# Why does polymerization reaction between amino acids produce different products as compared to the reaction between amine and carboxylic acid? [closed]

Elaborate:

Amino Acid A + Amino Acid B -> Peptide chain + H20

Amine + Carboxylic Acid -> Salt

Why do they have different outcomes when breaking it down they are both the reaction between the 2 function groups: carboxyl(-COOH) and amino (-NH2)

## closed as off-topic by Mithoron, A.K., Tyberius, Jon Custer, aventurinSep 28 '18 at 20:12

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In mild conditions amines + carboxylic acids end up producing salts. So do amino acids. Mind you, there is no need to use two of them, for each amino acid already has $$\ce{-COOH}$$ and $$\ce{-NH2}$$. In a way, each amino acid is a salt in itself.
If you remove water, then amino acids produce compounds with $$\ce{-CONH}-$$ link. So do amines with carboxylic acids. You must have heard of nylon; indeed, it is a polymer, not unlike peptides.
The issue here is that $$\rightarrow$$ means two different things in the reactions you've written.