Reduction Of Benzophenone With Sodium Borohydride.

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Experiment 3.1: Reduction of Benzophenone with Sodium Borohydride. Safety precaution: Sodium Borohydride Toxic & Irritant Wash spillages away with water Light Petroleum Highly Flammable Keep away from flames Ethyl Acetate Highly Flammable Keep away from flames. Residue to non-halogenated waste solvent. Ethanol Flammable Keep away from flames Residue to sink with lots of water. Benzophenone Harmful & Irritant Wash spillages away with water Hydrochloric acid Corrosive & Irritant wash spillages away with water. Introduction In this experiment, we will see the reduction of the aromatic ketone benzophenone with sodium borohydride to diphenylmethanol. The reducing agent is used in excess to ensure complete reduction of carbonyl group, and the reaction is carried out in aqueous ethanolic solution. The product is easily isolated, purified by crystalisation. By using TLC and IR spectrum, we will see the difference between benzophenone (starting material) and diphenylmethanol (final product). Experimental Procedure: Benzophenone (358mg, 2.0mmol) was dissolved in ethanol (5ml) in a 25ml round bottomed flask. The solid did not completely dissolve, so the flask was swirled with magnetic stirrer bar. In a small test tube, sodium borohydride (87mg, 2.2mmol) was dissolved in cold water (1.5ml). This solution was added drop wise to the stirred ethanolic solution of benzophenone at room temperature. After all the sodium borohydride being added, the mixture was stirred for a further 10min. Meanwhile, ice water (10ml) was mixed with concentrated hydrochloric acid (1ml) in 50ml beaker. To this the mixture of sodium borohydride and benzophenone was poured slowly into the beaker. The precipitate was collected using suction filtration and washed with 2 x 5ml portions of water. The crude product was dried at the filtration pump for

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