阅读说明：本技术 一种2-噻唑烷酮的制备方法 (Preparation method of 2-thiazolidinone ) 是由 刘小丽 张均 汤丽华 张千峰 于 2019-09-26 设计创作，主要内容包括：本发明公开一种2-噻唑烷酮的制备方法,属于农药化工产品技术领域。该方法以半胱胺盐酸盐和尿素为原料,采用热熔法合成生产2-噻唑烷酮；首先将半胱胺盐酸盐和尿素在反应釜中热熔后进行环合反应,得到热熔法合成产物的混合液；然后向反应釜中加入甲苯进行热萃取,将甲苯的萃取液抽滤过滤至脱溶釜,通过减压蒸馏脱溶,然后将脱溶釜的釜底液转入结晶釜内降温结晶,向结晶釜内加入2-噻唑烷酮晶种制得白色针状微晶产品,白色针状微晶产品在通风环境下风干干燥,制得2-噻唑烷酮。本发明方法简单易控,生产成本较低,没有明显的微废及有害副产物产生,具有显著的环境友好效应。(The invention discloses a preparation method of 2-thiazolidinone, belonging to the technical field of pesticide chemical products. The method takes cysteamine hydrochloride and urea as raw materials, and adopts a hot melting method to synthesize and produce 2-thiazolidinone; firstly, thermally melting cysteamine hydrochloride and urea in a reaction kettle, and then carrying out a cyclization reaction to obtain a mixed solution of a product synthesized by a hot melting method; and then adding toluene into the reaction kettle for thermal extraction, filtering an extract of the toluene to a desolventizing kettle in a suction filtration manner, desolventizing by reduced pressure distillation, transferring a kettle bottom liquid of the desolventizing kettle into a crystallization kettle for cooling crystallization, adding 2-thiazolidinone crystal seeds into the crystallization kettle to prepare a white needle-like microcrystal product, and drying the white needle-like microcrystal product in a ventilated environment by air to prepare the 2-thiazolidinone. The method is simple and easy to control, has low production cost, does not generate obvious micro waste and harmful byproducts, and has obvious environment-friendly effect.)

1. A preparation method of 2-thiazolidone is characterized by comprising the following specific steps:

(1) Adding a certain amount of urea into a reaction kettle, gradually raising the temperature of the reaction kettle to 100-120 ℃, and carrying out hot melting on the urea to a liquid state; opening and maintaining the interior of the reaction kettle to be in micro negative pressure, enabling ammonia gas to smoothly escape and be absorbed by water, absorbing the ammonia tail gas into an absorption tank by using a three-stage method, and finally treating and emptying by using dilute sulfuric acid; continuously and batchwise adding cysteamine hydrochloride into the reaction kettle by a solid feeder, keeping the temperature for 2.5-3.5 hours after adding the cysteamine hydrochloride in 1 hour to obtain a mixed solution of a hot-melting synthetic product, wherein the molar ratio of the cysteamine hydrochloride to the urea is 1: 1.3 to 1.5;

(2) reducing the temperature of the reaction kettle to 80 ℃ in the nitrogen atmosphere, adding toluene into the reaction kettle for 2-3 times to carry out thermal extraction on the mixed solution of the product synthesized by the hot melting method obtained in the step (1), and filtering the extract of the toluene to a desolventizing kettle by suction filtration;

(3) Starting a negative pressure pump to ensure that the temperature of the desolventizing kettle is 80-90 ℃ and the pressure is 0.2-1 MPa, desolventizing by reduced pressure distillation, then transferring the kettle bottom liquid of the desolventizing kettle into a crystallization kettle for cooling crystallization, adding 2-thiazolidone seed crystal into the crystallization kettle, keeping the temperature for 2-4 hours to prepare a white acicular microcrystal product under the temperature condition of 0-10 ℃, performing centrifugal separation, collecting and applying filtrate, recycling desolventizing and crystallizing, and drying the white acicular microcrystal product by air in a ventilation environment to obtain a product: 2-thiazolidinone.

