Comparative Study on Rosmarinic Acid Separation by Reactive Extraction with Amberlite LA-2 and D2EHPA. 1. Interfacial Reaction Mechanism and Influencing Factors

Abstract

The mechanism of reactive extraction of rosmarinic acid with Amberlite LA-2 (secondary amine) and D2EHPA (organophosphoric acid) was analyzed for three solvents with different polarities (n-heptane, n-butyl acetate, dichloromethane), with or without 1-octanol. Thus, in the absence of 1-octanol, the stoichiometric ratio between the rosmarinic acid and Amberlite LA-2 was 1:1 for dichloromethane, 1:2 for butyl acetate, and 1:4 for n-heptane. In the presence of 1-octanol, the formation of aminic adducts is restricted, and the structures of the interfacial complexes reflect the following stoichiometries for the interfacial reaction between the solute and Amberlite LA-2: 1:1 for dichloromethane and butyl acetate and 1:2 for n-heptane. However, regardless of 1-octanol addition to the organic phase, the extraction of rosmarinic acid with D2EHPA occurred only through the formation of an interfacial compound containing one acid molecule and two molecules of extractant for all considered solvents. In the case of reactive extraction with Amberlite LA-2, the highest extraction constant was reached for low-polarity solvents, which promotes the formation of aminic adducts. In contrast, an increase of the organic-phase polarity positively influenced the value of the extraction constant for extraction with D2EHPA.

Comparative Study on Pantothenic Acid Separation by Reactive Extraction with Tri-n-octylamine and Di-(2-ethylhexyl) Phosphoric Acid

“…However, as it was observed for the reactive extraction of other carboxylic acids, 13,15,16 due to the steric hindrance induced by the voluminous molecule of pantothenic acid and its initial concentration which is lower compared to that of TOA, the formation of acidic adducts at the interface is hindered. Therefore, the interfacial compound could be of ammonium salt type as a result of neutralization of the solute carboxylic group with one extractant molecule, or of aminic adducts type, for n ≥ 2.…”

Stoichiometric and Spectroscopic Study of Reactive Extraction of Phenylacetic Acid with Tri-n-Butyl Phosphate

“…42 The slope of the straight line of Eq. (9) was used to determine the numbers of tri-n-butyl phosphate molecule participating in the interfacial reaction with the acid molecule and the extraction equilibrium constant, E is evaluated by intercept of the line.…”

Studies on Reactive Extraction of Itaconic Acid from Fermentation Broths

“…This method is especially useful for separating compounds with similar physical properties or when conventional separation techniques like distillation or crystallization are not effective or economically viable [7]. Reactive extraction is commonly employed for efficiently separating organic acids, leading to improved results [8][9][10][11][12]. Various types of extractants have been evaluated for IA separation [12][13][14][15][16][17][18].…”