Method for preparing ethyl alkyl ethyl phosphinate through catalysis

Abstract

The invention provides a method for preparing ethyl alkyl ethyl phosphinate through catalysis, which comprises the following steps of: after replacing air in a reaction kettle with inert gas, adding dialkyl alkyl phosphinate, halothane and a supported ruthenium chloride catalyst; and stirring and reacting at a certain temperature for a certain time to prepare alkyl ethyl phosphinic acid ethyl ester, and filtering to obtain the product. Compared with catalysts iodoethane and chloroethane, the chloroethane has the characteristics of low cost, easiness in obtaining and low toxicity, the reaction out-of-control risk is low due to low catalytic activity, and the reaction temperature can be reduced by combining the catalyst with the supported ruthenium chloride.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic synthesis, and particularly relates to a method for preparing ethyl alkyl ethyl hypophosphite. BACKGROUND

[0002] Alkyl ethyl hypophosphite is an important intermediate for synthesizing organic hypophosphite metal salt, which is a new emerging flame retardant with low smoke and non-toxic characteristics. In the prior art, there are mainly three methods to prepare such substances. In 2020, Lier Chemical reported in patent CN109293694B that dichloromethyl phosphine was used as the initial raw material, reacted with water to obtain methyl hypophosphite aqueous solution, and then synthesized aluminum methyl hypophosphite by controlling pH and reacting with aluminum sulfate. In 2021, Suzhou University disclosed a technology in patent CN110229188B, in which a heteroaromatic acetic acid or its derivative was used as the starting material, and a heteroaromatic methyl phosphine acylate was prepared by reacting with persulfate and silver salt as catalyst. In 2023, Lier Chemical again reported a technology in CN111393473B, in which iodine ethane was used as a catalyst, and methyl ethyl hypophosphite was prepared by adding methyl phosphite diethyl ester dropwise into the catalyst solution system.

[0003] In the above technologies, the following deficiencies exist: in the preparation process using dichloromethyl phosphine as the raw material, the reaction is exothermic, a large amount of hydrogen chloride is released, and the reaction is prone to run out of control in large-scale production if not properly controlled, and the hydrochloric acid and methyl hypophosphite are mutually soluble in water, which affects the quality of the subsequent product. In the technology using phosphine reagent and heteroaromatic acetic acid as the substrate, the method is novel, but the silver reagent is difficult to recover, and the purification is carried out by column chromatography, which cannot be scaled up. In the synthesis method using iodine ethane as the catalyst, iodine ethane has the characteristics of high cost, high toxicity, easy decomposition under light and high reactivity, which makes it difficult to control and interrupt the production, and the reaction temperature is high. SUMMARY

[0004] The present application aims to develop a technology using diethyl alkyl phosphite as the raw material to prepare ethyl alkyl ethyl hypophosphite under the condition of halogen ethane and ruthenium chloride supported catalyst, which has the characteristics of stable and controllable reaction, no solvent, low catalyst dosage, easy separation and low toxicity.

[0005] To achieve the above purpose, the present application provides a method for preparing ethyl alkyl ethyl hypophosphite, which comprises the following steps: after the inert gas replaces the air in the reaction kettle, alkyl hypophosphite dialkyl ester, halogen ethane and ruthenium chloride supported catalyst are added; ethyl alkyl ethyl hypophosphite is prepared by stirring at a certain temperature and time, and the product is obtained after filtration, The reaction formula is as follows: .

[0006] The R is selected from any one of methyl, ethyl, propyl, n-butyl, t-butyl, pentyl, hexyl, cyclopentyl, cyclohexyl, phenyl, benzyl or phenethyl.

[0007] The halogenated ethane is selected from any one of bromoethane or chloroethane.

[0008] The halogenated ethane is used in a molar amount of 0.01-0.1 molar equivalent of the diethyl alkylphosphinate, and is any value or interval in the range.

[0009] The supported ruthenium chloride catalyst is silica-supported ruthenium chloride, and the mass fraction of ruthenium chloride is 15-30%.

[0010] The supported ruthenium chloride catalyst is used in a molar amount of 0.05-0.1 molar equivalent of the diethyl alkylphosphinate, and is any value or interval in the range.

