Grignard Reaction Lab

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In order to examine the processes of Grignard reactions, a Grignard reagent was generated using bromobenzene and the Grignard reagent produced underwent a nucleophilic acyl substitution. The resulting product was expected to be triphenylmethanol. The efficiency of the production of triphenylmethanol was examined using several tests. The following tests were used to analyze the product: TLC, IR spectroscopy, percent yield, and melting point determination. To develop a Grignard reagent, bromobenzene was reacted with diethyl ether and magnesium turnings. This reaction mixture was refluxed several times. In order to produce triphenylmethanol, a mixture of benzophenone and ether was prepared and then added to the Grignard reagent that was prepared earlier. This reaction mixture was refluxed. The …show more content…
The product revealed three spots with unique Rf values. Two of the spots for the product matched the Rf values for benzophenone and triphenylmethanol, those Rf values being 0.52 and 0.37, respectively. The presence of a benzophenone spot on the product indicates that not all of the benzophenone was reacted and remained as an impurity in the final product. The third spot had an Rf value of 0.81. This third spot indicates another unknown impurity in the final product. Since there is no other Rf value to compare the third spot to, there is no way to know what compound it is indicating. The IR spectroscopy results, much like the results for TLC, show some triphenylmethanol product was generated and some impurities were present. The peak at 3400 cm-1 indicates an alcohol functional group which correlates with the structure of triphenylmethanol. The peak at 3020 cm-1 indicates an alkene group which could be seen in triphenylmethanol or benzophenone. The final peak at 1720 cm-1 indicates a carbonyl which would only be present in benzophenone. This is a clear indication of impurities present in the final
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