The molecule is zwitterionic form of thiomorpholine-3-carboxylic acid arising from transfer of a proton from the carboxy to the amino group; major species at pH 7.3. It is a conjugate acid of a thiomorpholine-3-carboxylate. It is a tautomer of a thiomorpholine-3-carboxylic acid.
thiomorpholin-4-ium-3-carboxylate