New process of preparation of pyrazolidine: synthesis, extraction and flow-sheet

A El Hajj,A.J Delalu,A.J Bougrine,N David,J.-N Jaubert,R Privat

doi:10.1051/matecconf/20130301045

Abstract

A new process for the preparation of the pyrazolidine (PYRZ), by intramolecular Raschig way has been developed in our laboratory [1, 2]. This work is divided into two parts: synthesis and extraction. For the synthesis part: the reaction mechanism of the formation of pyrazolidine is carried out in two successive steps: the first involves the oxidation of 1,3diaminopropane (I, DAP, C3H10N2 ) by sodium hypochlorite (II, OCl ) and formation of N,chloro-1,3diaminopropane (III, C3H9N2Cl). The second consists of a cyclization of N,chloro-1,3-diaminopropane (III) leading to pyrazolidine (IV).

Highlights

A new process for the preparation of the pyrazolidine (PYRZ), by intramolecular Raschig way has been developed in our laboratory [1, 2]
This work is divided into two parts: synthesis and extraction
For the synthesis part: the reaction mechanism of the formation of pyrazolidine is carried out in two successive steps: the first involves the oxidation of 1,3diaminopropane (I, DAP, C3H10N2 ) by sodium hypochlorite (II, OCl-) and formation of N,chloro-1,3diaminopropane (III, C3H9N2Cl)

Summary

Introduction

A new process for the preparation of the pyrazolidine (PYRZ), by intramolecular Raschig way has been developed in our laboratory [1, 2]. The second consists of a cyclization of N,chloro-1,3-diaminopropane (III) leading to pyrazolidine (IV). This synthesis requires an excess of the diaminopropane (DAP) reagent, in comparison to sodium hypochlorite ([DAP] / [OCl-] = 8), in order to increase the yield in pyrazolidine to 80%. Diaminopropane) separation and the recycling of the excess amine upstream of the synthesis This is difficult because of the very close physicochemical properties of these two compounds. - The first stage is a liquid-liquid phase separation, generated by the addition of solid sodium hydroxide. The optimization of these extraction conditions requires knowledge of phase equilibria in the quaternary system H2O-DAP-PYRZ-NaOH. A final purification by selective crystallization is necessary in order to obtain high purity PYRZ

Apparatus

Isoplethic thermal analysis

Determination of the isobaric solid-liquid ternary system H2O-DAP-NaOH

Conclusion