CN109912651B

CN109912651B - Preparation method of benzyltriphenylphosphonium chloride

Info

Publication number: CN109912651B
Application number: CN201910285091.0A
Authority: CN
Inventors: 黄勇; 程大军; 程杰
Original assignee: ZIGONG TIANLONG CHEMICAL CO Ltd
Current assignee: ZIGONG TIANLONG CHEMICAL CO Ltd
Priority date: 2019-04-10
Filing date: 2019-04-10
Publication date: 2021-09-07
Anticipated expiration: 2039-04-10
Also published as: CN109912651A

Abstract

The invention belongs to the technical field of fine chemical engineering, and particularly relates to a preparation method of benzyltriphenylphosphonium chloride. According to the method, triphenylphosphine and benzyl chloride are used as raw materials in a mixed solution of water and benzyl chloride, the reflux reaction is carried out by utilizing the reaction heat release at a certain initial temperature, and the benzyltriphenylphosphonium chloride is obtained by standing, layering, heat preservation, liquid separation, micro-membrane filtration, cooling crystallization, centrifugal separation and vacuum drying. The invention has simple process, rapid reaction, mild condition, high purity and high yield. In the method, the solvent water and the excessive benzyl chloride are recycled, and the reaction is promoted by utilizing the reaction heat release, so that the energy conservation and emission reduction are realized, the cost is reduced, and the industrial production is easier. The content of the synthesized benzyl triphenyl phosphonium chloride is more than 99 percent, and the reaction yield reaches 98 percent.

Description

Preparation method of benzyltriphenylphosphonium chloride

Technical Field

The invention belongs to the technical field of fine chemical engineering, relates to a preparation process of a fluororubber crosslinking accelerator, and particularly relates to a preparation method of benzyltriphenylphosphonium chloride.

Background

The benzyl triphenyl phosphonium chloride is an organic chemical substance, is mainly used as a fluororubber vulcanization accelerator and a phase transfer catalyst, and can also be used as a medicine, an organic synthesis intermediate and the like. In recent years, new applications thereof are continuously developed, and the demand thereof is increasing year by year.

At present, the main synthesis method is a direct synthesis method of benzyl chloride triphenylphosphine in an organic solvent, the method has violent reaction, is easy to cause the dissipation of the solvent and benzyl chloride, is difficult to separate a product from a raw material, needs repeated recrystallization to improve the purity, produces dangerous solid wastes to pollute the environment, and has the defects of high energy consumption and low yield. Utility model patent CN201621275573.6 discloses a reflux unit of benzyl triphenyl phosphorus chloride, and the setting of this backward flow case can effectively alleviate steam too much and lead to the too big problem of reation kettle internal pressure in the reation kettle, but does not solve other problems in the reaction.

Disclosure of Invention

Aiming at the technical problems, the invention provides a preparation method of benzyltriphenylphosphonium chloride. The method has simple process, rapid reaction and mild conditions; the obtained product has high purity and high yield; the preparation process has no three wastes, and the solvent water and the benzyl chloride can be recycled. The reaction system in the method makes full use of the characteristics that the triphenylphosphine serving as a raw material is insoluble in water and soluble in benzyl chloride, the benzyl triphenyl phosphonium chloride serving as a product is very soluble in water, the benzyl chloride is not dissolved in a water layer, and the like, so that the product is separated; the reaction system temperature is kept by utilizing the reaction heat release, the reaction system temperature is controlled by utilizing the water reflux, the dissipation of benzyl chloride and the occurrence of side reaction caused by overhigh temperature are avoided, the tail gas treatment steps are reduced, and the industrial production is easy. The content of the synthesized benzyl triphenyl phosphonium chloride reaches more than 99 percent, and the reaction yield reaches 98 percent.

In order to achieve the above purpose, the technical scheme of the invention is as follows:

a preparation method of benzyltriphenylphosphonium chloride comprises the following steps:

(1) adding water (recovered water or mother liquor) and excessive benzyl chloride into a reaction kettle through a liquid transfer pump, then starting circulating liquid in a jacket of the reaction kettle, and heating the liquid in the kettle to 80-85 ℃.

(2) Slowly adding triphenylphosphine particles through a vibration feeder, quickly dissolving and reacting to release heat, controlling the reflux temperature of the water phase to be lower than 110 ℃, dissolving benzyl triphenyl phosphonium chloride generated by benzyl chloride and triphenylphosphine into the water phase, and after the addition, carrying out reflux reaction for 1 hour.

