H NMR for salicylic acid and asprin

Chemistry discussion, revision, exam and homework help.

Announcements Posted on
IMPORTANT: You must wait until midnight (morning exams)/4.30AM (afternoon exams) to discuss Edexcel exams and until 1pm/6pm the following day for STEP and IB exams. Please read before posting, including for rules for practical and oral exams. 28-04-2013
Sign in to Reply
  1. Chemhistorian's Avatar
    • Adored and Respected Member
    • Posts: 486
    H NMR for salicylic acid and asprin
    Hi,

    Ive got 4 spectra and have to identify which are salicylic acid and asprin.

    Firstly am I right in saying that both salicylic acid and asprin have 6 H+ environments?

    Presuming I am, only 1 of the 4 spectra has 6 peaks :/

    Theres 1 with 6 peaks, 1 with 5 and the other 2 have 4 so I'm confused :/

    Any advice? Or have I missed something?

    Thanks
  2. charco's Avatar
    • Community Assistant
    • TSR Idol
    • Location: here and there
    • Posts: 9,613
    Re: H NMR for salicylic acid and asprin
    (Original post by Chemhistorian)
    Hi,

    Ive got 4 spectra and have to identify which are salicylic acid and asprin.

    Firstly am I right in saying that both salicylic acid and asprin have 6 H+ environments?

    Presuming I am, only 1 of the 4 spectra has 6 peaks :/

    Theres 1 with 6 peaks, 1 with 5 and the other 2 have 4 so I'm confused :/

    Any advice? Or have I missed something?

    Thanks
    Yes, they both have six environments.

    It's possible that the COOH proton does not show up in the acid as it's very labile and may give a very broad (and hence, flat) peak. If you are doing the NMR with a D2O shake it won't show at all.
    Last edited by charco; 13-02-2012 at 13:25.
  3. Chemhistorian's Avatar
    • Adored and Respected Member
    • Posts: 486
    Re: H NMR for salicylic acid and asprin
    (Original post by charco)
    Yes, they both have six environments.

    It's possible that the COOH proton does not show up in the acid as it's very labile and may give a very broad (and hence, flat) peak. If you are doing the NMR with a D[sb]2[/sub] shake it won't show at all.
    Thanks I went to see a lecturer about it and she said if theres any water in the sample then the COOH proton might not show up (something like that)

    Thanks
Sign in to Reply
Share this discussion:  
Article updates
Moderators

We have a brilliant team of more than 60 volunteers looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

Reputation gems:
The Reputation gems seen here indicate how well reputed the user is, red gem indicate negative reputation and green indicates a good rep.
Post rating score:
These scores show if a post has been positively or negatively rated by our members.