CN101891761B - Method for catalytically synthesizing triethyl phosphate by phase transfer - Google Patents

Abstract

The invention relates to a method for synthesizing triethyl phosphate by phase transfer catalysis. Diethyl phosphate sodium salt is used as raw material, phase transfer catalyst is added, and ethylating reagent is added to the organic solvent and water system to form triethyl phosphate, which is separated and purified to obtain the finished product. Compared with the prior art, the present invention has lower catalyst cost, adopts organic solvent and water as the mixed solvent, and the organic solvent can be recycled, which is environmentally friendly and reduces the synthesis cost. Reusing wastes into organic phosphorus resources with practical value reduces environmental pollution and provides a new way for the industrial production of triethyl phosphate. The method not only has the advantages of fewer reaction steps, simple operation, high yield, high product purity and easy industrial production, but also reduces the environmental pollution of the by-product diethyl phosphate sodium salt in the production process of the fluorescent whitening agent.

Description

Phase transfer catalyzed method for synthesizing triethyl phosphate

technical field

The invention relates to a method for organic synthesis, in particular to a method for preparing triethyl phosphate by phase-transfer catalytic synthesis.

Background technique

The molecular formula of triethyl phosphate is (CH ₃ CH ₂ O) ₃ PO, the English name is Triethyl Phosphate, TEP for short. Molecular weight 182.16, is a colorless transparent liquid, melting point -56.5 ° C, boiling point 215 ~ 216 ° C, relative density 1.064 (20/4 ° C), completely soluble in water, easily soluble in organic solvents such as ethanol, ether, benzene, etc., but As the temperature rises, it will gradually hydrolyze in water. As a high boiling point solvent, triethyl phosphate is widely used. In rubber and plastics, it can be used as plasticizer, catalyst, solvent, stabilizer, curing agent and softener, etc.; it is one of the main raw materials for the preparation of pesticides; it can also be used as plant growth regulator, defoamer, cellulose acetate The production of dyeing auxiliaries, fluorescent glass coatings, etc. The synthesis of the preparation triethyl phosphate reported at home and abroad mainly contains two routes at present. One is that US6673955 reports that phosphorus oxychloride is used as a phosphorylation reagent and then reacted with ethanol to obtain a compound. This synthesis method is due to the generation of hydrogen chloride by-products, which cause product decomposition during the reaction process, resulting in reduced yield and purity. US2636048 discharges the hydrogen chloride generated by feeding nitrogen, which causes a large amount of ethanol loss and reduces the yield. The current production of triethyl phosphate generally has problems such as low yield (50% to 60%) (such as: "New Technology for Triethyl Phosphate Synthesis" on pages 63 to 65 of the fifth issue of "Journal of Hubei University of Technology" volume 22 Research"). Another route, US3136805 report, takes triethyl phosphite as starting material, obtains triethyl phosphate with hydrogen peroxide oxidation under alkaline conditions. The deficiency of this synthetic method is: triethyl phosphite can be hydrolyzed and then causes the yield of triethyl phosphate to reduce. Therefore, the pH value must be strictly controlled to reduce the occurrence of side reactions. The by-product sodium diethyl phosphate in the existing fluorescent whitening agent production process has problems such as polluting the environment and being difficult to handle to varying degrees.

Contents of the invention

The purpose of the present invention is just to provide a kind of method for the synthesis of triethyl phosphate by phase transfer catalysis for the above-mentioned deficiencies in the prior art.

The purpose of the present invention is achieved through the following technical solutions:

The preparation method of phase-transfer catalyzed synthesis of triethyl phosphate comprises the following sequence and steps: the amount of each raw material added is in mol

a. Put the by-product diethyl phosphate sodium salt and phase transfer catalyst in the production process of fluorescent whitening agent into the reactor equipped with reflux condenser, feeding funnel, stirring device and thermometer according to 1:0.01～0.15mol , then add 400ml to 800ml of organic solvent and 0 to 200ml of water per mole of diethyl phosphate sodium salt;

b, heat and stir to dissolve diethyl phosphate sodium salt and catalyst, and heat up to reflux;

C, add diethyl sulfate, the molar ratio of diethyl phosphate sodium salt and diethyl sulfate is 1: 0.5～3mol;

d. Keep the reflux reaction temperature at 70-100°C for a reaction time of 4-10 hours, cool down, and filter with suction to obtain a yellow solution;

e. Wash with saturated sodium bicarbonate to neutrality, then wash twice with water, wash once with saturated sodium chloride, and finally dry with anhydrous magnesium sulfate;

f, rotary evaporation of solvent to obtain triethyl phosphate crude product, yellow transparent liquid;

g. Distill under reduced pressure to obtain pure triethyl phosphate, a colorless transparent liquid.

