Catalytic Process for the Hydroxide-Initiated Reaction of the “Weakly Acidic” Substrate in the Third-Liquid Phase-Transfer Catalytic System

Abstract

Generation processes of the third phase and the carbanion for Horner–Wadsworth–Emmons (HWE) reaction of the “weakly acidic” substrate in the third-liquid phase-transfer catalysis (TLPTC) system were investigated. The third phase consisted of Et2PO4 – (diethyl phosphate anion), Br– and TBA+ (tetrabutylammonium), and molar content of Et2PO4 – was 6.65 times greater than that of TBA+. The true catalyst was the complex of TBA+Et2PO4 – and TBAB. Excess Et2PO4 – could be associated with TBA+Et2PO4 –, resulting in generation of the third phase. The “true” catalyst showed a higher catalytic activity and the reaction equilibrium constant for the third-phase cycle was 26 times greater than that for the organic-phase cycle. Results from background reaction, interfacial tension, and hydrogen–deuterium exchange reaction experiments suggested that the phosphonate were deprotonated by “naked” OH–, without help of the catalyst. These novel generation processes of the third phase and the carbanion were key factors for this efficient TLPTC system.

Design and Development of Novel Continuous Flow Stirred Multiphase Reactor: Liquid–Liquid–Liquid Phase Transfer Catalysed Synthesis of Guaiacol Glycidyl Ether

“…At the lower end of the reactor, a drain valve (19) was installed. Three feed vessels (24,25,26) were used to store each phase feed. Three single piston pumps (21,22,23) with pulse dampeners were used to pump each phase at the respective inlets.…”

“…Additionally, there are reactions like esterification of potassium 4-methoxyphenylacetate [16], sodium benzoate [17], synthesis of n-butyl salicylate by esterification of sodium salicylate [18], benzoylation of sodium 4-acetylphenoxide [19], 4-chloro-3-methylphenol sodium salt [20], synthesis of butyl salicylate [21], benzyl salicylate [22], and ultrasound-assisted synthesis of dialkyl peroxides [23]. Recently, the Horner−Wadsworth−Emmons (HWE) reaction was studied using an L-L-L PTC system [24][25][26].…”

"A Minireview of Phase-Transfer Catalysis and Recent Trends"

“…However, phase-transfer catalysis also has the disadvantage that it is hard to separate the product from the organic phase [7][8][9]. To solve this problem, researchers have proposed a three-insoluble in the organic or aqueous phase, a third phase can form, and once the third phase is created, the reaction rate increases dramatically [10][11][12][13][14][15].…”

Ultrasound-Assisted Green Synthesis of Dialkyl Peroxides under Phase-Transfer Catalysis Conditions

“…However, to avoid the additional costs associated with the immobilization of the catalyst on a solid support, we applied a tri-liquid PTC technique to obtain dialkyl peroxides [8,9]. In this technique the liquid PTC catalyst is predominately located in a third liquid phase and can be easily separated from the reaction mixture [10][11][12].…”