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Topic: IR spectrum help  (Read 16650 times)

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samven582

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IR spectrum help
« on: April 20, 2006, 08:32:39 PM »
I need help identifying this compound. I already know at 3000cm-1 and less than 3500cm-1 its a C -H. Less then 3000cm-1 must be of C-H alkane. Thats pretty much all I have identify. What I really need help is identifying the rest andnaming the compound. Any help would be appericated


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Offline lemonoman

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Re: IR spectrum help
« Reply #1 on: April 20, 2006, 08:40:15 PM »
Only one problem...IR spectra can't give you full compound identification.  It is only really useful for identifying the function groups that are present on the molecule.  You have identified the C-H region of the spectrum (a little less than 3000 cm-1) correctly.  There are a few other unique bands here as well...
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Offline mike

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Re: IR spectrum help
« Reply #2 on: April 20, 2006, 08:42:19 PM »
Are you given the molecular formula?
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samven582

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Re: IR spectrum help
« Reply #3 on: April 20, 2006, 08:51:12 PM »
Quote from: mike on April 20, 2006, 08:42:19 PM
Are you given the molecular formula?

no. The molecular forumla is not given  :(.
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Offline mike

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Re: IR spectrum help
« Reply #4 on: April 20, 2006, 09:03:11 PM »
Looks like there is a carbonyl C=O around 1700
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Offline wereworm73

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Re: IR spectrum help
« Reply #5 on: April 20, 2006, 09:49:32 PM »
I think you might have a primary amine.  The sharp absorption band at about 3300 cm-1 suggests a N-H stretch while the one around 1600 cm-1 suggests a NH2 bending.
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samven582

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Re: IR spectrum help
« Reply #6 on: April 20, 2006, 09:59:33 PM »
"I think you might have a primary amine.  The sharp absorption band at about 3300 cm-1 suggests a N-H stretch while the one around 1600 cm-1 suggests a NH2 bending"

I was thinking the same thing but I wasn't sure  :-\. Do you guys think there is a c=c or a c=o at 1800cm-1 ?
« Last Edit: April 20, 2006, 10:10:35 PM by samven582 »
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Offline mike

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Re: IR spectrum help
« Reply #7 on: April 20, 2006, 10:10:43 PM »
Maybe C=C at around 1600
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Offline letk0

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Re: IR spectrum help
« Reply #8 on: April 20, 2006, 11:06:59 PM »
It looks like there is an aromatic ring also.  I agree that there is a primary amine because no asymmetric stretch present.
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Offline AWK

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Re: IR spectrum help
« Reply #9 on: April 21, 2006, 03:55:57 AM »
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samven582

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Re: IR spectrum help
« Reply #10 on: April 21, 2006, 09:47:06 AM »
Quote from: AWK on April 21, 2006, 03:55:57 AM
Check your assignment with
http://www.aist.go.jp/RIODB/SDBS/cgi-bin/cre_index.cgi

yes I have tried that website but unfortually since I don't know the name of the compound I can't use it.
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samven582

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Re: IR spectrum help
« Reply #11 on: April 21, 2006, 10:01:48 AM »
Quote from: letk0 on April 20, 2006, 11:06:59 PM
It looks like there is an aromatic ring also.  I agree that there is a primary amine because no asymmetric stretch present.

at what range do you see a aromatic ring?
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Offline AWK

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Re: IR spectrum help
« Reply #12 on: April 21, 2006, 10:16:45 AM »
I meant you tentatively assign compound, eg aspirin, and check it in this database
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samven582

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Re: IR spectrum help
« Reply #13 on: April 21, 2006, 10:25:58 AM »
Quote from: AWK on April 21, 2006, 10:16:45 AM
I meant you tentatively assign compound, eg aspirin, and check it in this database

what kind of compound should I enter in this database?
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Offline lemonoman

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Re: IR spectrum help
« Reply #14 on: April 21, 2006, 03:25:40 PM »
Quote from: wereworm73 on April 20, 2006, 09:49:32 PM
I think you might have a primary amine.  The sharp absorption band at about 3300 cm-1 suggests a N-H stretch while the one around 1600 cm-1 suggests a NH2 bending.

Quote from: samven582 on April 20, 2006, 09:59:33 PM
I was thinking the same thing but I wasn't sure  :-\.

I might disagree...I was always taught that a single band in this region implied a secondary amine, because there's a single N-H stretch...
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