The purpose of the present invention is achieved through the following technical solutions:

Organic solvents include toluene, xylene, chlorobenzene, acetonitrile or methyl isobutyl ketone. The phase transfer catalyst is benzyltriethylammonium chloride, cetyltrimethylammonium bromide or tetrabutylammonium bromide.

Beneficial effects: compared with the prior art, the cost of the catalyst used in the present invention is lower, organic solvent and water are used as the mixed solvent, and the organic solvent can be recycled, which is friendly to the environment and reduces the synthesis cost, not only for sodium diethyl phosphate The salt is reused, the waste is converted into organic phosphorus resources with practical value, the environmental pollution is reduced, and a new way is provided for the industrial production of triethyl phosphate. The method not only has the advantages of fewer reaction steps, simple operation, high yield, high product purity and easy industrial production, but also reduces the environmental pollution of the by-product diethyl phosphate sodium salt in the production process of the fluorescent whitening agent.

Detailed ways

Below in conjunction with embodiment do further detailed description:

The method for the synthesis of triethyl phosphate by phase transfer catalysis of the present invention takes diethyl phosphate sodium salt as a raw material, adds a phase transfer catalyst, and adds an ethylating reagent (taking diethyl sulfate as an example) in an organic solvent and water system, The generated triethyl phosphate is separated and purified to obtain the finished product. This esterification method is nucleophilic substitution, the organic phase is diethyl sulfate, the solid phase is diethyl phosphate sodium salt, diethyl phosphate sodium salt generates diethyl phosphate anion in the corresponding phase, and then it acts as a The nucleophile is carried by the phase transfer catalyst into the organic phase for nucleophilic substitution reaction with diethyl sulfate.

The reaction formula is as follows:

Phase transfer catalysts are quaternary ammonium salts with the following structure:

In the formula, R ₁ , R ₂ , R ₃ , and R ₄ are respectively C _n H _2n+1 (n=1-16) aliphatic hydrocarbon groups or aryl groups. Wherein the hydrocarbon groups may be the same or different. Quaternary ammonium salts for specific applications, such as benzyltriethylammonium chloride, cetyltrimethylammonium bromide, tetrabutylammonium bromide, etc.; organic solvents for specific applications include toluene, xylene, chlorobenzene, Acetonitrile, methyl isobutyl ketone, etc. Wherein the best phase transfer catalyst is tetrabutylammonium bromide, and the best solvent is toluene, and tetrabutylammonium bromide has the highest reactivity in toluene.

The present invention mixes diethyl phosphate sodium salt, a phase transfer catalyst, toluene and water, slowly heats up to the reflux temperature, adds diethyl sulfate, and reacts at constant temperature for 6 hours. After the reaction, cool, filter with suction, wash with saturated sodium bicarbonate solution until neutral, wash with water, wash with saturated sodium chloride, separate the organic layer, dry with anhydrous magnesium sulfate, and rotate the solvent to obtain the crude product of triethyl phosphate .

Said every 1mol (together 176.0g) of diethyl phosphate sodium salt and 1mol (together to 154.18g) of diethyl sulfate is water: water is 0～200ml, and organic solvent is 400～800ml. The phase transfer catalyst is a quaternary ammonium salt, and the molar ratio of the added raw material diethyl phosphate sodium salt to the phase transfer catalyst is 1:0.01-0.15.

Example 1:

Get 176.0g of diethyl phosphate sodium salt, 12.89g of tetrabutylammonium bromide, 400ml of mixed solvent toluene and 30ml of water and join in the reactor equipped with reflux condenser, feeding funnel, stirring device and thermometer, heat and stir to make phosphoric acid Dissolve diethyl ester sodium salt and tetrabutylammonium bromide, raise the temperature to reflux, add 154.18g diethyl sulfate, keep the reflux reaction for 6h, cool, and filter with suction to obtain a yellow solution, then wash with saturated sodium bicarbonate until neutral , washed twice with water and once with saturated sodium chloride, dried over anhydrous magnesium sulfate, and finally the solvent was rotary evaporated to obtain crude triethyl phosphate, a yellow transparent liquid with a yield of 63.61% to 91.30% and a content of 95%. Distill under reduced pressure to obtain pure triethyl phosphate, a colorless transparent liquid with a refractive index n=1.4055 and a content of 99%.

