Lestat
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-HO group removal
How would I go about removing a hydroxyl group from a substance and replacing with an NH2?
The procedure must not leave anything toxic behind that can't be easily removed.
And also, how to remove -HO group leaving nothing?
hmmm...
The meek arn\'t going to inherit everything, their greedy relatives will get there long before someone bothered to tell the meek than someone has
died.
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Marvin
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There are no good or safe answers to general questions and procedures usually depend more on what else is on the molecule. I would think this is
doubly true since you are probably intending to eat the result.
Maybe you would be better searching for answers at the hive? I would rather suggest reading chemistry in context cover to cover first.
Most A Level replacement methods produce ungodly mixtures with the exception of the Gabriel synthesis and go via halide replacement, but this is
difficult/wasteful to improvise.
You cant remove -OH leaving nothing. You can replace with -H (several reduction methods, alcohols are stubborn), or remove -OH and -H to produce an
alkene (typically halide replacement then alcoholic KOH) or a ketone....
[Edited on 17-5-2004 by Marvin]
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BromicAcid
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You know, quite some time ago I noticed that the reagent used in the Gabriel synthesis bears quite a resemblence to the saccrine molecule. The only
difference being the sulfur being replaced by the carbon as I remember. This has probably been discussed to death elsewhere but would these reagents
be swapable?
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Lestat
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I'm kinda new to this sort of thing, i mean organic chemistry and all, this would be my first non-inorganic/non-nuclear experiment yet, but i
have to learn somewhere and this looks like a good place to start. (almost all my chem is self taught since i "left" school)
and i'm not to sure of the procedure that you speak of BromicAcid
i would have posted a pic of the molecule, but i can't seem to post pics.
[Edited on 17-5-2004 by Lestat]
Marvin, the only reducing agent i possess is hydroquinone, which incideltally is what i am trying to reduce...
[Edited on 17-5-2004 by Lestat]
The meek arn\'t going to inherit everything, their greedy relatives will get there long before someone bothered to tell the meek than someone has
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thunderfvck
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Umm, I don't know if this will work but what the hey!
Would reacting it with NH3 do any good? Perhaps it would replace the OH, which would then take a proton away from the NH3+, leaving NH2...? I
don't know! It seems that NH3 would be the better leaving group when it initially binds to the ring, so I don't kow if the OH would even
want to go anywhere...reflux? Maybe this is too dangerous? I really don't know, others will surely enlighten me (they're all so smart!).
There's another reaction I'd like to mention in this context, although it's a bit unpractical for most of us...I don't know what
it's called, but the example I have is:
Ph-Br + KNH2 ---(NH3(l)/-33*C)--> Ph-NH2 + KBr
I realze that the bromide ion is a much better leaving group, but would it work the same way with a hydroxyl group? Also, the reaction takes place in
liquid ammonia (how exciting that must be!  ), is it merely because the reaction
is rather exothermic and may lead to an uncontrollable chain of events that could really ruin thigns?
And I don't think you'll be able to reduce one of the hydroxyl groups without reducing the other!
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frogfot
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I don't think NH3 would attack aromatic ring specially with those two activating hydroxyles..
Huh, I don't really get how the second reaction goes.. Is it sn1??
If yes, then I'd guess they wanna avoid water by using liquid NH3, to prevent phenol formation..
Btw, dunno if this'll help, but how about nitrating PhOH, separating isomers (in some way ???) and then reducing with say Fe/HCl.. sounds pretty
harmless, or?
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Lestat
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Nitrating, unfortunately, is not an opion for me having no access no nitrates/HNO3
also, are you suggesting that reaction of the hydroquinone with Aq. NH3 would produce phenol? if so that would allow me to pursue an alternate
synthesis.
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frogfot
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No, I was talking about reaction thunderfvck posted (Ph-Br + KNH2)
You can't get nitrates?
Anyway, phenole is very easy to nitrate (requires like <20% nitric or so..), so I guess KNO3/HCl would work here, somebody correct me if I'm
wrong..
getting phenole is other story..
[Edited on 17-5-2004 by frogfot]
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Lestat
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I have no access to Br or Br compounds either, and i want to MAKE phenol, not nitrate it, i aint looking for TNP
[Edited on 17-5-2004 by Lestat]
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Sandmeyer
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Lestat, the elimination-addition route using amide that frogfot mentioned proceeds via benzyne intermediate, hence it will give a mixture of isomers
should you start from an asymetric X-Ar, but it is hard to tell since you have provided no details about what compound you want to prepare.
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