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Topic: Why is nitroacetanilide yellow?  (Read 9832 times)

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erinem

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Why is nitroacetanilide yellow?
« on: October 11, 2006, 02:21:17 PM »
I just finished a nitration of acetanilide lab, and I'm wondering why the nitroacetanilide crystals are white when the nitroacetanilide crystals are yellow? How does nitrating the compound affect the color?
Also, we were given the option to let our reaction mixture sit in the ice bath from 30 to 45 minutes. Does the amount of time matter, how does it affect the product I obtained?

Thanks a bunch,
Erin

Offline FeLiXe

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Re: Why is nitroacetanilide yellow?
« Reply #1 on: October 11, 2006, 05:04:35 PM »
consider that the nitro group is conjugated to the system

generally conjugation lowers the absorption wavelength. a nitro group lowers the absorption wave length even more than just conjugated carbons because the electron cloud is delocalised.

the absorption wavelength moves from ultraviolet to violet. violet absorption means that your substance is yellow.
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Offline Borek

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Re: Why is nitroacetanilide yellow?
« Reply #2 on: October 12, 2006, 02:25:45 AM »
why the nitroacetanilide crystals are white when the nitroacetanilide crystals are yellow?

 :)
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Offline AWK

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Re: Why is nitroacetanilide yellow?
« Reply #3 on: October 12, 2006, 02:48:03 AM »
Acetanilide is white, nitroacetanilide is yellow.
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