Acidity/Basicity as a result of substituents

[Hemichordate]

In my prep book, it says that if you have a substituent that is electron-donating, it will make the compound less acidic/more basic due to decreased stability and if you have a substituent that is electron-withdrawing (ie halogens), then the compound will be more acidic due to increased stability.

My question is:

Does this apply to every compound, or only to the anions of acids (namely, their conjugate bases)?

For example, if we have a primary amine, and we add an ethyl group to it (ethyl is electron donating), will the amine become more basic? If we add a halogen to it, would it likewise become more acidic?

Thanks

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[Hemichordate]

bump

 

[PiBond]

In my prep book, it says that if you have a substituent that is electron-donating, it will make the compound less acidic/more basic due to decreased stability and if you have a substituent that is electron-withdrawing (ie halogens), then the compound will be more acidic due to increased stability.

My question is:

Does this apply to every compound, or only to the anions of acids (namely, their conjugate bases)?

For example, if we have a primary amine, and we add an ethyl group to it (ethyl is electron donating), will the amine become more basic? If we add a halogen to it, would it likewise become more acidic?

Thanks

i'm hesitant to say "every" compound, but all the ones i can think of follow this trend.

adding an electronegative group stabilizes an anion by delocalizing negative charge. your amine example with the halogen won't apply because even with an electronegative substituent on the nitrogen the compound still doesn't have an acidic hydrogen...NH3 isn't acidic

electron donating groups increase basicity by localizing charge on an atom so that it can abstract a hydrogen...or at least that's how i think of it. addition of an ethyl group will make your amine more basic because it's contributing to the localization of charge on the nitrogen. thus NR3 is more basic than NH3, with R = alkyl group

 

[Hemichordate]

i'm hesitant to say "every" compound, but all the ones i can think of follow this trend.

adding an electronegative group stabilizes an anion by delocalizing negative charge. your amine example with the halogen won't apply because even with an electronegative substituent on the nitrogen the compound still doesn't have an acidic hydrogen...NH3 isn't acidic

electron donating groups increase basicity by localizing charge on an atom so that it can abstract a hydrogen...or at least that's how i think of it. addition of an ethyl group will make your amine more basic because it's contributing to the localization of charge on the nitrogen. thus NR3 is more basic than NH3, with R = alkyl group

So for amines, only electron donating groups have the "regular" effect (and not electron withdrawing groups)?

 

[loveoforganic]

Honestly, you can consider the amine acidic and look at the trends. It still has a hydrogen, so technically, it can still serve as an acid. Electron donating groups would increase basicity of the lone pair, decrease acidity of the protons, and vice versa.