[0011] The inert gas is one of dry argon or nitrogen.

[0012] During the reaction, the reaction temperature is 70-90℃, and the reaction time is 1-5 hours. The temperature and reaction time are any value or interval in the range.

[0013] In some preferred cases, the present application provides a method for preparing ethyl methyl ethyl phosphinate, which comprises the following steps: after the inert gas replaces the air in the reaction kettle, diethyl methyl phosphinate, halogenated ethane and supported ruthenium chloride catalyst are added; ethyl methyl ethyl phosphinate is prepared by stirring at a certain temperature and time, and the product is obtained after filtration.

[0014] In the step, the inert gas is one of dry argon or nitrogen.

[0015] Preferably, in the step, the catalyst is used in an amount of 0.01-0.1 equivalent of diethyl methyl phosphinate.

[0016] Preferably, in the step, the supported ruthenium chloride catalyst has a specification of 20%, and is used in an amount of 0.05-0.1 molar equivalent of diethyl methyl phosphinate.

[0017] Preferably, in the step, the reaction temperature is 70-90℃.

[0018] Preferably, in the step, the reaction time is 1-5 hours.

[0019] The temperature, catalyst amount and time parameters of the present application are determined by single variable control method, and the experimental parameters are optimized. The basis of the parameters is the experimental yield.

[0020] The reaction formula of the technical solution of the present application is as follows:

[0021] Compared with the prior art effects, the application has the beneficial effects including: by using chloroethane and a supported ruthenium chloride catalyst, the reaction rate can be regulated by controlling the catalyst type, catalyst dosage and experimental temperature, the reaction concentration does not need to be regulated by adding a solvent, and the operation is simple; after the reaction is completed, the catalyst can be separated from the methyl ethyl hypophosphite by directly filtering, without subsequent separation and purification steps; compared with the catalyst iodine ethane, chloroethane is cheap, easy to obtain and low in toxicity, the low catalytic activity reduces the risk of reaction out of control, and the supported ruthenium chloride catalyst can reduce the reaction temperature. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The gas chromatogram of the internal standard method in Example 6. DETAILED DESCRIPTION

[0023] In order to make the technical solutions of the application clearer and more understandable, the application is further described in detail in combination with reaction equations, gas chromatograms and examples.

[0024] The yield in the following cases is measured by the internal standard method of an Agilent gas chromatograph, the internal standard is tridecane, and the detection conditions are as follows: the detector is FID, the chromatographic column is DB-1 (30 m X 250 um X 0.25 um), the vaporization chamber temperature is 250 DEG C, the detector temperature is 250 DEG C, the nitrogen flow rate is 30 mL / min, the hydrogen flow rate is 40 mL / min, and the air flow rate is 300 mL / min.

[0025] The supported ruthenium chloride catalyst in the following cases is prepared by the following method: 2 g of ruthenium chloride and 20 mL of dichloromethane are added to a dry three-necked flask and stirred, 1 g of triethylamine is added dropwise at 15 ± 2 DEG C, and after the dropwise addition is completed, the temperature is controlled at 20 DEG C and stirring is performed for 1 hour. Then, 10 g of silicon dioxide is added, stirring is performed for 1 hour, and then the powder obtained by concentration under reduced pressure is the 20% supported ruthenium chloride catalyst.

[0026] Example 1-2 An inert gas is blown into a reaction kettle with a magnetic stirrer for 1 minute, 20 g of diethyl methylphosphonate, 0.95 g of chloroethane and 1.12 g of a supported ruthenium chloride catalyst are added, the internal temperature is controlled at 70 DEG C, and stirring is performed for 2 hours to prepare ethyl methyl ethyl hypophosphite, and the product is obtained after filtration. The weight after the reaction is measured, the mass fraction of ethyl methyl ethyl hypophosphite in the completed liquid is measured by the internal standard method, and then the reaction yield is calculated.

