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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: sharbeldam on January 17, 2020, 02:17:24 AM

Title: 3-pentanone to 3-pentanol questions
Post by: sharbeldam on January 17, 2020, 02:17:24 AM

On monday Im required to synthesize 3-pentanol via reduction of 3-pentanone with NaBH4.
I have a question regarding the materials used in (Rosenblatt handbook).

the pentanone is put in 50ml of sodium hydroxide (aq), then the sodium borohydride is added.
Why basic solution? I have read in a book that alkaline solution will make the NaBH4 more stable, but isn't usually an acid is added to protonate the alkoxide in the last step of reduction?

Also, wouldn't sodium hydroxide lead to unwanted products? for instance, can it not take an alpha hydrogen from the pentanone and lead to condensation products between two pentanones?

Thanks

Title: Re: 3-pentanone to 3-pentanol questions
Post by: hollytara on January 17, 2020, 12:59:19 PM

The reduction is much faster than the condensation reactions - particularly at room temperature.

the two ways NaBH4 reductions are done are either alkaline (as in this case) or neutral - usually in an alcoholic solvent.