Piperazine Alkoxylation by 1,2-Epoxypropane and 1,2-Epoxybutane

Piperazine derivatives are widely used as intermediates in the production of various surfactants and pharmaceuticals, and can also be used as amine absorbents activator components for the hydrocarbon gases purification from hydrogen sulfide and carbon dioxide. In the present work, piperazine alkoxylation kinetic regularities with unsymmetrical epoxides - 1,2-epoxypropane and 1,2-epoxybutane - in the presence of water as a catalyst in a concentration 1-50% by weight, in the temperature range from 60 to 130 °C and a molar ratio of reagents (epoxide/piperazine) from 0.4 to 0.8 are presented. It is shown that piperazine alkoxylation with the indicated unsymmetrical epoxides is described by the kinetics of series-parallel reactions, and the temperature regime does not have a significant effect on the ratio of mono- and disubstituted piperazines in the reaction mass. During alkoxylation, along with products of the “normal” structure (secondary alcohols), compounds obtained due to the “anomalous” the epoxide oxirane ring opening (primary alcohols) are also formed. The yield of “anomalous” structure products in terms of “normal” structure amino alcohols does not exceed 2% during alkoxylation of piperazine with 1,2-epoxypropane and 0.5% with 1,2-epoxybutane. N-(2-hydroxyalkyl)-piperazines were isolated from the resulting reaction mass by laboratory rectification, and N,N’-bis(2-hydroxyalkyl)-piperazines were isolated by triple recrystallization from methanol. The composition and structure of the isolated individual compounds were characterized by such physicochemical methods as IR, 1H NMR and 13C spectroscopy. The results obtained in the study may be of interest in the development or optimization of the process for obtaining β-amino alcohols based on piperazine. For citation: Leont’yeva M.E., Demidova Y.V., Demidov P.A., Dronov S.V. Piperazine alkoxylation by 1,2-epoxypropane and 1,2-epoxybutane. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2025. V. 68. N 10. P. 103-108. DOI: 10.6060/ivkkt.20256810.7214.