Reactions of resorcinol and its chlorinated derivatives with monochloramine: Identification of intermediates and products

An investigation of the reaction of resorcinol (compound 1) and its chlorinated derivatives 4‐chlororesorcinol (compound 4), 4,6‐dichlororesorcinol (compound 5), and 2,4,6‐trichlororesorcinol (compound 2) with monochloramine (NH 2 Cl) in ether and aqueous solution (pH 7) is reported. NH 2 Cl reacted with compounds 1, 2, 4, and 5 to give the pentachloro intermediate, 2,2,4,4,6‐pentachloro‐5‐cyclohexen‐1,3‐dione (compound 3), which underwent ring opening with H 2 O and loss of CO 2 in the presence of NH 2 Cl to produce the following: 1,1,3,5,5‐pentachloro‐3‐penten‐2‐one (compound 6), 1,1,1,3,5,5‐hexachloro‐3‐penten‐2‐one (compound 7), and 1,1,3,5,5,5‐hexachloro‐3‐penten‐2‐one (compound 8). Compound 6 reacted further with NH 2 Cl to give compounds 7 and 8; in the presence of NH 2 Cl, compound 7 rearranged to compound 8. Mechanisms for the preceding reactions are analyzed in detail. Another aspect of the investigation involved a determination of the amounts of chloroform, CHCl 3 , which is produced from compound 3 with NH 2 Cl (4%) and with NaOCl (50%). The low production of CHCl 3 from compound 3 and NH 2 Cl is discussed in connection with the probable reactions of compounds 7 and 8 with NH 2 Cl and H 2 O.