Use of N-chloro-N-methyl-p-toluenesulfonamide in N-chlorination reactions

摘要

Second-order rate constants (k_2) were determined for the addition of ten nitrogenous organic compounds (benzylamine, 2,2,2-trifluoethylamine chlorhidrate, methylamine chlorhidrate, glycine ethyl ester chlorhidrate, glycine, glycylglycine chlorhidrate, morpholine, pyperidine, pyperazine and dimethylamine) to the N-chloro-Nmethyl- p-toluenesulfonamide (NCNMPT) in the formation reaction of N-chloramines in aqueous solution at 25 °C and ionic strength 0.5 M. The series of nucleophiles considered is structurally very varied and covers five pK_a units. The kinetic behaviour is similar for all compounds, being the eementary step the transfer of chlorine from the NCNMPT molecule to the nitrogen of the free amino group. These reactions were found first order in both reagents. The values of the rate constants indicate that the more basic amines produce N-chloramines more readily. Rate constants for the nucleophilic attack are shown to correlate with literature data for some of these nitrogenous organic compounds in their reaction with N-methyl-N-nitroso-p-toluenesulfonamide. Both reactions involve that the rate determining step is the attack of nitrogenous compounds upon electrophilic centre (Cl or else NO group). NCNMPT is a particularly interesting substrate, for which has not hitherto been published kinetic information, that allows us to assess the efficiency and the competitiveness of this reaction and compare it with other agents with a Cl~+ atom.