Hydrogen-bonded aggregates in the mixtures of piperidine with water: thermodynamic, SANS and theoretical studies

TL;DR

This study investigates the structure and thermodynamics of piperidine-water mixtures, revealing the formation of semiclathrate-like structures at low concentrations and bicontinuous microemulsions at higher concentrations through experimental and theoretical methods.

Contribution

It provides new insights into the microstructure and stability of piperidine-water mixtures using thermodynamic, SANS, and theoretical analyses.

Findings

Semiclathrate-like structures form at low piperidine concentrations.

Bicontinuous microemulsion structures occur at intermediate concentrations.

Piperidine is fully miscible with water due to low complex stabilization energy.

Abstract

Structures resembling semiclathrates probably arise in liquid aqueous solutions of piperidine at the amine mole fraction below 0.03. With the increasing concentration, the structures gradually decay, but the 1:1 complexes of piperidine with water remain linked one to another through the O-H...O bonds between the hydration water molecules. A periodic order of the bicontinuous microemulsion type occurs in the range of the mole fractions from 0.08 to 0.5. In the piperidine-rich mixtures, the 1:1 complexes are dispersed uniformly in the amine. Relatively low stabilization energy of these complexes probably causes that piperidine is totally miscible with water.