Reduction of Benzophenone and Collection of the Diphenylmethanol - Essay Example

Using gloves during the collection of the diphenylmethanol, 30g of crushed ice was placed in a 250mL beaker, and 3mL of concentrated HCL was then carefully added to the frozen water. The reaction mixture was then slowly poured into the acid in the fumehood very carefully so as to avoid foaming over. The solid product was collected by suction filtration, and the crystals were washed twice with 15mL of ice-cold water. The crystals were dried thoroughly to avoid recrystallization due to hexane being immiscible with water. Once dried, the crude product was weighed, and a crude yield was calculated. 0.1 of the crude product was then placed aside for later TLC analysis.

During the third stage, the crude product was recrystallized from hexane. Care was taken not to use too much solvent, and because hexane is flammable and has a low boiling point, the hot plate settings were kept below the maximum in order to minimize the risk of fire. The purified diphenylmethanol was then collected, and its mass was determined once dry. The percentage recovery of the recrystallization and the overall yield of the reaction were both calculated. 0.1g of the recrystallized product was kept aside for later TLC analysis. The melting point of the recrystallized material was now able to be determined at some point, or else during the next stage.

For the TLC analysis, solutions were prepared of benzophenone, crude diphenylmethanol, and recrystallized diphenylmethanol, by dissolving 0.1g of solid in 1 ml of dichloromethane. It was recommended to use vials instead of test tubes for this purpose. The eluant for developing the TLC was 1 mL of ethyl acetate dissolved in 5 mL of ligroin, and 12mL of this eluant was required. The TLC was spotted with the three solutions and the plate developed. The spots were then circled under the UV lamp, and the Rf values were calculated.