The Micelle Catalytic Performance Of Newly Designed Surfactants Based On Guerbet Alcohols

Guerbet alcohol, usually contained2-hexyldecyl alcohol and2-octyllauryl alcohol, is a kind of primary alcohol with beta-branched alkyl chain. Guerbet alcohol has been used in many fields, such as cosmetics, surfactants, lubricating oils and pharmacy, because it has the properties of low viscosity, good biodegradation, low color and thermostability. However, the application of the nonionic surfactant based on Guerbet alcohol in the field of micelle catalysis has not been reported.Most traditional reactions conducted in organic solvents are not consistent with the notion of green chemistry, because80%of chemical waste is estimated to be solvents. To meet the requirement of environment, many researchers have been awarded by American Chemical Society to explore greener solvent. As is well known, water is the most environmentally friendly and inexpensive solvent. However, lots of reactions were prevented by the insolubilities of the reactants. One approach to circumvent this problem is using surfactants that formed micelles in water to provide hydrophobic environment for the reactants. Herein, we have designed and synthesized a new kind of nonionic surfactants (GPGS) used Guerbet alcohol as the hydrophobic chain and applied the surfactants to the synthesis of triazoles and tetrazoles and the oxidation of alcohols.Firstly, a series of nonionic surfactants, composed of a hydrophobic chain (Guerbet alcohol), a polyethylene glycol (PEG) moiety and a succinic acid ester or sebate linker, have been prepared by a simple two-steps process. The cloud point was measured according to the corresponding methods and the HLB value was calculated based on the Davis formula. The size of the micelles formed upon dissolution of in water was investigated by dynamic light scattering (DLS). In addition, the synthesis of some surfactants is scaled up to100g.Secondly, we have studied the micellar catalysis performance of GPGS on the one-pot synthesis of triazoles. Conventional synthesis of triazoles was limited for the use of explosive organic azide. To avoid the problem, we tried to conduct the reaction of alkyl halide with NaN3in micellar solution. It was found that most benzyl halide and aliphatic halide proceeded well to furnished corresponding azides in good yields. Then, we conducted the reaction of alkyl halide, NaN3, alkyne and catalyst in one pot. High yields of triazoles were obtained after24h. The reaction conditions including different surfactants and micelle sizes have been optimized. It was found that the optimal surfactant is5wt%G2oPGS-1500. Under the optimized condition, a series of alkyl halide, halogenated carbonyl compounds and alkynes were used to explore the scope of our protocol. The mechanism of the catalysis has been proposed.Thirdly, we have studied the micellar catalysis performance of GPGS on the synthesis of tetrazoles. Traditional synthesis of tetrazoles usually uses organic solvents or heat, which was not consistent with the green chemistry. To avoid the problem, we have successfully synthesized tetrazoles in water by adding catalytic surfactant. The reaction conditions including different surfactants and micelle sizes have been optimized. It was found that the optimal surfactant is5wt%G20PGS-1500. Under the optimized condition, a series of aryl nitriles were used to explore the scope of our protocol.The last, based on the traditional oxidation of alcohols with2-Iodoxybenzoic acid (IBX) in DMSO does not meet the requirement of environment and the OH-of GPGS can function with IBX to decrease the activity of the oxidant, we have designed a new kind of nonionic surfactants GMPGS and researched the oxidation of primary and secondly alcohols catalyzed by GMPGS in this thesis. The reaction conditions have been optimized, such as different surfactants and micelle sizes. It was found that2wt%GMPGS-2000was the best amphiphile. The mechanism of the catalysis has been proposed.