Sodium Borohydride Reduction of Benzoin

Experimental Procedure:

            First, add benzoin (0.5g) and ethanol (4mL) to an Erlenmeyer flask (25mL) swirling at room temperature until it is all dissolved. Add sodium borohydride (0.1g) using a micro spatula in small amounts for 5 minutes (swirl for addition 20 minutes at room temperature). Cool the mixture using ice bath, add water (5mL) after and 6M HCl (0.3mL). Wait 15 minutes to add more water (2.5mL). Then collect the product using vacuum filtration (reserve 1-2mg for TLC analysis) after 15 minutes. Recrystallize from acetone, using 25 mL flask. Let it all dry and come back for evening hours. MP, yield %, and mass needs to be determined. Dissolve a small amount of benzoin, using recrystallized product and reserved crude product in ethyl acetate. Spot 2 TLC plates, with starting material, reserved crude product, recrystallized product, and a spot that contains both in the middle. Run the TLC plates in 9:1 CH­­₂Cl₂: ethanol. Add eluent to TLC developing chamber, use tweezers to carefully put the TLC plate in the chamber and screw the cap. Allow the solvent to run from the baseline to about 1cm from the top. Remove the TLC plate when it is ready marking the solvent from it and allow it to dry. Use UV light and mark them once it is all dry. Tape the plates on a sheet of the lab notebook paper or take a picture and draw into the lab notebook.