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Topic: IR spectrum of 4'-acetanilide  (Read 12778 times)

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Offline Mizushina Rena

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IR spectrum of 4'-acetanilide
« on: December 13, 2015, 12:42:26 PM »
Hello,

this is my first post. I've problems with my IR spectra: I've used acetanilide with the quad amount of sulfuric acid and the equivalent amount of nitric acid to synthesize 4-acetanilide. It's a yellow solid. The IR spectrum was made with KBr.



I'm not sure but: I suppose 3272,38 cm-1 is the N-H-streching vibration. The peak 1677,01 should be the C=O-bond. The peak 3090,98 should be C=C-H-bond of the aromatic system. I cannot found more peaks because it's very confusing.

Offline Babcock_Hall

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Re: IR spectrum of 4'-acetanilide
« Reply #1 on: December 14, 2015, 09:04:28 AM »
You might be able to find reasonable assignments for the C-C bonds of the aromatic ring.  These depend on the substitution pattern, and there are several peaks that would be expected to show up.  How much time you spend doing this might depend on how extensive the assignment you were given is (what the level of expectation is). 

Offline discodermolide

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Re: IR spectrum of 4'-acetanilide
« Reply #2 on: December 14, 2015, 11:08:59 AM »
Hello,

this is my first post. I've problems with my IR spectra: I've used acetanilide with the quad amount of sulfuric acid and the equivalent amount of nitric acid to synthesize 4-acetanilide. It's a yellow solid. The IR spectrum was made with KBr.



I'm not sure but: I suppose 3272,38 cm-1 is the N-H-streching vibration. The peak 1677,01 should be the C=O-bond. The peak 3090,98 should be C=C-H-bond of the aromatic system. I cannot found more peaks because it's very confusing.


So the compound is a nitro acetanilide, judging by your reagents. Perhaps this may make the spectrum explainable?
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Offline Mizushina Rena

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Re: IR spectrum of 4'-acetanilide
« Reply #3 on: December 14, 2015, 07:04:11 PM »
You might be able to find reasonable assignments for the C-C bonds of the aromatic ring.  These depend on the substitution pattern, and there are several peaks that would be expected to show up.  How much time you spend doing this might depend on how extensive the assignment you were given is (what the level of expectation is).

Can you explain what you mean by that? I have problems to understand that.

@discodermobile: My bad, this is the wrong structure! There must be a -NO2 grup, obviously.

Offline Babcock_Hall

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Re: IR spectrum of 4'-acetanilide
« Reply #4 on: December 15, 2015, 10:54:10 AM »
Up to four absorptions are seen between 1450-1600 cm-1.  However, you might be better off examining the C-H out of plane (oop) bending, which can be found between about 690 and 900 cm-1.  It might be possible to decide how the ring is substituted using the information from your spectrum and comparing it to a suitable table.
« Last Edit: December 15, 2015, 11:29:21 AM by Babcock_Hall »

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