Halogenation and amination dual properties of haloamines in Raschig environment: A chlorine transfer reaction between chloramine and 3‐azabicyclo[3,3,0]octane

Abstract

This work comes as a part of the reactivity of chloramine with mono-and disubstituted amines with the ABSTRACT 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 NH 2 Cl. 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 bimolecular kinetics. The halogenation reaction is reversible and the chlorine derivative obtained, which is thermolabile and unstable in the pure state, was identified by electrospray mass spectrometry. These phenomena were quantified by a reaction between neutral species according to an apparent S N 2-type mechanism for the amination process and a ionic mechanism involving a reaction between chloramine and protonated amine for the halogenation process. Amination occurs only in strongly basic solutions (pH Ն 13) while chlorination occurs at lower pH's (pH Յ 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 parameters are the following: k 1 ϭ 45.5 ϫ 10 Ϫ3 M Ϫ1 s Ϫ1 ; ⌬H 1 0# ϭ 59.8 kJ mol Ϫ1 ; ⌬S 1 0# ϭ Ϫ 86.5 J mol Ϫ1 K Ϫ1 for amination; k 2 ϭ 114 ϫ 10 Ϫ3 M Ϫ1 s Ϫ1 ; ⌬H 2 0# ϭ 63.9 kJ mol Ϫ1 ; and ⌬S 2 0# ϭ Ϫ 48.3 J mol Ϫ1 K Ϫ1 for chlorination. The ability of an interaction corresponding to a specific (NH 3 Cl ϩ /RRЈNH) or general (NH 2 Cl/RRЈNH) acid catalysis has been also discussed.

Interaction between substituted chloramines and liquid ammonia using the indirect Raschig process

“…The first step of the mechanism corresponds to an interaction between dimethylchloramine and ammonia by analogy with the chlorine transfer phenomena observed in the aqueous medium. [15][16][17][18] The formation of dimethylamine and chloramine initially occurs according to the following pre-equilibrium (3):…”

Kinetic characterization of a transient reaction by degeneration of the precursor mechanism: Application to the synthesis of 3,4‐diazabicyclo[4.3.0]‐ non‐2‐ene

“…The couple including a protonated form is more reducing due to the positive charge on the nitrogen atom, which leads to an increase in rate compared to the neutral process. The two schemes correspond to a chlorine exchange previously observed for the case of amines, amino acids, and peptides [18,45–55].…”

“…The influence of pH is not surprising. It plays a fundamental role in hydrazine chemistry, which manifests itself either in a rate acceleration or a change in the nature and ratio of the reaction products 4,15,18,33,38,39. The mechanism of formation of 3,4‐diazabicyclo[4.3.0]non‐2‐ene includes two major parts (Scheme ):…”

“…Alicyclic hydrazines were synthesized by Raschig's method as follows 11–14: This more environmentally sound route constitutes a general method for the preparation of unsymmetrical‐substituted hydrazines. However, it has the disadvantage of leading to numerous by‐products 15–20.…”

Kinetics of reduction of chloramines by sodium borohydride

“…The NH 2 Cl-AZA interaction undergoes a change of orientation according to acidification of the medium. 15,16 In slightly alkaline medium, the quantity of 2 decreases in favor of N-chloro-3-azabicyclo [3.3.0]octane (3) (CIAZA), which becomes preponderant at pH 8.…”