How do zwitterions behave in different solutions and solid states?

[crays]

Hi, I'm wondering how zwitterions works? For example, alanine.

NH₃⁺-CH(CH₃)-COO^-

This is when it is in a neutral form right? But my teacher taught me that, when you add it into a alkali or acid solution. Let's take alkali for instance, the OH^- reacts with the NH₃⁺. But by my knowledge, OH^- would mean a basic solution and NH₃⁺ is a base. How could a base react with a base?

 

[Borek]

No, -NH₃⁺ is an acid. -NH₂ is a base.

Compare Brønsted-Lowry theory of acids and bases.

 

[crays]

Thanks for the reply. I'm clear now. So when alanine is in solid form, will it have the zwitterion form? the NH₃⁺ end and COO^- end? Or does this only occur in water/acid/alkali ?

 

[Borek]

I doubt it will be strictly zwitterion. However, without knowing exact crystallic structure it can be difficult to predict what is going on in the solid. Seems logical that hydrogen bonding between COOH and NH2 plays some role in the crystal structure.