2. A process for preparing 2-thiazolidinone according to claim 1 wherein the rest of the reactor after thermal extraction in step (2) is washed with 95% industrial ethanol and dried to obtain ammonium chloride as by-product.

3. A process for preparing 2-thiazolidinone according to claim 1 wherein the temperature for vacuum distillation and desolventizing in step (3) is 87-89 ℃, and the distilled amount of toluene is 75 wt%.

The technical field is as follows:

The invention belongs to the technical field of pesticide chemical products, and particularly relates to a preparation method of 2-thiazolidinone.

background art:

2-thiazolidinone (2-thiazolidinone) can be directly used as a bactericide, an insecticide and a plant growth regulator, and is also an important intermediate of pesticides, medicines and dyes, for example, the 2-thiazolidinone is an important intermediate of good nematocide fosthiazate. With the development of heterocyclic pesticides, 2-thiazolidinone is very important in the innovation of heterocyclic pesticides, at present, most of pesticides used at home and abroad are organic phosphine pesticides, and although the pesticides have the characteristics of high pesticide effect, convenience in use, systemic action and easiness in degradation under natural conditions, the high organic phosphine-containing pesticides have extremely high toxicity, so that the use of the high organic phosphine-containing pesticides is forbidden in many countries. A novel pesticide, namely fosthiazate, is developed by Japan stone original industry company, is a nematicide with high efficiency, low toxicity, wide popularization and safety, has the function of preventing and treating plant nematode diseases, and is very important at home and abroad; among them, 2-thiazolidinone is an important intermediate for synthesizing fosthiazate, so it is also of great interest to optimize the synthesis and production process of 2-thiazolidinone, especially relating to environmental protection and other factors.

at present, the synthesis path of 2-thiazolidinone is more, and many documents are reported, such as an oxidation method using 2-thiazolidinethione as a starting material, a condensation method using cysteamine as a raw material, a condensation method using 2-aminoethyl sulfate as a starting material, and the like; the 2-thiazolidone ketone is synthesized by taking the 2-thiazolidone ketone as an initial raw material and oxidizing the 2-thiazolidone ketone with hydrogen peroxide, phosgene or ethylene oxide, but the reaction is violent and is not easy to control, and the generated by-product is not easy to treat; secondly, the synthesis process flow of the 2-aminoethyl sulfate is complex, the process path flow is long, the requirement of a prepared treatment device is harsh, and the production cost is high.

The invention content is as follows:

The invention provides a preparation method of 2-thiazolidinone aiming at the problems in the prior art. The method for synthesizing and producing the 2-thiazolidone by using the cysteamine hydrochloride and the urea as raw materials and adopting the hot melting method is simple, easy to control, low in production cost, free of obvious micro waste and harmful byproducts and obvious in environment-friendly effect.

The preparation method of the 2-thiazolidone provided by the invention comprises the following specific steps:

(1) adding a certain amount of urea into a reaction kettle, gradually raising the temperature of the reaction kettle to 100-120 ℃, and carrying out hot melting on the urea to a liquid state; opening and maintaining the interior of the reaction kettle to be in micro negative pressure, enabling ammonia gas to smoothly escape and be absorbed by water, absorbing the ammonia tail gas into an absorption tank by using a three-stage method, and finally treating and emptying by using dilute sulfuric acid; continuously and batchwise adding cysteamine hydrochloride into the reaction kettle by a solid feeder, keeping the temperature for 2.5-3.5 hours after adding the cysteamine hydrochloride in 1 hour to obtain a mixed solution of a hot-melting synthetic product, wherein the molar ratio of the cysteamine hydrochloride to the urea is 1: 1.3 to 1.5.

