Reduction of 1-amino-4-nitrobenzene to form 1,4-diaminobenzene

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username1160642
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Pigster
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Which exam board?
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User1686961
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(Original post by sbzk101)
Hi guys. I have a question about the reduction of 1-amino-4-nitrobenzene to form 1,4-diaminobenzene. It's a reduction reaction, so I thought that LiAlH4 should be enough to reduce one of the nitro groups to an amino group. But the mark scheme disallows this and specifies "Sn (or Fe) / HCl or Ni / H2 (1)
NOT LiAlH4 NaBH4".
Any idea why LiAlH4, which can ordinarily be used to reduce nitrobenzene, can't be used in this case?
reduction. Sn/ HCL concentrated. Heated under reflux. HCL is then neutralized. Although you only need to know the sn/hcl bit. My board is OCR this is what i've memorized.

LiAlH4 is used to reduce carbonyl compounds same with NaBH4 hence it cant be used to reduce the nitro group. Therefore your answer is incorrect.
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Pigster
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Wikipedia says that azos tend to form with metal hydrides.
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User1686961
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(Original post by sbzk101)
I realise that you do generally use tin and concentrated HCl under reflux, but why can you not use LiAlH4?
Because LiAlH4 is used to reduce carbonyl compounds. Ie Reducing a ketone to secondary alcohol etc. It is NOT used to reduce nitro to amine. As stated in my earlier response.
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Hayley Williams
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(Original post by sbzk101)
Hi guys. I have a question about the reduction of 1-amino-4-nitrobenzene to form 1,4-diaminobenzene. It's a reduction reaction, so I thought that LiAlH4 should be enough to reduce one of the nitro groups to an amino group. But the mark scheme disallows this and specifies "Sn (or Fe) / HCl or Ni / H2 (1)
NOT LiAlH4 NaBH4".
Any idea why LiAlH4, which can ordinarily be used to reduce nitrobenzene, can't be used in this case?
it is used for reduced carbonyls, right? I've never heard of using this reagent only sn and conc hcl for the formation on amino groups from nitro groups
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(Original post by sbzk101)
That's not much of an explanation - "It is because it is". I was wondering if there was an explanation in terms of the actual chemistry involved, that's all - i.e. why it can be used in one case but not in the other. Might be because one method is 'better' at reducing or something like that, idk . I mean, they're both reduction reactions.
Well sorry for that as its no within the A-Level syllabus so there is no need to know it. Im sure there is a valid reason but we don't need to know
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