Grignard Research Paper

Reacting specific alkyl and aryl halides with magnesium metal will result an in organomagneisum compound known as a Grignard reagent (RMgX) (Ketcha, 155). To properly create a Grignard reagent, a few rules must be follow. First, aliphatic Grignard reagents are prepared by alkyl iodides, bromides and chlorides (Ketcha, 155). Aryl and vinylic Grignard reagents are prepared normally with iodides and bromides (Ketcha, 155). Second, “anhydrous, inert and basic (polar aprotic) solvent such as diethyl ether or tetrahydrofuran (THF) is required to solvate the magnesium” (Ketcha, 155). Thirdly, there are numerous functional groups that must not be present on the organic halide molecule to make it into a Grignard reagent (Ketcha, 158). Fourth, Grignard

25 mL of a 1 M phenyl magnesium bromide in tetrahydrofuran was dispensed into the beaker by using a syringe. The resulting mixture was stirred for about 15 minutes when the purple color turned into a brown color permanently. It was then extracted first with 20 mL of dichloromethane and the bottom DCM layer containing the product was reextracted with 10 mL of dichloromethane. The final bottom layer was retained and dried with MgSO4. The drying agent was discarded when the mixture was filtered. The dichloromethane in the mixture was evaporate when the mixture was heated on a hotplate of 120 degrees C. It was heated until it stopped bubbling and a small oil layer remained. Petroleum ether (15 mL) was added, mixed, and cool in an ice bath. The product was vacuum filtrated, keeping the precipitate. The precipitate was further dried by utilizing a drying

A melting point of 130 to 135 degrees shows is over 200 degrees lower than the melting point of triphenylmethanol (360-380 degrees C). This could be due to a few reasons. One, the product was not pure. Any contamination, would it be DCM or the petroleum ether, could result in a lower temperature. What supports this possibility was the fact the product was unable to be 100% dried. This resulted in a material that was more like slightly wet clay then a solid crystal and possibly contain petroleum ether which would result in a lower melting point. Another possible reason was the final product was not, in fact, triphenylmethanol, un pure or