It was an interesting experiment and definitely the longest, lasting nearly 7 hours over two lab times. It was done on November 8th and 15th. The most important requirement for this lab was that all the glassware used had to be completely dry, because the Grignard reagent (phenylmagnesium bromide) is such a strong base that it reacts with water. Even the humidity level in the lab can affect the reaction. All glassware was carefully washed and dried the week before, using a heat gun when needed:
The apparatus for the initial reaction was set up like so, and also heated to remove traces of vapor:
Then, drying tubes were packed with cotton and calcium chloride and inserted into the top of the condenser (higher part) and the addition funnel (lower part) to keep the enviroment anhydrous.
Note that the bromobenzene has already been added to the funnel. In the actual experiment, that happens after the drying tubes have been attached. Then, magnesium turnings were added to a flask at the bottom of the apparatus, and bromobenzene was added to cover them. The mixture began to react spontaneously with no additional heat. When the reaction slowed, more bromobenzene was added.
Video showing the vigorous reaction:
After all 9 mL of bromobenzene had been used up, the reaction continued for a little while with the help of a warm water bath.
The methyl benzoate was then added, as was ether, turning the mixture a reddish-punch color. Methyl benzoate, used to train drug-sniffing dogs to detect cocaine, smells like new shoes at Payless. With the help of a hot water bath, the reaction started and a solid formed.
As much solid as possible (someone next to me compared it to pumpkin pie) went into a slurry of sulfuric acid and ice, and a vigorous reaction was seen. The whole caboodle was then transferred to a seperatory funnel to remove the aqueous layer. The yellow layer was kept.
As in other experiments, sodium sulfate was added to the ether to remove water. This material comes as an anhydrous powder, and upon absorbing any water remaining in the ether it takes on the appearance of salt. Afterwards, the mixture was filtered and the ether evaporated.
This experiment leaves lab benches covered in interesting glassware:
A week later, the solid left after the ether had been evaporated was triturated (mixed) with petroleum ether. The solid turned white, and the now yellow ether was removed.
After a bit of warming, isopropyl alcohol was added to dissolve all the solid. After this mixture cooled down, crystals began to form out of solution, looking for all the world like the inside of a snowglobe.
This was then filtered, and voila - 3.224 grams of triphenylmethanol were produced.
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