Little help understanding Dat Destroyer #31

[Dental_14]

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When I did this question I narrowed done my choices to A & B. And I thought B was the answer because Aniline has an electron donating group. However the explanation describes amines as electron withdrawing groups. I thought the lone pairs on the nitrogen would make it an electron donating group thus making it more basic.

 

[510586]

yea that's odd, because NH2 is one of the very strong electron donating groups on a benzene ring (NO2 is the withdrawing version usually). I got that right without explanation because the others have resonance which stabilizes the conjugate base, making them more acidic while a) has no resonance to stabilize it. (Using the CARDIO thing since the atom and charge are same in everything but the resonance is not)

 

[Dental_14]

I forgot resonance would increase the acidity thanks, that makes sense to why answer choice A would be more basic. But I still don't see why aniline would be considered to have an EWG.
Thanks for the help.

 

[510586]

I forgot resonance would increase the acidity thanks, that makes sense to why answer choice A would be more basic. But I still don't see why aniline would be considered to have an EWG.
Thanks for the help.

I think every now and then (like once every 200 problems) the explanation is not as clear as I would like so I post on the forums to clarify or people who are more knowledgeable than me. It seldom happens, and destroyer is a great resource so it doesn't bother me that much. Maybe orgoman will come and clarify this question, because NH2 is really a great EDG in all the cases I've seen.

 

[DAT Destroyer]

I think every now and then (like once every 200 problems) the explanation is not as clear as I would like so I post on the forums to clarify or people who are more knowledgeable than me. It seldom happens, and destroyer is a great resource so it doesn't bother me that much. Maybe orgoman will come and clarify this question, because NH2 is really a great EDG in all the cases I've seen.

Good evening,
510586

Orgoman is here🙂


I hope I can clear this up.....This is an easy question. AROMATIC AMINES are not very good bases......the electrons are NOT localized, but delocalized by the benzene ring. Thus.... B, and E are easily eliminated. C is an amide,,,,,which has resonance stabilization......thus not a good base at all. It is between A and D. This is a bit more challenging.

A is an amine with electrons in an sp3 orbital.......D has electrons in an sp2 orbital. Both can act as bases,,,,,indeed since these electrons are readily available to capture a proton.

However.....the electrons are more tightly held on an sp2 carbon.....thus IT is not as good as a base.

Therefore.......Choice A .....cyclopentanamine is the strongest base.

NH2 being an electron donating group is a nice way to look at it......but remember.....A benzene ring will TAKE ELECTRON DENSITY away from the amino group...If this happens.....it becomes a less potent base.

Hope this helps.

Dr. Romano...aka know as Orgoman

 

[Dental_14]

Thank you very much for the clarification

 

[510586]

Nice so my

Good evening,
510586

Orgoman is here🙂


I hope I can clear this up.....This is an easy question. AROMATIC AMINES are not very good bases......the electrons are NOT localized, but delocalized by the benzene ring. Thus.... B, and E are easily eliminated. C is an amide,,,,,which has resonance stabilization......thus not a good base at all. It is between A and D. This is a bit more challenging.

A is an amine with electrons in an sp3 orbital.......D has electrons in an sp2 orbital. Both can act as bases,,,,,indeed since these electrons are readily available to capture a proton.

However.....the electrons are more tightly held on an sp2 carbon.....thus IT is not as good as a base.

Therefore.......Choice A .....cyclopentanamine is the strongest base.

NH2 being an electron donating group is a nice way to look at it......but remember.....A benzene ring will TAKE ELECTRON DENSITY away from the amino group...If this happens.....it becomes a less potent base.

Hope this helps.

Dr. Romano...aka know as Orgoman

Nice so my explanation about resonance was correct I think. Sometimes I'm worried that I get a bunch of questions right but for the wrong reasons. Thanks for coming and helping out!

 

[DAT Destroyer]

Thank you very much for the clarification

Keep hammering away!

 

[csulapredental]

i stil

Good evening,
510586

Orgoman is here🙂


I hope I can clear this up.....This is an easy question. AROMATIC AMINES are not very good bases......the electrons are NOT localized, but delocalized by the benzene ring. Thus.... B, and E are easily eliminated. C is an amide,,,,,which has resonance stabilization......thus not a good base at all. It is between A and D. This is a bit more challenging.

A is an amine with electrons in an sp3 orbital.......D has electrons in an sp2 orbital. Both can act as bases,,,,,indeed since these electrons are readily available to capture a proton.

However.....the electrons are more tightly held on an sp2 carbon.....thus IT is not as good as a base.

Therefore.......Choice A .....cyclopentanamine is the strongest base.

NH2 being an electron donating group is a nice way to look at it......but remember.....A benzene ring will TAKE ELECTRON DENSITY away from the amino group...If this happens.....it becomes a less potent base.

Hope this helps.

Dr. Romano...aka know as Orgoman

l still don't get this .. b c and E all have electron donating groups on them.. shouldn't that make them STRONG BASES