Ammonia or Aniline? Basically...

[torobcheh21]

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Which is more basic...ammonia or analine? And is there a general trend to follow?

My kaplan stuff says ammonia is more basic than aniline but people online say otherwise. One site I found says " All of the amines are more basic than ammonia, but primary and secondary amines are the most basic." But this doesn't match up with the answer in kaplan. What's right here?

Thanks

 

[aqz]

Kaplan is right. You can learn this through either the pre-med way, or you can actually understand it.

From the pre-med way (or the let's just memorize every single thing), aniline's conjugate acid has a pka of 4.6, while ammonium has a pka around 9, meaning that aniline's conjugate acid is more willing to give up a proton, which in other words means aniline itself is more likely to not accept a proton and is less basic/more acidic.

To understand this, on the other hand, take a look at what the amine group is attached to...a benzene. The benzylic effect (or just resonance) will stabilize aniline more, making it more stable without the extra proton.

 

[torobcheh21]

right and a more stable base means a less reactive one...aka a weaker base right. great thanks!