethylsaccharin Techniques Used: Vaccum Filtration Melting Point Analysis – Thomas Hoover Apparatus Automatic Pipette 1 H NMR Gas Chromatography (new) Gas chromatography was conducted to determine the purity of the isolated product. In gas chromatography a length of tubing is packed with an immobile support phase, which has characteristic absorption properties that allow interaction with the injected gases. In this experiment, different saccharin derivatives were separated on a capillary column packed with an inert wax. One derivative was more polar; therefore, it interacted strongly with the immobile support, which caused retention on the column and the separation of the saccharin derivatives. The percent composition of the derivatives in the mixture was listed in the Area Percent Report obtained from the gas chromatography. Experimental Procedure: For this experiment, the procedure outlined in the Chem 211 Lab Manual was followed, with the following exceptions. Instead of adding a mmol of sodium saccharin into the conical vial, 0.2240g were added. This solid dissolved, so the warm water bath was not
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3804 12/1/07 necessary before the addition of the iodoethane. The iodoethane was not added via an auomatic pipette, but through disposable pipettes, so approximately 75µL of iodoethane was added to the conical vial. The mixture was placed in the warm water bath for 9 minutes and 23 seconds; however, a thermometer was not used to gauge the temperature
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Week8sacch - 3804 12/1/07 Week #8 Experiment Substitution...

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