Chloramines .6. Chlorination of glycylphenylalanine in model solutions and in a wastewater

Model solutions of the dipeptide glycylphenylalanine were chlorinated at pH 7.0 to five different chlorine-to-peptide (Cl-2/peptide) mole ratios and analyzed after 30 min by high-performance liquid chromatography. At Cl-2/peptide mole ratios less than or equal to 1, N-chloroglycylphenylalanine (I) appears to be the only product. At mole ratios greater than or equal to 2, N,N-dichloroglycylphenylalanine (II) was the only product. II decomposes in model solutions (t(1/2) = 6.4 h) at pH 7.0 to form a compound tentatively identified as N-[2-(N'-chloroimino)ethanoyl]phenylalanine (III), an N-chloroaldimine. III, in turn, decomposes (t(1/2) = 36 h) to IV. From C-13- and H-1-NMR, GC/MS, and IR, IV was identified as N-cyanoacylphenylalanine. Glycyl-p-[H-3]-phenylalanine (VI) was synthesized in order to monitor the reaction at low concentrations of the compound in a wastewater. A secondary wastewater (TKN = 1.29 mg of N/L; [NH3]= 0.074 mg of N/L) was inoculated with VI and chlorinated to nine different chlorine concentrations. The stabilities of the tritiated analogs of II and III in the wastewater were comparable to those determined in model solutions.