H1 NMR Help
So there's a question with the H1 NMR Spectrum:
The mark scheme says the peak at 7.2 is from a benzene ring with 5 H's. Doesn't the big number of peaks mean there should be a lot of adjacent protons? But the mark scheme says the final structure is:
But there are no adjacent protons on the benzene ring?
What am I missing?;(
Thanks!
The mark scheme says the peak at 7.2 is from a benzene ring with 5 H's. Doesn't the big number of peaks mean there should be a lot of adjacent protons? But the mark scheme says the final structure is:
Attachment not found
But there are no adjacent protons on the benzene ring?
What am I missing?;(
Thanks!
The fine structure at 7.2 is characteristic of benzene protons, the splitting doesnt come from adjacent protons for reasons you'll learn if you do degree level chemistry. All you need to know is that when you get a high ppm jagged multiplet, you can bet your bottom dollar that there arr benzene protons.
The spitting is because the benzene ring is substituted - by having the OC(O)CH(CH3)2 group, your hydrogens on the aromatic ring aren't all magnetically equivalent; you've got three different sets of hydrogens - ortho, meta and para to the substituted group. All of these will still come out around the same position, but will couple with each other, causing the splitting and a multiplet at ~7 corresponding to the aromatic ring.
Original post by Spudgunhimself
The fine structure at 7.2 is characteristic of benzene protons, the splitting doesnt come from adjacent protons for reasons you'll learn if you do degree level chemistry. All you need to know is that when you get a high ppm jagged multiplet, you can bet your bottom dollar that there arr benzene protons.
Ahh okay, thanks
also I was wondering how the spectrum says there are 5 protons in the benzene environment but there are like 3 different proton environments on the benzene?Original post by Stiff Little Fingers
The spitting is because the benzene ring is substituted - by having the OC(O)CH(CH3)2 group, your hydrogens on the aromatic ring aren't all magnetically equivalent; you've got three different sets of hydrogens - ortho, meta and para to the substituted group. All of these will still come out around the same position, but will couple with each other, causing the splitting and a multiplet at ~7 corresponding to the aromatic ring.
Right, thank you!
Original post by white_o
So there's a question with the H1 NMR Spectrum:
The mark scheme says the peak at 7.2 is from a benzene ring with 5 H's.
The mark scheme says the peak at 7.2 is from a benzene ring with 5 H's.
It looks like Q5c on June 13 OCR A F324 (look it up), but it isn't as the OCR MS mentions the peak at 7.3.
Which exam board have you taken the Q from?
If it were OCR A, the spec says: "Candidates will be expected to identify aromatic protons from chemical shift values but will not be expected to analyse their splitting patterns." i.e. stop panicking.
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