exp42004_en - NOP http:/www.oc-praktikum.de 2004 OH Ph...

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NOP http://www.oc-praktikum.de March 2006 1 2004 Diastereoselective reduction of benzoin with sodium borohydride to 1,2-diphenyl-1,2-ethanediol NaBH 4 Ph Ph O OH Ph Ph H H OH OH Ph Ph H O H H OH C 14 H 12 O 2 (212.3) (37.8) C 14 H 14 O 2 (214.3) + meso racemic Literature M. Yamada, T. Horie, M. Kawai, H. Yamamura, S. Araki, Tetrahedron 1997 , 53, 15685 Classification Reaction types and substance classes reaction of the carbonyl group in ketones, reduction, stereoselective addition ketone, alcohol, complex metal hydride Work methods stirring with magnetic stir bar, adding dropwise with an addition funnel, evaporating with rotary evaporator, filtering, recrystallizing, heating with oil bath Instruction (batch scale 10 mmol) Equipment 500 mL three-neck flask, reflux condenser, addition funnel with pressure balance, internal thermometer, bubble counter, 500 mL Erlenmeyer flask, separating funnel, 500 mL round bottom flask, heatable magnetic stirrer, magnetic stir bar, rotary evaporator, suction flask, Buechner funnel, desiccator, oil bath Substances benzoin (mp 132-134 °C) 2.13 g (10.0 mmol) sodium borohydride 0.756 g (20.0 mmol) tert -butyl methyl ether (bp 55 °C) 300 mL conc. hydrochloric acid (25%) 4 mL i c e 3 0 g sodium sulfate for drying ethanol (bp 78 °C) for recrystallizing about 3 mL
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NOP http://www.oc-praktikum.de March 2006 2 Reaction 0.756 g (20.0 mmol) sodium borohydride in 40 mL tert -butyl methyl ether are filled in a dry 500 mL three-neck flask with magnetic stir bar, internal thermometer, addition funnel and reflux condenser with bubble counter (filled i.e. with paraffin oil) and stirred for about 10 minutes until a fine suspension has formed. 2.13 g (10.0 mmol) benzoin are dissolved in an Erlenmeyer flask in 260 mL tert -butyl methyl ether under slight heating to about 30°C. The solution is cooled down to room temperature and added dropwise over an addition funnel into the reaction flask at such a rate, that the temperature of the reaction solution does not exceed
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This note was uploaded on 04/23/2010 for the course CHEM CHEM2220 taught by Professor Andreana during the Fall '10 term at Wayne State University.

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exp42004_en - NOP http:/www.oc-praktikum.de 2004 OH Ph...

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