Glyceryl monostearate (monoglyceride) is white waxy It is a flake or bead solid, insoluble in water, and can be dispersed in water by strong shaking with hot water. It is a water-in-oil emulsifier. Soluble in hot organic solvents ethanol, benzene, acetone, mineral oil and fixed oil. The freezing point is not lower than 54℃.
The four production methods of monoglycerides are as follows:
1. Direct esterification method:
Stearic acid and glycerin are reacted at a molar ratio of 1: (1.2~1.3) under the action of 0.2% acidic catalyst at 180~250°C for 2~4 hours; the reactants are quickly cooled to 100°C and alkali is added Neutralize the catalyst and wash it with water to obtain a product containing 40% to 60% of monoester.
2. Transesterification method:
Glyceryl stearate and glycerin are mixed in the presence of 0.06% to 0.1% Cu(OH)2. React at 170-240°C for 1-2 hours. During the reaction, nitrogen gas is introduced for protection. The reactant is deodorized under reduced pressure, neutralized with acid, and refined to obtain a product containing 40% to 60% of monoester.
3. Glycidyl saponification method:
Glycidol and stearic acid are catalyzed by tetraethylammonium iodide at 100~130℃ The reaction lasts for 30 to 70 minutes. After the reactants are refined, a product containing 80% to 90% of the monoester can be obtained.
4. Epichlorohydrin phase transfer catalysis method:
Epichlorohydrin and sodium stearate (2:1, molar ratio) in In toluene, under the catalysis of the phase transfer catalyst tetrabutylammonium bromide, react at 90-110°C for 2 hours; the reactants are washed with sodium chloride solution, the organic phase is separated, and toluene and unreacted epichlorohydrin are distilled away The hard Chemicalbook fatty acid glycidyl ester is obtained, which is hydrolyzed with 0.1 mol/L NaOH solution, separated, dried, and recrystallized with n-hexane to obtain a product with a monoester content of more than 90%. Monoester products with a content of 40% to 60% can obtain more than 90% high-concentration products through molecular distillation.
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