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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Marija on April 25, 2009, 03:33:14 PM

Title: selective reduction with sodium borohydride
Post by: Marija on April 25, 2009, 03:33:14 PM: Hi!
I would be very grateful if someone can tell me what is the product B of the reaction showed on the picture (see the link below). http://i677.photobucket.com/albums/vv131/marija_162/Picture2.png (http://i677.photobucket.com/albums/vv131/marija_162/Picture2.png)
Thank you very much and have anice day. ;D
Title: Re: selective reduction with sodium borohydride
Post by: nj_bartel on April 25, 2009, 07:20:05 PM: imine reduction I think
Title: Re: selective reduction with sodium borohydride
Post by: ufalynn88 on April 26, 2009, 12:47:10 AM: yes ^. NaBH4 does not reduce alkenes. However, the N=H bond is polar, and a resonance structure can show the lone pair on the nitrogen and a positive charge on carbon. when this occurs, the hydride present in NaBH4 can attack this positively charged carbon while the Na+ coordinates with the negative nitrogen. upon hydrolysis, a hydrogen attaches to this nitrogen, making it an amine.
Title: Re: selective reduction with sodium borohydride
Post by: Marija on April 26, 2009, 04:54:26 AM: So the nitro group stays unchanged? And thanks both of you for your answers. :)
Title: Re: selective reduction with sodium borohydride
Post by: nj_bartel on April 26, 2009, 05:06:42 AM: Correct. Don't think any hydride donors will reduce a nitro group.
Title: Re: selective reduction with sodium borohydride
Post by: Marija on April 26, 2009, 05:26:26 AM: I thought so, but I wasn't sure. Thanks again for your help. :)
Title: Re: selective reduction with sodium borohydride
Post by: singh.abhijitpratap on April 27, 2009, 06:52:53 AM: please be aware of the fact that the nitro group can be reduced by LiAlH4 and not NaBH4.also if a carbonyl or C-N LINKAGE Iis in conjugation with a double bond which further is in conjugation with a phenyl ring then LiAlH4 reduces the double bond and the carbonyl or c-n group very effectively.
Title: Re: selective reduction with sodium borohydride
Post by: nj_bartel on April 27, 2009, 11:22:53 AM: Pretty sure LAH doesn't reduce nitro groups.
Title: Re: selective reduction with sodium borohydride
Post by: macman104 on April 27, 2009, 11:35:48 AM: http://www.organic-chemistry.org/chemicals/reductions/lithiumaluminumhydride-lah.shtm
Title: Re: selective reduction with sodium borohydride
Post by: sjb on April 27, 2009, 11:37:20 AM: Quote from: nj_bartel on April 27, 2009, 11:22:53 AM
Pretty sure LAH doesn't reduce nitro groups.

Obviously it may depend on the nature of the nitro group, but see for instance http://dx.doi.org/10.1021/ja01165a558 , or http://dx.doi.org/10.1021/jo01353a010; but to counter that http://dx.doi.org/10.1021/ja01191a057 , so it's not unknown.
Title: Re: selective reduction with sodium borohydride
Post by: nj_bartel on April 27, 2009, 12:41:51 PM: Maybe it was just aromatic nitro groups I was thinking of? Would that hold true?
Title: Re: selective reduction with sodium borohydride
Post by: aldoxime_amine on April 28, 2009, 12:17:58 PM: azobenzenes with aromatic nitro compounds on treatment with LAH....(?)
Title: Re: selective reduction with sodium borohydride
Post by: singh.abhijitpratap on April 29, 2009, 08:51:12 AM: it is common knowledge to anybody that LAH reduces nitro groups not in any conjugation with a double bond but conjugation with aryl group is an exception and LAH REDUCES IT.
Title: Re: selective reduction with sodium borohydride
Post by: singh.abhijitpratap on April 29, 2009, 08:54:00 AM: CONFUSION HAS PREVAILED OVER ME AND ONE OF U PLEASE GIVE A CONVINCING EXPLANATION TO THE QUESTION WITH APPROPRIATE REFERENCES.