Recrystallization microscale procedures

Analysis and Recrystallization Determine the weight and melting point of each crude product. If you know the relative amounts of benzoic acid (5) and naphthalene (7) in the original mixture, calculate the percent recovery of each compound. Recrystallize them according to the general microscale procedures provided in Section 3.2 and determine the melting points of the purified materials. 

Consult with your instructor before performing this experiment, in which you will determine the stereoselectivity of the reduction of benzoin with sodium borohydride. Follow either the Miniscale or Microscale Procedure described for reducing 9-fluorenone to reduce benzoin with sodium borohydride. but use ethanol rather than methanol as the solvent. After slowly adding 3 M HCI to decompose the excess borohydride. add enough water to adjust the solvent composition to 50% v v) ethanol and water. You may recrystallize the crude product from 50% (v v) ethanol and water. Obtain the melting point and the IR. H. and NMR spectra of the purified product for characterization. Compare these data with those for racemic and meso-hydrobenzoin to determine the identity of the product and the stereochemistry of the reduction. If authentic samples of racemic and meso-hydrobenzoin are available, determine mixed melting points to support your assignment. 

The procedures for performing dissolutions in single solvents at the mini- and microscales differ slightly, as described below. Discussion of the strategies for using mixed solvents for recrystallizations is presented as well. 

List the steps in the systematic procedure for microscale recrystallization, briefly explaining the purpose of each step. 

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