(3) And after the reaction is completed, keeping the temperature in the kettle at 80-85 ℃, standing for layering, wherein the upper layer is an organic phase, and the lower layer is a water phase, continuously putting the lower water phase into a tetrafluoro micro-membrane filter, and putting the filtered water solution into the reaction kettle for cooling and crystallization. In the step, the pore diameter of the PTFE micro-membrane filter is 0.1-0.5 micron, the temperature is kept at 80-85 ℃, and the stirring speed in the reaction kettle is kept at 80-120 rpm.

(4) And after cooling to room temperature, continuously putting the mixture of the water in the kettle and the benzyltriphenylphosphonium chloride into a tetrafluoro membrane type centrifuge for separation to obtain a crude benzyltriphenylphosphonium chloride product, and returning the centrifugal mother liquor for recycling. The pore diameter of a membrane in the tetrafluoro membrane type centrifugal machine is 1-5 microns, so that crystals cannot penetrate through the membrane and mother liquor can be quickly separated; the traditional cloth bag type centrifugal pocket cannot be used in the step, and fibers on the centrifugal pocket are prevented from being mixed in the product.

(5) And (3) putting the separated benzyltriphenylphosphonium chloride crude product into an enamel shaking oven, starting water spraying vacuum, carrying out vacuum drying at the temperature of 95-105 ℃ to obtain a finished product, and distilling to recover the aqueous solution and trace benzyl chloride for recycling. The enamel rocking oven can effectively avoid corrosion of the product and benzyl chloride to metal, and avoid impurities in the product and pollution to the recovered water and benzyl chloride; the vacuum drying aims to remove water and trace benzyl chloride, the water spraying vacuum suction amount is large, steam backflow can be effectively avoided, the water and trace benzyl chloride can be effectively removed at the temperature of 95-105 ℃, and meanwhile the risk that the product is agglomerated and the quality of the product is reduced due to overhigh temperature is avoided.

The reaction in the preparation method is carried out in two stages, wherein in the first stage, the temperature is increased to 80-85 ℃ by electric heating in a reaction kettle jacket, and the temperature reaches the lowest temperature of the rapid reaction of triphenylphosphine and benzyl chloride; in the second stage, the heat released by the reaction of triphenylphosphine and benzyl chloride is used to heat and reflux water, so as to promote the reaction and control the temperature of the reaction system to be lower than 110 ℃, thereby avoiding the dissipation of organic gas and side reaction.

The production process of triallyl cyanurate uses the mixture of pure benzyl chloride and recovered benzyl chloride. In the invention, triphenylphosphine and benzyl chloride react under the condition of an aqueous phase solvent, a lower aqueous phase is obtained by heat preservation, standing, liquid separation and separation, wherein the weight of the benzyl chloride is 2-3 times that of the triphenylphosphine, and the weight of water is 4-5 times that of the triphenylphosphine, the triphenylphosphine can be rapidly dispersed and reacted according to the proportion, and meanwhile, the generated benzyltriphenylphosphonium chloride can be rapidly dissolved into the aqueous phase.

To suppress the decomposition reaction (which reduces yield), the reactants are mixed rapidly and thoroughly, so that the addition time, which corresponds to the largest part of the total reaction time, is kept to a minimum. The total reaction time (time of addition of reactants to benzyl chloride and time of subsequent reaction) is preferably not more than 3 hours, and preferably less than 2 hours.

In view of the high reaction enthalpy, strong reflux cooling is required, for example with cooling with industrial brine, in order to achieve short reaction times. On an industrial scale, heat removal by means of an external cooling circuit with suitable heat exchangers and circulation pumps is particularly effective.

Preferably, standing and layering at 80-85 ℃ after the reaction is finished, continuously putting the lower-layer aqueous phase into a tetrafluoro microfilm filter with the temperature of 80-85 ℃ to prevent the crystallization of the product and the rapid evaporation of water, wherein the temperature is preferably 85 ℃; and (3) putting the filtered aqueous solution into a reaction kettle, cooling, keeping stirring for 80-120 r/min, stirring for crystallization, and enabling fine crystals to be separated out to avoid the phenomenon of wrapping, wherein the stirring is preferably 100 r/min.

In the present application, regarding the selection of the raw materials: the water phase is selected to replace the recycling of an organic chemical solvent, and the benzyl chloride is a mixture of pure benzyl chloride and recovered benzyl chloride, so that the production cost is reduced, and the product yield is improved; the preferable diameter of triphenylphosphine is 1-5 mm small round sphere granular product, and the triphenylphosphine can be quickly immersed into the liquid surface for reaction, so that dust pollution in the feeding process is avoided. The change of the raw materials improves the production and operation environment of workers and reduces the harm to the environment.

