On the acid behaviour of the alcoholic group of serine

The behaviour of L-serine in strongly alkaline solution was studied at 25 d egrees C and in 3.00 mol/l NaClO4, as a constant ionic medium, to obtain qu antitative information about the eventual dissociation of its alcoholic gro up. A spectrophotometric method was employed to measure the free concentrat ion of hydrogen ions. Two indicators, methyl thymol blue and eriochrome blu e type R, were used. Their values as protonation constants and absorbance c oefficients were determined in advance. The method here proposed has been v alidated beforehand by applying it to D-mannite and glycerine and by compar ing results so obtained with those previously provided by literature. The i nvestigation showed weak acid properties of the -OH of serine and its disso ciation constant was determined. Polynuclear species or further dissociatio n were not observed. (C) 1999 Elsevier Science B.V. All rights reserved.