Kinetics of the oxidation of N-aminopiperidine with chloramine

Abstract

The kinetics of the oxidation of N-aminopiperidine with chloramine was studied at different temperatures, with variable concentrations of the two reactants and at a pH ranging between 12 and 13.5. The reaction showed to be involving two steps: the first corresponded to the formation of a diazene intermediate, the second to the evolution of this intermediate into numerous compounds within a complex reactional chain. The rate law of the first step was determined by the Ostwald method and 2 found to be first order with respect to each reactant. The rate constant was determined at pH = 12.89 and T = 25°C: k 2 = 1.15 × 10 5 exp(-39/RT) M -1 s -1 (E 2 in kJ mol -1 )With decreasing pH value, the first step exhibited acid catalysis phenomena, and diazene was converted into azopiperidine particularly faster. This created overlapping UV-absorptions between chloramine and azopiperidine, also observed in HPLC. GC/MS analyses were used to identify some of the numerous by-products formed. Their proportions are dependent of both pH and the reactants' concentrations ratio. A reaction mechanism taking this relationship into account, was suggested.

Kinetic study of spiramycin removal from aqueous solution using heterogeneous photocatalysis

“…They involve reverse osmosis, adsorption on activated carbons, or advanced oxidation technologies, such as Fenton reaction, ozonation, and peroxidation combined with UV light as well asphotocatalysis [11][12][13][14][15][16][17][18]. The latter proved to be effective in the transformation, deactivation and minimization of persistent compounds in water [19].…”

Kinetic modeling of the synthesis of N-aminopiperidine via the Raschig process: Reaction optimization and continuous process

“…For diluted medium experiments that were carried out to validate the kinetic model, instantaneous concentrations of NH 2 Cl were monitored, by making use of its maximum ultraviolet absorption (e NH2Cl = 458 M À1 cm À1 at k = 243 nm), either by UV spectrophotometry or by HPLC as described in our previous papers [4,5]. Instantaneous concentrations of NAPP formed were also followed by UV after derivation (a method which was developed in our laboratory [7]): NAPP itself is transparent to UV in the studied range (220-350 nm); therefore aliquots were treated with formaldehyde (40-fold excess) in order to convert NAPP formed into its hydrazone (FNAPP) which has a maximum absorption in UV at 237 nm (e FNAPP = 4485 M À1 cm À1 ).…”

“…Many side-reactions were identified and kinetically quantified, the most important of which are the oxidation of NAPP with chloramine [5] and the chlorineatom transfer reaction between chloramine and piperidine [6]. In this paper, we report our results on the elaboration of a kinetic model, which reflects the experimental results of the main and side-reactions occurring during NAPP synthesis.…”

Weak hydrogen and dihydrogen bonds instead of strong N–H⋯O bonds of a tricyclic [1,2,4,5]-tetrazine derivative. Single-crystal X-ray diffraction, theoretical calculations and Hirshfeld surface analysis

“…6,7 To our best knowledge, tricylic aliphatic compounds based on [1,2,4,5]-tetrazine (i, see Scheme below) were first obtained by the reaction of Angeli's salt, Na 2 N 2 O 3 , with heterocyclic amines, morpholine and piperidine in the presence of hydrochloric acid. 6 Quite recently, Darwich et al 8 published the results of the kinetic studies on N-aminomorpholine oxidation with chloramine where dipyridododecahydro-s-tetrazine (i, X = CH 2 ) was one of the reaction products. The compound was also formed along with a hydrido iridium(III) phenoxide complex by the reaction of an aminonitrene complex of Ir(III) with phenol.…”