From: donotsentjunk@hotmail.com   
      
   On 04/07/2015 12:49, durabol74@gmail.com wrote:   
   > On Friday, July 3, 2015 at 4:13:46 AM UTC-6, yyy378 wrote:   
   >> On 03/07/2015 14:27, durabol74@gmail.com wrote:   
   >>> This reaction takes place in methanol and slowly over 1 hour sodium   
   borohydride is stirred in. Since heat is generated I assume the sodium   
   borohydride reacts with the methanol as the reduction takes place but I am   
   unsure if this is correct? If it    
   doesn't react with the methanol it would be nice if I could dissolve the   
   sodium borohydride in methanol and use a dropping funnel. I have read that the   
   reduction can also be done with lithium aluminum hydride or sodium, which   
   might be a better way to go,    
   but I don't have much for details on these other options.   
   >>>   
   >>> Brock   
   >>>   
   >>   
   >> Sodium borohydride reacts with methanol. The reaction is completed in 90   
   >> minutes (in the presence of excess of methanol). But if you want to use   
   >> it to reduce aldehyde or ketone, whose reactions are quite fast,   
   >> methanol is typically the choice of solvent.   
   >>   
   >> LAH and sodium are stronger reducing agents. Depending on what other   
   >> functional groups are present, you may or may not be able to use them.   
   >>   
   >> Use sodium borohydride if you can because it is fast and workup is   
   >> simple. LAH very often gives an emulsion during workup.   
   >   
   > Thanks for the response. I now think I can use a dropping funnel.   
   > I've come up with this tentative procedure that I will post here   
   > for review: 2g sodium borohydride in 100ml methanol is added drop wise   
   > over 20m to 5g of the ketone in 100ml methanol, let sit 70m or add   
   > acid(acetic or HCl) until slightly acidic, evaporate or add 500ml   
   > ice water to precipitate the diol.   
   > Brock   
   >   
      
   Seems a lot of solvent to me. If you cut down the amount of solvent, the   
   reaction will run faster and you save the cost (that will become   
   important if you go to work in industry one day.)   
      
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