Investigations of the reactions of monochloramine and dichloramine with selected phenols: Examination of humic acid models and water contaminants

Our paper reports on the reactivities and orientations of two common phenols, phenol (2) and m-cresol (3), and some of their chlorinated intermediates with aqueous monochloramine, NH(2)Cl, and dichloramine, NHCl(2). We also examined the further reactivity of 2,4,6-trichlorophenol (4) with the chloramines. The phenols are an important area of investigation because they are substituents in the humic acids and are common contaminants in water. m-Cresol (3) was found to be more reactive than pheniol (2) with both chlorinating agents. Both NH(2)Cl and NHCl(2) were sufficiently reactive to chlorinate all positions ortho and para to the hydroxyl groups. Mono- and dichloramine showed the same orientation with 2 but different orientations in their reactions with the substituent phenols. Indophenol (as its salt) was formed to a minor extent at high pH but not at pH 9. Both NH(2)Cl and NHCl(2) rapidly replaced the parachlorine in 2,4,6-trichloro phenol (4) to give a mixture of 2,6-dichloro-1,4-benzoquinone-4-(N-chloro) imine (5) and 2,6-dichloro-1,4-benzoquinone (18). Similar reactions occur with 2,4,6-trichloro-m-cresol (17) and 2,4,6-trichloro-3-methoxyphenol (29). The products for 17 were confirmed (13)C NMR, by mass spectrometry (El and Cl), (1)H NMR, and IR; the products for 29 were confirmed by mass spectrometry (El and Cl) and IR. An ion radical mechanism is suggested to account for the chlorine replacement by the chloramines. [No side chain oxidation of the methyl group in 17 in H(2)O or ether occurred, with or without ultraviolet radiation.] Both 5 and 18 underwent further chlorination with NH(2)Cl or NHCl(2). Imine 5 did not function as a chlorinated agent.