Question

explain the acid - base behaviour of amino acids

Answer 1

amino acids as you change the pH by adding either acids or alkalis to their solutions.

For simplicity, the page only looks at amino acids which contain a single -NH2 group and a single -COOH group.

Amino acids as zwitterions

Zwitterions in simple amino acid solutions

An amino acid has both a basic amine group and an acidic carboxylic acid group.



There is an internal transfer of a hydrogen ion from the -COOH group to the -NH2 group to leave an ion with both a negative charge and a positive charge.

This is called a zwitterion.



This is the form that amino acids exist in even in the solid state. If you dissolve the amino acid in water, a simple solution also contains this ion.

A zwitterion is a compound with no overall electrical charge, but which contains separate parts which are positively and negatively charged.

Answer 2

Answer:

Amino acids are the organic compounds having an amino group(-NH₂) and carboxylic group(-COOH) as the functional groups with an alkyl group (-R).

Acid-base behavior of amino acids

An amino acid can behave as a basic amine and an acidic carboxylic group.

                               

                                 NH₂ ⇒basic amine group

                                  |

                              R-CH-COOH ⇒acidic carboxylic group

• In an aqueous solution, the carboxyl group of an amino acid can lose a proton and the amino group can accept a proton to give a dipolar ion called as zwitter ion as,

       

                      : NH₂    O                         + NH₂  O

                         |         ||                             |        ||

                 R  -  CH  -  C - O - H  ⇄    R  -  CH  -  C - O⁻      

                                                              (Zwitter ion)

           

Thus, in this zwitter ionic form, the amino acid acts as acid as well as the base.