CHM 226 - Tech 715 - Reducing Benzil

CHM 226 - Tech 715 - Reducing Benzil - TECH 715 Reducing...

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TECH 715 Reducing Benzil Using Sodium Borohydride INTRODUCTION Reduction occurs when an organic molecule either gains a hydrogen or looses an oxygen. Lithium aluminum hydride (LiAlH 4 ) and Sodium Borohydride (NaBH 4 ) are the most common reducing agents in these types of reactions. In this lab sodium borohydride will be used to reduce benzyl which can produce five separate products. Mixture melting point, thin-layer chromatography, and infrared spectroscopy will be used to distinguish between two out of the possible five products; meso -hydrobenzoin and (+)-benzoin. PROCEDURE The first step in this lab is to recrystalization benzil. 100 mg of benzil was placed into a 10 mL Erlenmeyer flask and 1.0 mL of 95% ethanol was added. The solution was heated for 3-4 minutes on a sand bath at about 60 o C. The flask was removed and cooled to room temp. It was then placed in an ice bath to initiate recrystalization. While still in the ice bath, about 20 mg of NaBH 4 was added. The solution was removed from the ice bath and mixed by swirling for about 3 minutes. The solution sat at room temp for 10 minutes and then 1.0 mL of distilled water was added and heated to a boiling point of about 75 o C. A separate amount of distilled water was also heated. Then, 30-40 drops of the heated distilled water was added until the solution became cloudy develops. The solution was then placed into an ice bath for five minutes; along with a separate amount of distilled water. The product was collected in a Hirsch funnel using vacuum filtration. 1 mL portions of cooled distilled water were added to wash the remaining product. The remaining product was allowed to dry, and then it was weighed. Mixture melting point was measured by separating two piles of about 5 mg of the
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CHM 226 - Tech 715 - Reducing Benzil - TECH 715 Reducing...

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