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Topic: selective reduction with sodium borohydride  (Read 20018 times)

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Offline Marija

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selective reduction with sodium borohydride
« 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
Thank you very much and have anice day.  ;D
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Offline nj_bartel

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Re: selective reduction with sodium borohydride
« Reply #1 on: April 25, 2009, 07:20:05 PM »
imine reduction I think

Offline ufalynn88

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Re: selective reduction with sodium borohydride
« Reply #2 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.

Offline Marija

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Re: selective reduction with sodium borohydride
« Reply #3 on: April 26, 2009, 04:54:26 AM »
So the nitro group stays unchanged? And thanks both of you for your answers. :)
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Offline nj_bartel

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Re: selective reduction with sodium borohydride
« Reply #4 on: April 26, 2009, 05:06:42 AM »
Correct.  Don't think any hydride donors will reduce a nitro group.

Offline Marija

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Re: selective reduction with sodium borohydride
« Reply #5 on: April 26, 2009, 05:26:26 AM »
I thought so, but I wasn't sure. Thanks again for your help. :)
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Offline singh.abhijitpratap

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Re: selective reduction with sodium borohydride
« Reply #6 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.

Offline nj_bartel

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Re: selective reduction with sodium borohydride
« Reply #7 on: April 27, 2009, 11:22:53 AM »
Pretty sure LAH doesn't reduce nitro groups.

Offline macman104

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Offline sjb

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Re: selective reduction with sodium borohydride
« Reply #9 on: April 27, 2009, 11:37:20 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.

Offline nj_bartel

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Re: selective reduction with sodium borohydride
« Reply #10 on: April 27, 2009, 12:41:51 PM »
Maybe it was just aromatic nitro groups I was thinking of?  Would that hold true?

Offline aldoxime_amine

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Re: selective reduction with sodium borohydride
« Reply #11 on: April 28, 2009, 12:17:58 PM »
azobenzenes with aromatic nitro compounds on treatment with LAH....(?)

Offline singh.abhijitpratap

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Re: selective reduction with sodium borohydride
« Reply #12 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.

Offline singh.abhijitpratap

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Re: selective reduction with sodium borohydride
« Reply #13 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.

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