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Chemistry Forums for Students => Organic Chemistry Forum => Organic Spectroscopy => Topic started by: AussieKenDoll on March 18, 2019, 02:30:19 PM

Title: Determining the pi to pi antibonding UV absorptions?
Post by: AussieKenDoll on March 18, 2019, 02:30:19 PM

How do I find out if a compound expected to have pi to pi antibonding absorptions in the 200-400 nm range, just by looking at the formula of the compound?

Title: Re: Determining the pi to pi antibonding UV absorptions?
Post by: Mitch on March 18, 2019, 03:02:19 PM

Does it have pi-bonds?

Title: Re: Determining the pi to pi antibonding UV absorptions?
Post by: AussieKenDoll on March 18, 2019, 03:34:43 PM

Is having a pi bond make a compound has a pi to pi antibonding uv absorption?

Title: Re: Determining the pi to pi antibonding UV absorptions?
Post by: Babcock_Hall on March 18, 2019, 04:14:50 PM

I may be going on a tangent, but do you know what conjugated pi bonds are?  There is a relationship between the number of conjugated pi bonds and the wavelength.

Title: Re: Determining the pi to pi antibonding UV absorptions?
Post by: AussieKenDoll on March 18, 2019, 05:03:30 PM

yea i know about conjugated pi bonds! What is that relationship?

Title: Re: Determining the pi to pi antibonding UV absorptions?
Post by: Babcock_Hall on March 18, 2019, 07:38:14 PM

The difference in energy falls as the number of conjugated bonds increases.