1) H2N―CH(R)―COOH + HCl ―> Cl[H3N―CH(R)―COOH]

2) H2N―CH(R)―COOH + NaOH ―> H2N―CH(R)―COONa + H2O

3) H2N―CH(R)―COOH + C2H5OH H2N―CH(R)―COOC2H5 + H2O

4) H2N―CH(R)―COOH <―> +H3N―CH(R)―COO-