Grignard Reagent Lab

| Reactions of Grignard Reagents with Carbonyls | | | Tuesday 1:30 | 2/28/2012 |

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Introduction This experiment explores the reactivity pattern for the addition of Grignard reagents to three different carbonyl groups: a ketone, an ester, and a carbonate. Grignard reagents are organometallic compounds that have a carbon-metal bond, such as carbon-magnesium. Grignard reagents are formed from the reaction of an alkyl, cycloalkyl, or aryl halide and magnesium metal in dry ether. The reaction is shown below in figure 1.

Figure 1: Formation of a Grignard reagent

The Carbon bonded to the metal is both a strong nucleophile and base. The Carbon with the carbanion character can participate in nucleophile reactions
Time Corrected Ret. Time 1 0.720 0 2 1.088 0.368
Chloride: 9.0 mL
Petroleum Ether: 3 mL
Diethyl Carbonate: 0.250mL
Methyl Benzoate: 0.250mL
Table 4: GC 2
There were only two peaks, the first being acetone which is the reference point, the second peak was the thriphenylmethanol. If any other compound was present in the solution, it would have appeared in the results. In all three starting materials, it still gave a GC result of only two peaks. In our run of all three solutions together, there was a third peak, the percent area of that peak was only 0.55%, the other group that ran the same solution of all three mixed together did not have the third peak. In comparison with all three different starting materials, the reagent that yielded the most products was diethyl carbonate, it yielded 64.4%. The reagent that yielded the least was methyl benzoate; it yielded 45.17%, which in reality is not that low for this experiment. It can be hypothesized that the diethyl carbonate will yield that most product of thriphenylmethanol. The way to test this would be to repeat the experiment to see if diethyl carbonate will once again yield that most