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URGENT: Nitrating phenol - black tar-like substance? watch

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    I am trying to obtain 4-nitrophenol (p-nitrophenol) by nitrating phenol. Whilst nitrating phenol with Sodium Nitrate(V) and concentrated sulfuric acid, I was left with a black tar-like substance. I attempted to use steam distillation to separate the 2-nitrophenol (o-nitrophenol) from the 4-nitrophenol (p-nitrophenol), however what remained in the distillation flask was the black substance, which should have contained 4-nitrophenol for recrystallisation.

    What is the black substance? Have I done something wrong? Would using nitric acid be better in order to nitrate the phenol?
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    (Original post by Medulsa)
    I am trying to obtain 4-nitrophenol (p-nitrophenol) by nitrating phenol. Whilst nitrating phenol with Sodium Nitrate(V) and concentrated sulfuric acid, I was left with a black tar-like substance. I attempted to use steam distillation to separate the 2-nitrophenol (o-nitrophenol) from the 4-nitrophenol (p-nitrophenol), however what remained in the distillation flask was the black substance, which should have contained 4-nitrophenol for recrystallisation.

    What is the black substance? Have I done something wrong? Would using nitric acid be better in order to nitrate the phenol?
    These reactions are sensitive to different conditions. Reflux is necessary usually. The black stuff is probably dehydrated carbon. Remember conc sulphuric acid is not only acting to produce the electrophile NO2+ but also could act as a dehydrating agent, ie dehydrate your alcohol/any products.
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    (Original post by shengoc)
    These reactions are sensitive to different conditions. Reflux is necessary usually. The black stuff is probably dehydrated carbon. Remember conc sulphuric acid is not only acting to produce the electrophile NO2+ but also could act as a dehydrating agent, ie dehydrate your alcohol/any products.
    If I were to use nitric acid instead, what concentrations would I use etc?

    How could I set up the experiment?
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    Are you sure you don't have the nitrophenol already? When I prepared nitrophenol for my A2 coursework I had black tar stuff and some weird solution. I threw away the solution and kept the tar which was a bad mistake since the solution was 4-nitrophenol. :awesome:
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    (Original post by Medulsa)
    If I were to use nitric acid instead, what concentrations would I use etc?

    How could I set up the experiment?
    I would think that your solution actually contains mixture of nitro products. They should have different boiling points, and if you collect them under fractional distillation, you should be able to separate them; look up literature b.p of some of the possible products you might be producing.

    nitric acid should do the same thing. I mean it is conc H2SO4 that is dehydrating massively, so the black tar is most probably just carbon.
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    Hey guys, we were given this experiment as an extension but never really went over it. Could u guys give me an equation and tell me what the predicted outcome is meant to be? Thanks!
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    Hey guys, we were given this experiment as an extension but never really went over it. Could u guys give me an equation and tell me what the predicted outcome is meant to be? Thanks!

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