(2) And (2) reducing the temperature of the reaction kettle to 80 ℃ in the nitrogen atmosphere, adding toluene into the reaction kettle for three times to carry out thermal extraction on the mixed liquid of the product synthesized by the hot melting method obtained in the step (1), and filtering the extract liquid of the toluene to a desolventizing kettle by suction filtration.

(3) starting a negative pressure pump to ensure that the temperature of the desolventizing kettle is 80-90 ℃ and the pressure is 0.2-1 MPa, removing a solvent through reduced pressure distillation, transferring kettle bottom liquid of the desolventizing kettle into a crystallization kettle for cooling crystallization, adding 2-thiazolidone seed crystal into the crystallization kettle, keeping the temperature for 2-4 hours to prepare a white needle-shaped microcrystal product under the temperature condition of 0-10 ℃, performing centrifugal separation, collecting filtrate for application, recycling desolventizing and crystallizing, and drying the white needle-shaped microcrystal product in a ventilation environment in a wind-dry mode to obtain a target product: 2-thiazolidinone, and the purity of the product can be determined by measuring the melting range by a melting point instrument.

In the invention, the residual part in the reaction kettle after the thermal extraction in the step (2) is washed by 95 percent of industrial ethanol and dried to obtain an ammonium chloride byproduct. The industrial ethanol used for washing is completely distilled and can be recycled and reused. In the step (3), the temperature of the reduced pressure distillation and desolventizing is 87-89 ℃, and the distillation amount of the toluene is 75 wt%, so that the subsequent control is easy to crystallize, and the production efficiency is improved.

During the cyclization reaction after hot melting, a high-power motor (provided with a speed reducer) is required to control the stirring speed gradually through the conversion process of liquid, colloid and viscous pasty solid, a motor with 11.5-13.5 Kw/h is generally adopted, the stirring speed is gradually reduced from high in principle, and the heating condition of the motor is noticed at the later stage. The purpose of the micro negative pressure is to completely absorb a large amount of ammonia gas generated by cyclization reaction into tail gas.

During extraction, toluene can be added for 2-3 times, so that the product concentration of the first extraction liquid is reduced, and the extraction liquid at the back can easily pass through a ball valve controller to discharge the extraction liquid; in addition, the order of extraction and filter pressing is adopted, namely most of the extraction liquid is discharged firstly, and then a small part of the extraction liquid together with the ammonium chloride is filtered and pressed and filtered.

The primary mother liquor after crystallization can be continuously left in the crystallization kettle, can also enter the desolventizing kettle for suction filtration and desolventizing and then enter the crystallization kettle, can be combined with the toluene solution of the product after the second desolventizing, and is continuously used for crystallizing the 2-thiazolidinone product at low temperature.

the invention has the following technical characteristics:

1. The whole reaction process is simple, the used reaction device is easy to build, the operation is simple and convenient, the yield of the product is high, the industrial popularization is facilitated, and the factory production has the maximum economic benefit.

2. The needed raw materials are cheap and easy to obtain, the used raw materials of cysteamine hydrochloride and urea are industrialized raw materials which can be produced in a large scale, and the toluene solvent used in the invention can be recycled, so that the cost is saved, and the economic requirement is met.

3. The obtained by-product ammonia gas is absorbed into an ammonia water by-product by water, and compared with the by-products generated by other methods, the by-product is better treated, and hydrochloric acid water can also be used for absorbing into an ammonium chloride solid by-product, so that the method is green and environment-friendly, and has less pollution.

4. The used toluene solvent and the industrial ethanol solution used for treating the byproducts can be recycled, so that the aim of saving resources can be fulfilled, and the method is a green recycling production process of a clean process.

5. The obtained by-product ammonium chloride can be sold as an industrial grade ammonium chloride product after being treated so as to obtain additional economic benefit.

Description of the drawings:

FIG. 1 is a schematic view of a process flow of a method for preparing 2-thiazolidinone of the present invention.

the specific implementation mode is as follows: