How to distinguish alkene double bond from benzene in IR

[virtualmaster999]

Hey everyone!

Is there a way to distinguish these two?

Ive came across a few problems where it looks like it could be either or. I know that benzene is very close to 1600, and c=c is close to 1650, but I've had some problems where it almost came in between that range.

Suggestions on how to go about this?

Thanks in advance!

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[tyjacobs]

benzene is 1500-1600 (i imagine they will give you a stretch in the 1500s)

c=c is found at 1650

so you can clearly see the difference between 1650 and a number and the 1500s

 

[DAT Destroyer]

Hey everyone!

Is there a way to distinguish these two?

Ive came across a few problems where it looks like it could be either or. I know that benzene is very close to 1600, and c=c is close to 1650, but I've had some problems where it almost came in between that range.

Suggestions on how to go about this?

Thanks in advance!

Normally you would not just get a graph with a signal in the 1600 zone without further info. HOWEVER,,,,,, A benzene ring would also show a spike around 1500 and 3030 { for the sp2 hydrogen }. Other spikes can also be noted if the aromatic compound is monosubstituted......or ortho, meta, or para-disubstituted.

Consult any organic text for a closer look.....but I doubt that you would need that kind of detail for the DAT exam.

Hope this helps.

Dr. Romano