Remarkable improvement of epoxide ring-opening reaction efficiency and selectivity with water as a green regulator

Abstract

Glycidyl esters are synthesized through the epoxide ring-opening reactions, and the reaction efficiency must be greatly improved for green and efficient production. In this work, the structure of the side...

Highly efficient two‐stage ring‐opening of epichlorohydrin with carboxylic acid in a microreaction system

“…Deionized water as another stream, it plays an important role to improve the selectivity, the mechanism and experimental evidence have been presented in detail in our previous research. 10 In Section 3.3 of this work, the effect of water on selectivity was also briefly discussed. The three streams, NDA (with TMAN dissolved), ECH, and water, were delivered by three syringe pumps (Chemyx Fusion 6000).…”

“…This side reaction pathway is more sensitive to temperature than the acid-base reaction, so the formation of EPDA is more obvious at higher temperature. 10 As the downstream targeted product, the formation of EPDA does not affect the selectivity. However, as shown Figure 2C, EPDA can further react with NDA via the same catalytic route as the main reaction of ECH with NDA, leading to the formation of diester.…”

“…However, as shown Figure 2C, EPDA can further react with NDA via the same catalytic route as the main reaction of ECH with NDA, leading to the formation of diester. 10 The formation of one molecule of diester consumes two molecules of NDA, thus causing a significant decline for yield. In addition, the energy consumption for the separation of diester by rectification is extremely high because the boiling point of diester is higher than the…”

“…9 The ring-opening of ECH with carboxylic acids is a kind of strong exothermic reactions, and high reaction temperature can cause severe decline of selectivity. 10 Most of the reported processes were carried out in stirred reactors, as such they always suffered from the disadvantages of poor mixing and insufficient heat transfer. Hence, some compromise measures must be taken to prevent the temperature runaway caused by the release of reaction heat, mainly including reducing the initial temperature and intermittent adding of reactants.…”

“…Once a large amount of heavy side product is formed, all EPDA must be evaporated from the top of rectification column to meet the purity requirement, which causes extensive energy consumption. Low reaction temperature (70 C-90 C) and the intermittent feeding way are usually employed to control the side reactions, but the required reaction time is prolonged to 6-10 h. 11 It has been demonstrated in our previous study 10 that the addition of water can improve the selectivity by prompting the rapid conversion of the reaction intermediate to the targeted product. The reaction time was greatly shortened because the temperature of 100 C was used and all the reactants and catalysts were mixed at one time.…”