Example 2:

Get 176.0g of diethyl phosphate sodium salt, 14.58g of cetyltrimethylammonium bromide, 500ml of mixed solvent xylene and 80ml of water, and add them to the reactor equipped with reflux condenser, feeding funnel, stirring device and thermometer , heat and stir to dissolve diethyl phosphate sodium salt and catalyst, raise the temperature to reflux, add 154.18 g of diethyl sulfate, keep reflux reaction for 4 hours, cool, filter with suction to obtain a yellow solution, and then wash with saturated sodium bicarbonate to medium Then wash twice with water and once with saturated sodium chloride, dry over anhydrous magnesium sulfate, and finally spin the solvent to obtain crude triethyl phosphate, a yellow transparent liquid, with a yield of 62.70% to 91.65% and a content of 95%. Distill under reduced pressure to obtain pure triethyl phosphate, a colorless transparent liquid with a refractive index n=1.4055 and a content of 99%.

Example 3:

Get diethyl phosphate sodium salt 176.0g, benzyltriethylammonium chloride 9.09g, mixed solvent chlorobenzene 600ml and water 100ml, join in the reactor that reflux condenser, addition funnel, stirring device and thermometer are housed, Heat and stir to dissolve diethyl phosphate sodium salt and catalyst, raise the temperature to reflux, add 77.09 g of diethyl sulfate, keep reflux reaction for 7 hours, cool, filter with suction to obtain a yellow solution, then wash with saturated sodium bicarbonate until neutral, Wash twice with water and once with saturated sodium chloride, dry over anhydrous magnesium sulfate, and finally spin evaporate the solvent to obtain crude triethyl phosphate, a yellow transparent liquid, with a yield ranging from 53.69% to 91.30% and a content of 95%. Distill under reduced pressure to obtain pure triethyl phosphate, a colorless transparent liquid with a refractive index n=1.4055 and a content of 99%.

Example 4:

Take 176.0g of diethyl phosphate sodium salt, 12.89g of tetrabutylammonium bromide, 800ml of mixed solvent methyl isobutyl ketone and 120ml of water, and add them to the reactor equipped with reflux condenser, feeding funnel, stirring device and thermometer , heat and stir to dissolve diethyl phosphate sodium salt and catalyst, raise the temperature to reflux, add 154.18g diethyl sulfate, keep reflux reaction for 5h, cool, filter with suction to obtain a yellow solution, and then wash with saturated sodium bicarbonate to medium It was washed twice with water and then once with saturated sodium chloride, dried over anhydrous magnesium sulfate, and finally the solvent was rotary evaporated to obtain crude triethyl phosphate, a yellow transparent liquid, with a yield of up to 95.98% and a content of 95%. Distill under reduced pressure to obtain pure triethyl phosphate, a colorless transparent liquid with a refractive index n=1.4055 and a content of 99%.

Claims (2)

1. A method for phase-transfer catalyzed synthesis of triethyl phosphate, characterized in that, comprises the following sequence and steps: each raw material addition is in mol a, the by-product diethyl phosphate sodium salt in the production process of fluorescent whitening agent and benzyltriethylammonium chloride, hexadecyltrimethylammonium bromide or tetrabutylammonium bromide phase transfer catalyst 1mol: 0.01～0.15mol is put into a reactor equipped with a reflux condenser, an addition funnel, a stirring device and a thermometer, and then 400ml～800ml of organic solvent and 0～200ml of water are added per mole of diethyl phosphate sodium salt; b, heat and stir to dissolve diethyl phosphate sodium salt and catalyst, and heat up to reflux; C, add diethyl sulfate, the molar ratio of diethyl phosphate sodium salt and diethyl sulfate is 1: 0.5～3; d. Keep the reflux reaction temperature at 70-100°C for a reaction time of 4-10 hours, cool down, and filter with suction to obtain a yellow solution; e. Wash with saturated sodium bicarbonate to neutrality, then wash twice with water, wash once with saturated sodium chloride, and finally dry with anhydrous magnesium sulfate; f, rotary evaporation of solvent to obtain triethyl phosphate crude product, yellow transparent liquid; g. Distill under reduced pressure to obtain pure triethyl phosphate, a colorless transparent liquid. 2. according to the method for said phase-transfer catalytic synthesis triethyl phosphate of claim 1, it is characterized in that, described organic solvent is selected from toluene, dimethylbenzene, chlorobenzene, acetonitrile or methyl isobutyl ketone.