In the solid-liquid reaction: and adding excessive benzyl chloride into the reaction kettle, wherein the excessive benzyl chloride can ensure that the triphenylphosphine reacts completely, and slowly adding the triphenylphosphine through a vibration feeder to generate the benzyltriphenylphosphonium chloride. The benzyl chloride is liquid at normal temperature, the triphenylphosphine is solid particles at normal temperature, solid and liquid directly and fully react, and the excessive benzyl chloride is simultaneously used as a reactant and an organic solvent, so that the possibility is provided for recycling.

Liquid separation and purification process: after the reaction is finished, the product is dissolved in an aqueous solution at the temperature of 80-85 ℃, benzyl chloride and the aqueous solution are obviously layered, and the specific gravity of the aqueous solution is higher at the lower part. Continuously putting the water solution with the temperature of 80-85 ℃ in the kettle into a tetrafluoro column core type filter with a jacket with the temperature of 80-85 ℃, and enabling the water solution to be clear and transparent through a 0.1-0.5 micron tetrafluoro filter membrane; and cooling and crystallizing the mixture in a crystallization kettle under the stirring of 80-120 rpm to separate out fine crystals, so that the influence of coarse crystal wrapping on the quality is avoided.

And (3) centrifugal separation process: after cooling to room temperature, continuously putting the mixture of water and benzyltriphenylphosphonium chloride in the kettle into a tetrafluoro membrane type centrifuge, wherein the pore diameter of a membrane is 1-5 microns, so that crystals cannot penetrate through the membrane and mother liquor can be quickly separated; the traditional cloth bag type centrifugal pocket is not used, and the fiber on the centrifugal pocket is prevented from being mixed in the product.

And (3) vacuum drying process: and (3) putting the benzyl triphenyl phosphine chloride crude product into an enamel shaking oven, starting water spraying vacuum, carrying out vacuum drying at the temperature of 95-105 ℃ to obtain a finished product, and recycling the aqueous solution and trace benzyl chloride for recycling. The enamel rocking oven can effectively avoid corrosion of the product and benzyl chloride to metal, and avoid impurities in the product and pollution to the recovered water and benzyl chloride; the vacuum drying aims to remove water and trace benzyl chloride, the water spraying vacuum suction amount is large, steam backflow can be effectively avoided, the water and trace benzyl chloride can be effectively removed at the temperature of 95-105 ℃, and meanwhile the risk that the product is agglomerated and the quality of the product is reduced due to overhigh temperature is avoided.

Compared with the prior art, the invention has the beneficial effects that:

the invention has the advantages of simple process, rapid reaction, mild conditions, high purity and high yield.

The invention uses the mixed system of benzyl chloride and water as the reaction solution, so that the reaction product is easier to separate, the reaction time is shortened, the yield is improved, the self heat release of the reaction system is fully utilized, the energy consumption is reduced, and the invention has the advantages of simple steps, high efficiency, low product cost and the like.

And (III) the solvent water and the excessive benzyl chloride are recycled, the reaction is promoted to be carried out by utilizing the exothermic reaction, and the like, so that the energy conservation and emission reduction are realized, the cost is reduced, and the industrial production is easy to realize.

And (IV) compared with the currently known method, the method is easy to implement, has lower technical complexity and does not have the three-waste problem and the recrystallization step.

Fifthly, the content of the synthesized benzyl triphenyl phosphonium chloride is more than 99 percent, and the reaction yield reaches 98 percent.

Detailed Description

The present invention is further illustrated by the following examples, but the scope of the present invention is not limited to the specific embodiments. The invention extends to any novel feature or any novel combination of features disclosed in this specification and any novel method or process steps or any novel combination of features disclosed.

Example 1:

in a 1000L enamel reactor with jacket-heated and cryogenically cooled return pipe, 400.0 kg water (recycled mother liquor), 200.0kg benzyl chloride (314% excess) were initially charged; stirring is started, the jacket is heated, the temperature of the solution in the kettle is heated to 85 ℃, and then the jacket stops heating. And then adding 100.0 kg of granular triphenylphosphine in total, slowly adding the granular triphenylphosphine through a vibration feeder, quickly dissolving the triphenylphosphine and reacting to release heat, controlling the temperature in the kettle by refluxing the water phase to generate the benzyltriphenylphosphonium chloride, wherein the total addition time is about 60 minutes. For complete conversion, starting a jacket for heating, keeping the temperature of liquid in the reaction kettle at 80-85 ℃, continuously stirring for reaction for 30 minutes, stopping stirring, continuously keeping the temperature of liquid in the kettle at 80-85 ℃ for 30 minutes, continuously putting the lower-layer water phase into a tetrafluoro column core type filter with the jacket insulating at 80-85 ℃, and enabling the water solution to be clear and transparent through a 0.2 micron tetrafluoro filter membrane; stirring, cooling and crystallizing in a crystallizing kettle at a stirring speed of 100 rpm to precipitate fine crystals. After cooling to room temperature, continuously putting the mixture of water in the kettle and benzyltriphenylphosphonium chloride into a tetrafluoro membrane type centrifuge, wherein the pore diameter of the membrane is 2 microns; and (3) putting the benzyl triphenyl phosphine chloride crude product into an enamel shaking oven, starting water spraying vacuum, carrying out vacuum drying at the temperature of 95-105 ℃, recovering the aqueous solution and trace benzyl chloride for recycling, and reacting to obtain 145.59 kg of finished product, wherein the yield is 98.59%, and the purity is 99.23%.

