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Topic: Sulfanilamide PKa values  (Read 11041 times)

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Offline anilin

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Sulfanilamide PKa values
« on: October 28, 2009, 02:36:31 PM »
Why does sulfanilamide have two different pka values? One in acidic range and the other in basic range?
Is it a basic compound?
Thanks

Offline KritikalMass

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Re: Sulfanilamide PKa values
« Reply #1 on: October 28, 2009, 05:27:37 PM »
Look at its structure. You can see it has two acidic groups, thus it has two different pKa- one of the groups is more acidic (the hydrogen comes off easier) than the other one.

Offline anilin

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Re: Sulfanilamide PKa values
« Reply #2 on: October 28, 2009, 05:44:14 PM »
Look at its structure. You can see it has two acidic groups, thus it has two different pKa- one of the groups is more acidic (the hydrogen comes off easier) than the other one.
do you mean two NH2 groups? is NH2 not a base?

Offline KritikalMass

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Re: Sulfanilamide PKa values
« Reply #3 on: October 28, 2009, 06:27:56 PM »
do you mean two NH2 groups? is NH2 not a base?
Yes, I mean the the two NH2 groups. And NH2 is slightly basic but you titrate these things with a strong base such as NaOH which is much more basic than the NH2, so the OH- is able to rip one of the hydrogens off each of the NH2 groups. As a result, you end up with a sulfanilamide salt and water.

Hope that helps!

Offline Xboss

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Re: Sulfanilamide PKa values
« Reply #4 on: November 05, 2009, 01:15:58 PM »
thanks Kritikalmass .

nice read ... i'm working on that drug's derivatives

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