[omegasynthesis999]

Is there any particular reason why every other acid/base rxn (in my experience) is talked about in terms of conjugate base stability but amine rxns are talked about in terms of conjugate acid stability? Why not keep things consistent and talk about all acid/base rxns in terms of conjugate base stability?

Thanks

[macman104]

Because amines are not typically deprotonated or act in a manner where they gain a negative charge?  It doesn't make a lot of sense to talk about them in those terms because rarely do they react to form a conjugate base, because they ARE the basic item.  Are there other basic compounds that act in a manner similar to amines that we talk about in terms of conjugate basicity?

[omegasynthesis999]

Your right about the last point. However I was wondering why you couldn't just flip the following acid base reactions around: NH3+H2O--> OH- +NH4+ and NH2CH3+H2O-->OH- + NH3CH3+ to make them NH4+ +OH-   --> NH3 + H2O and NH3CH3+  +OH- --> NH2CH3+H2O. For the reversed reactions, the starting bases are the same (OH-), so in terms of reactivity, one could talk about the different acids and the stability of the conjugate base. In other words, why is the NH3 a more stable conjuate base than NH3CH3 or vice versa?

[macman104]

However I was wondering why you couldn't just flip the following acid base reactions around: NH3+H2O--> OH- +NH4+ and NH2CH3+H2O-->OH- + NH3CH3+ to make them NH4+ +OH-   --> NH3 + H2O and NH3CH3+  +OH- --> NH2CH3+H2O. For the reversed reactions, the starting bases are the same (OH-), so in terms of reactivity, one could talk about the different acids and the stability of the conjugate base. In other words, why is the NH3 a more stable conjuate base than NH3CH3 or vice versa?

Oh, you can.  They are reversible reactions, so there is no problem writing those reactions like that.  In this case, the alkylated product is more basic because the alkyl group donates electron density into the nitrogen.

[omegasynthesis999]

So since the alkylated product is more basic than the NH3, that means the equilibrium for the alkylated product lies more in the direction of its acid than the equilibrium of NH3 lies in the direction of its acid. Electron donating groups don't stabilize bases, they make bases stronger. Therefore, NH3 is the more stable conjugate base. Am I right?