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General organic chemistry-acidity.

  1. Dec 14, 2016 #1
    1. The problem statement, all variables and given/known data
    In mfcd00007137-medium.png is more acidic than images?q=tbn:ANd9GcT75cX0p0PJDN6DLbg4OknmfSJ-VgSx530pLeEXzymVuUJCSFfs.png but In 300px-4-Nitrophenol_acsv.svg.png (para nitro phenol) is more acidic than mfcd00011688-medium.png (ortho nitro phenol) why?

    2. Relevant equations
    in ortho nitro benzoic acid due to -I and -M effect it is more acidic than it's para species (-I effect more in ortho position) .

    3. The attempt at a solution
    In the latter compounds, due to intra molecular H-bonding, para compound is more acidic than that of the ortho compound. my doubt is in ortho nitro benzoic acid, isn't there any intra molecular H-bonding cause a carboxylic acid can form H-bonding so does the nitro compound. please solve my query :/
     
  2. jcsd
  3. Dec 18, 2016 #2

    Ygggdrasil

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    Science Advisor

    For o-nitro benzoic acid and o-nitro phenol, try drawing out all the bonds (including N-O and O-H bonds) to see what the intramolecular hydrogen bonding looks like. You may see a problem with o-nitrobenzoic acid but not o-nitro phenol.
     
  4. Dec 20, 2016 #3
    sorry i don't understand..please explain further :/
     
  5. Dec 20, 2016 #4

    Borek

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    Staff: Mentor

    Have you tried to draw what Ygg suggested?
     
  6. Dec 20, 2016 #5
    5TXTl.gif ok..this ortho nitro benzoic acid. there is this unwanted -ve sign here. main-qimg-53eee499d40b785efeb800e853e2f5b9?convert_to_webp=true.gif where as here in ortho nitro phenol, it could easily form intramolecular H-bonding...sorry! still, i didnt get the point! do explain me! it would be of great help :)
     
  7. Dec 20, 2016 #6

    Ygggdrasil

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    For the nitro benzoic acid, draw the O-H bond. Also, keep in mind the preferred angles for each bond. You should see the problem.

    If you're still not getting it, try building a model of you have a model kit.
     
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