[0027]

[0028] Example 3-6 The reaction kettle with magnetic stirrer was purged with nitrogen gas for 1 minute, 20 g of diethyl methylphosphinate, 0.95 g of chloroethane and 1.12 g of supported ruthenium chloride catalyst were added; the internal temperature was controlled, and stirring was carried out for 2 hours to prepare ethyl methyl ethylphosphinate, and the product was obtained after filtration. The weight after reaction was measured, the mass fraction of ethyl methyl ethylphosphinate in the completed liquid was measured by internal standard method, and the reaction yield was calculated.

[0029]

[0030] Figure 1 The gas chromatogram of Example 6 was measured by internal standard method (the retention time of 10.391 min was the internal standard, and the retention time of 11.026 min was ethyl methyl ethylphosphinate).

[0031] Examples 7-10 The reaction kettle with magnetic stirrer was purged with nitrogen gas for 1 minute, 20 g of diethyl methylphosphinate, 0.95 g of chloroethane and 1.12 g of supported ruthenium chloride catalyst were added; the internal temperature was controlled, and stirring was carried out for 2 hours to prepare ethyl methyl ethylphosphinate, and the product was obtained after filtration. The weight after reaction was measured, the mass fraction of ethyl methyl ethylphosphinate in the completed liquid was measured by internal standard method, and the reaction yield was calculated.

[0032]

[0033] Examples 11-13 The reaction kettle with magnetic stirrer was purged with nitrogen gas for 1 minute, 20 g of diethyl methylphosphinate, 0.95 g of chloroethane and 1.12 g of supported ruthenium chloride catalyst were added; the internal temperature was controlled, and stirring was carried out for 2 hours to prepare ethyl methyl ethylphosphinate, and the product was obtained after filtration. The weight after reaction was measured, the mass fraction of ethyl methyl ethylphosphinate in the completed liquid was measured by internal standard method, and the reaction yield was calculated.

[0034]

[0035] The present application is not limited to the above-mentioned embodiments, and any modification, combination, replacement, modification made without departing from the principles of the present application should be considered as equivalent replacement, and is included in the protection scope of the present application.

Claims

1. A process for the catalytic preparation of ethyl ethylalkylphosphinate, characterized in that The method comprises the following steps: After the inert gas replaces the air in the reaction kettle, dialkyl alkylphosphinic acid, haloethane and a supported ruthenium chloride catalyst are added; alkyl ethyl phosphinic acid ethyl ester is prepared by stirring reaction at a certain temperature and time, and the product is obtained after filtration, and the reaction formula is as follows: 。 2. The method according to claim 1, wherein, R is selected from any one of methyl, ethyl, propyl, n-butyl, t-butyl, pentyl, hexyl, cyclopentyl, cyclohexyl, phenyl, benzyl or phenethyl.

3. The method of claim 1, wherein the ethyl alkyl ethylphosphinate is prepared by the reaction of an alkyl ethylphosphinic acid with an alcohol in the presence of a base. The haloethane is selected from any one of bromoethane or chloroethane.

4. The method for preparing alkyl ethyl phosphonate according to claim 1, characterized in that, The molar amount of the chloroethane is 0.01-0.1 molar equivalent of the dialkyl methyl phosphinic acid.

5. The method for preparing alkyl ethyl phosphonate according to claim 1, characterized in that, The supported ruthenium chloride catalyst is silica-supported ruthenium chloride, and the mass fraction of the ruthenium chloride is 15-30%.

6. The method of claim 1, wherein the ethyl alkyl ethylphosphinate is prepared by the process comprising: reacting an alkyl ethylphosphinic acid with an alcohol in the presence of a base to form the ethyl alkyl ethylphosphinate. The molar amount of the chloroethane is 0.05-0.1 molar equivalent of the dialkyl methyl phosphinic acid.

7. The method for preparing alkyl ethyl phosphonate according to claim 1, characterized in that, The inert gas is one of dry argon or nitrogen.

8. The process for preparing ethyl alkyl ethylphosphinate according to claim 1, characterized in that, The reaction temperature is 70-90 DEG C.

9. The method for preparing alkyl ethyl phosphonate according to claim 1, characterized in that, The reaction time is 1-5 hours.

10. A process for the preparation of ethyl methyl ethylphosphinate characterized in that, The method is prepared by any one of claims 1-9.

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