Miniscale experiments

For many experiments, it is necessary to remove the excess solvents to recover the product. Although an Erlenmeyer flask or beaker containing the solution could simply be left unstoppered in the hood until the solvent has evaporated, this is rather slow and impractical unless you like spending excessive amounts of time in the laboratory. A variety of techniques may be used to speed the process. Several other methods for removing solvents in miniscale experiments are shown in Figure 2.71, and the related microscale techniques are illustrated in Figure 2.72. 

A.M. Schoffstall, B.A. Gaddis, M.L. Druelinger and M. Druelinger, Organic Microscale and Miniscale Laboratory Experiments, McGraw Hill, Boston, 2000. ISBN 0072375493. 

Modern Projects and Experiments in Organic Chemistry Miniscale Standard Taper Microscale [15] 13 43 13... 

Mohrig J R, Hammond C N, Schatz P F, Morrill T C (2003) Modern projects and experiments in organic chemistry Miniscale and standard taper microscale 2nd ed. WH Freeman New York ... 

Schoffstall A M, Gaddis B A, Uruclingcr M L (2004) Microscale and miniscale organic chemistry laboratory experiments 2nd ed. McGraw Hill New York... 

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. 

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