Micelles into Glycerol Solvent: Overcoming Side Reactions of Glycerol

Abstract

The ring-closing metathesis (RCM) of diethyl diallylmalonate in glycerol micellar conditions was studied using microwave irradiation. The micellization of different cationic surfactants in glycerol was first investigated. The results show the superiority of micellar catalysis in glycerol for a RCM reaction compared to glycerol alone, limiting byproduct formation. In comparison with the classical solution syntheses, the method here described allows safer reaction conditions, less hazardous chemical syntheses, and use of renewable feedstocks. The practical workup, separation, and purification operations minimize the use of materials.

Microwave-ultrasound simultaneous irradiation: a hybrid technology applied to ring closing metathesis

“…We previously reported that the RCM of DEDAM 1 led to moderate yields of cyclized product 2 when the reaction was performed in pure glycerol as solvent 35 (leading to the formation of glycerol ester by-products or to substrate polymerization). By performing the reaction in hydrophobic micelle core using the dicationic (gemini) 12-2-12 surfactant (CMC = 9.65 mM in glycerol), 28 the substrate was protected from the formation of glycerol esters. 35 Microwave activation alone was firstly applied: the substrate DEDAM 1 was fully converted only with G-II and HG-I catalysts ( Table 1, entries 2 and 3 respectively), with HG-I leading to a better yield.…”

“…In particular, reaction in the micelle core results in a 'highly concentrated' medium similar to neat conditions, already described to favour oligomerization under ultrasound. 28,74 This is due to the high intensity sonication, delivering a focused energy within a small, concentrated area, contrarily to the indirect sonication method with the plate-probe sonicator for which the ultrasonic intensity delivered inside the vessel was lower. In fact, the ultrasonic waves first needed to cross the liquid inside the cavity and then the wall of the reactor, before reaching the sample.…”

“…This approach benefits at the same time of the effective heating of glycerol under microwave irradiation, the efficient agitation provided by ultrasound and avoids side-reactions involving glycerol, the reactants being confined into the hydrophobic environment inside the micelle nanoreactor, allowing both the better diffusion of organic substrates into the glycerol phase and inhibition of its reactivity. 27,28 This study is divided into two sections. The first part is devoted to the description of a novel prototype of monomodal apparatus, developed in our laboratories, able to provide simultaneous microwave-ultrasound irradiation (SMUI).…”

Effect of Deep Eutectic Solvent Nanostructure on Phospholipid Bilayer Phases

“…This expectation is also supported by the empirical observation that critical micelle concentrations of surfactants in glycerol are often less than half those in ethylene glycol. [71][72][73][74] That DMPC forms a hexagonal phase in ethylene glycol, whilst in water and glycerol it forms a swellable lamellar phase is also indicative of a weaker solvophobic effect. A hexagonal phase reveals the packing parameter 75 of DMPC in ethylene glycol is smaller than in either water or glycerol, consistent with higher hydrocarbon solubility, or at least a greater area of hydrocarbon/solvent contact.…”

Glycerol in subcritical and supercritical solvents

“…Among the recent advances in organic chemistry and specifically in the chemistry of glycerol, alternative technologies such as continuous flow, microwaves, ultrasound, micellar catalysis and critical solvent have been developed. Critical solvents can offer the possibility to develop new chemistry.…”