Example 2:

the preparation of benzyltriphenylphosphonium chloride was carried out in the same manner as in example 1, except that 500 kg of water (recycled mother liquor) were initially metered in. After the reaction process and conditions specified in example 1, 144.86 kg of finished product was obtained, the yield of benzyltriphenylphosphonium chloride product was 98.08%, and the purity was 99.61%.

Comparative example 1:

the preparation of benzyltriphenylphosphonium chloride was carried out using the reaction procedure and conditions specified in example 1, with the difference that the amount of water initially metered in was 300 kg (recycled mother liquor). In the reaction process, crystals are separated out, and part of products are removed by an organic filter membrane to obtain 134.38 kg of finished products, wherein the yield is 91.27% and the purity is 99.29%.

Comparative example 2:

the preparation of benzyltriphenylphosphonium chloride was carried out by working up the reaction procedures and conditions specified in example 1, with the difference that the benzyl chloride was 100kg, only in 107% excess. After benzyl chloride is dispersed by the water phase, triphenylphosphine cannot fully contact with the benzyl chloride, triphenylphosphine cannot be rapidly dispersed and reacted in the reaction process, an organic layer is turbid, and it is proved that part of triphenylphosphine cannot be completely reacted, 116.65 kg of a finished product is obtained, the yield is 79.54%, and the purity is 96.38%.

The above examples are only preferred embodiments of the patent, but the scope of protection of the patent is not limited thereto. It should be noted that, for those skilled in the art, without departing from the principle of this patent, several improvements and modifications can be made according to the patent solution and its patent idea, and these improvements and modifications should also be regarded as the protection scope of this patent.

Claims

1. A preparation method of benzyltriphenylphosphonium chloride is characterized by comprising the following steps:

(1) adding recovered water or mother liquor into a reaction kettle, adding benzyl chloride, starting circulating liquid in a jacket of the reaction kettle, and heating liquid in the kettle to 80-85 ℃;

(2) slowly adding triphenylphosphine particles through a vibration feeder, quickly dissolving and reacting to release heat, controlling the temperature of the solution to be lower than 110 ℃ by water phase reflux, dissolving benzyl triphenyl phosphonium chloride generated by benzyl chloride and triphenylphosphine into the water phase, and performing reflux reaction for 1 hour after the addition is finished, wherein the weight of the benzyl chloride is 2-3 times of that of the triphenylphosphine;

(3) after the reaction in the step (2) is completed, keeping the temperature in the kettle at 80-85 ℃ for standing and layering, wherein the upper layer is an organic phase, the lower layer is a water phase, continuously putting the lower water phase into a tetrafluoro micro-membrane filter for filtering, putting the filtered water solution into the reaction kettle for cooling, stirring and crystallizing, and keeping stirring at 80-120 rpm in the cooling, stirring and crystallizing process;

(4) after the mixture of the water in the kettle and the benzyltriphenylphosphonium chloride is cooled to room temperature, continuously putting the mixture into a tetrafluoro membrane type centrifuge for separation to obtain a crude product of the benzyltriphenylphosphonium chloride, and returning the centrifugal mother liquor for recycling;

(5) loading the separated benzyl triphenyl phosphonium chloride crude product into an enamel shaking oven, starting water spraying vacuum, carrying out vacuum drying at the temperature of 95-105 ℃ to obtain a finished product, and distilling and recovering the water solution and trace benzyl chloride for recycling;

the weight of the water is 4-5 times of that of the triphenylphosphine; in the step (3), the temperature of the tetrafluoro microfilm filter is kept at 80-85 ℃, and the pore diameter of the tetrafluoro microfilm filter is 0.1-0.5 micron; the pore diameter of the membrane in the tetrafluoro membrane type centrifuge in the step (4) is 1-5 microns; the total reaction time, including the time of addition of reactants to the phosphine chloride and the time of subsequent reactions, was limited to 3 hours.

2. The method for preparing benzyltriphenylphosphonium chloride according to claim 1, wherein: in the step (3), the stirring speed is kept at 80-120 r/min in the cooling, stirring and crystallizing process.