Structure of Nanoparticles Derived from Designer Surfactant TPGS‐750‐M in Water, As Used in Organic Synthesis

Abstract

Using density functional theory and the COSMO-RS implicit solvent model, we predict the structure and physical chemical properties of nanomicelles derived from the designer surfactant TPGS-750-M used in organic synthesis. We predict that the influence of chain length of the PEG region is low, while the termination of the PEG chain (-OH vs.-OCH ) plays a very large role. The interfacial tension is considerably lower between the micellar and water phases for the -OH than the -OCH terminated surfactant, and our calculations reproduce the large difference observed in average particle size as a function of PEG chain termination. We propose a structure for the nanoparticles formed by TPGS-750-M in water that is consistent with a ≈50 nm average diameter, which is significantly larger than a single micelle. According to the calculations, each nanoparticle would consist of 30-40 aggregated TPGS-750-M micelles forming a compartmentalized nanoparticle, with considerable amounts of water in the PEG region. The whole particle is stabilized by vitamin E succinate at the nanoparticle-water interface. In the presence of Zn dust or powder, the surfactant collides with the Zn surface, and by interactions with the hydrophobic inner cores, form organozinc species that are protected from the surrounding water. This explains why highly moisture-sensitive Negishi-like couplings take place in surfactant-water systems.

Synthesis of NH‐Sulfoximines by Using Recyclable Hypervalent Iodine(III) Reagents under Aqueous Micellar Conditions

“…Under the surfactant catalysis, the water‐promoted aggregation of TPGS‐750‐M enables the formation of nanomicelles, which surround the water‐insoluble organic substrates and provide a facile environment for reaction. As water should participate in the reaction, the organizational aspects of the formed micelles, which place water within the PEG region and close to the inner cores also facilitate the essential conversion . During the reactions, the steps that need water may take place outside the micelle's inner core to afford the product, which then re‐enters to undergo the following conversion.…”

“…As water should participate in the reaction, the organizational aspects of the formed micelles, whichp lace water within the PEG region and close to the inner cores also facilitate the essential conversion. [28] During the reactions, the steps that need water may take place outside the micelle's inner core to afford the product, whicht hen re-enterst ou ndergo the following conversion. The ammonium carbonate supplying ammonia could be either inside or out, depending on its distribution to provide the NH 3 .…”

Micelle‐Enabled One‐Pot Guanidine Synthesis in Water Directly from Isothiocyanate using Hypervalent Iodine(III) Reagents under Mild Conditions

“…Among three surfactants, TPGS‐750‐M gave the best result, providing guanidine 5 a in 60 % yield (Table , entry 3–5). The superiority of this surfactant over the other could be explained by highly stable and suitable size of particle formed in water, which could accelerate the reaction . Changing to more hydrophobic hypervalent iodine(III), BTB (Bis( tert ‐butylcarbonyloxy)iodobenzene) resulted in slightly lower yield of 5 a (Table , entry 6).…”

“…The superiority of this surfactant over the other could be explained by highly stable and suitable size of particle formed in water, which could accelerate the reaction. [15] Changing to more hydrophobic hypervalent iodine(III), BTB (Bis(tert-butylcarbonyloxy)iodobenzene) resulted in slightly lower yield of 5a (Table 1, entry 6). We next surveyed the effect of base ( Table 1, Scheme1.Guanidines with biologicalactivities and synthetic approaches.…”

“…[1][2][3] Since then many elegant reactions have been reported. [4][5][6][7][8][9][10][11][12] Although on-water reactions offer much benefits, wide-spread adoption has been limited by inability of on-water reaction to be adapted to all traditional chemical transformation reactions due to heterogeneous behaviour.I nr ecent years, new developments in surfactant technology created by Lipshutz [13][14][15][16][17][18] and others [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] have significantly made an improvement for aqueous reactions allowing reaction to occur "in-water" via the formation of micelles,t hereby providingh igh reproducibility and reactivity.…”