To optimize yields, the study of reaction kinetics related to the synthesis of 2-hydroxyethylhydrazine (HEH) obtained from the alkylation of N 2 H 4 by 2-chloroethanol (CletOH) was carried out with and without sodium hydroxide. In both cases, the main reaction of HEH formation was followed by a consecutive, parallel reaction of HEH alkylation (or dialkylation of N 2 H 4 ), leading to the formation of two isomers: 1,1-di(hydroxyethyl)hydrazine and 1,2-di(hydroxyethyl)hydrazine. In this study, hydrazine and hydroxyalkylhydrazine alkylations followed S N 2 reactions triggered directly by CletOH or indirectly in the presence of a strong base by ethylene oxide, an intermediate compound. The kinetics was studied in diluted mediums by quantifying HEH and CletOH by gas chromatography and gas chromatography coupled with mass spectrometry (GC-MS). The activation parameters of each reaction and the influence of a strong base present in the medium on the reaction mechanisms were established. A global mathematical treatment was applied for each alternative. It allowed modeling the reactions as a function of reagent concentrations and temperature. In the case of direct alkylation by CletOH, simulation was established for semi-batch and batch syntheses and was confirmed in experiments for concentrated mediums (1.0 M ≤ [CletOH] 0 ≤ 3.2 M and 15.7 M ≤ [N 2 H 4 ] 0 ≤ 18.8 M). Simulation therefore permits the prediction of the instantaneous concentration of reagents and products, in particular ethylene oxide concentration in the case of indirect alkylation, which must be as weak as possible.

The Raschig synthesis of hydroxyethylhydrazine (HEH) is studied, that is, the reaction of monochloramine on ethanolamine. The formation of HEH is monitored by UV spectrometry, and the influence of temperature and pH is studied. The primary reaction is an SN 2 -type mechanism, whereas the main secondary reaction is the oxidation of HEH by monochloramine. This reaction is also monitored by UV spectrometry, and the oxidation product is identified by GC-MS analysis, showing the formation of hydroxyethylhydrazone. The reaction mechanisms and the rate constants were determined, and the results permit establishing the main reactions occurring during HEH synthesis. These reactions were validated in a concentrated medium, with the systematic study of the influence of the molar ratio p ([HEH] 0 /[NH 2 Cl] 0 ) and the final sodium hydroxide concentration and temperature. A comparison is made with the other synthesis process already published, that is, the alkylation of hydrazine by either chloroethanol or epoxide. C

In this paper, different hydrazines are synthesised by the indirect Raschig process. This consists of introducing a substituted chloramine (R 1 R 2 NCl) into liquid ammonia under pressure to obtain the corresponding hydrazine (R 1 R 2 NNH 2 ). The experimental results, in disagreement with those reported in the literature, lead us to propose a new mechanistic scheme involving a chlorine transfer reaction. Thus, the formation of chloramine (NH 2 Cl) and the amine (R 1 R 2 NH) occurs first. Chloramine reacts immediately with the substituted amine, in agreement with the direct Raschig process, to produce the hydrazine. Under these conditions, the nature of the hydrazine is kinetically controlled by the excess amine. It is then possible to synthesise different hydrazines from the same substituted chloramine. This mechanism is validated by the following syntheses: unsymmetric dimethylhydrazine (UDMH), N-aminopiperidine (NAPP) and N-amino 3-azabicyclo[3.3.0]octane (NAZA).

. Ammoniadimethylchloramine system: kinetic approach in an aqueous medium and comparison with the mechanism involving in liquid ammonia. International Journal of Chemical Kinetics, Wiley, 2008, 40 (6) veronique.pasquet@univ-lyon1.fr}. ABSTRACTAfter an exhaustive study of the system ammonia-dimethylchloramine in liquid ammonia, it was interesting to compare the reactivity of this system in liquid ammonia with the same systeme in an aqueous medium. Dimethylchloramine prepared in a pure state, undergoes dehydrohalogenation in an alkaline medium: the principal products formed are N- A global model which explains the mechanisms both in an anhydrous and in an aqueous medium was elaborated.