HALOGENATION AND AMINATION DUAL PROPERTIES OF HALOAMINES IN RASCHIG ENVIRONMENT - A CHLORINE TRANSFER-REACTION BETWEEN CHLORAMINE AND 3-AZABICYCLO[3,3,0]OCTANE

The chlorine transfer reaction between 3-azabicyclo[3,3.0]octane ''AZA '' and chloramine was studied over pH 8-13 in order to follow both the amination and halogenation properties of NH2Cl. The results show the existence of two competitive reactions which lead to the simultaneous formation of N-amino- and N-chloro- 3-azabicyclo[3,3,0]octane by bimol ecular kinetics. The halogenation reaction is reversible and the chlor ine derivative obtained, which is thermolabile and unstable in the pur e state, was identified by electrospray mass spectrometry. These pheno mena were quantified by a reaction between neutral species according t o an apparent S(N)2-type mechanism for the amination process and a ion ic mechanism involving a reaction between chloramine and protonated am ine for the halogenation process. Amination occurs only in strongly ba sic solutions (pH greater than or equal to 13) while chlorination occu rs at lower pH's (pH less than or equal to 8). At intermediate pH's, a mixture of these two compounds is obtained. The relative proportions of the products are a function of intrinsic rate constants, pH and pK( a) of the reactants. The rate constants and thermodynamic activation p arameters are the following: k(1) = 45.5 X 10(-3) M(-1) s(-1); Delta H -1(0#) = 59.8 kJ mol(-1); Delta S-1(0#) = -86.5 J mol(-1) K-1 for amin ation; k(2) = 114 X 10(-3) M(-1) s(-1); Delta H-2(0#) = 63.9 kJ mol(-1 ); and Delta S-2(0#) = -48.3 J mol(-1) K-1 for chlorination. The abili ty of an interaction corresponding to a specific (NH3Cl+/RR'NH) or gen eral (NH2Cl/RR'NH) acid catalysis has been also discussed. (C) 1997 Jo hn Wiley & Sons, Inc.