阅读说明：本技术 一种4,6-二氯嘧啶的制备方法 (Preparation method of 4, 6-dichloropyrimidine ) 是由 李利强 王凯 杨树仁 骆广生 崔淑娜 单海山 于 2020-06-01 设计创作，主要内容包括：本发明公开了一种4,6-二氯嘧啶的制备方法,包括以下步骤：(1)将4,6-二羟基嘧啶、催化剂溶于极性溶剂,混合为含有4,6-二羟基嘧啶的混合溶液；(2)将氯气或者液氯加入到混合溶液中,反应获得含有4,6-二氯嘧啶的混合溶液；(3)对含有4,6-二氯嘧啶的混合溶液进行蒸馏脱除溶剂、脱酸、蒸馏回收副产的三氯氧磷,得到4,6-二氯嘧啶粗品；(5)将所述4,6-二氯嘧啶粗品萃取分离、闪蒸出溶剂,4,6-二氯嘧啶被保留在水相中；将水相降温冷却结晶,脱水处理得到4,6-二氯嘧啶产品。本发明采用低价易得的催化剂,能显著提高反应效率；以氯气/液氯为氯化剂,大大减少了过程的危险性,并且副产高附加值产品三氯氧磷。(The invention discloses a preparation method of 4, 6-dichloropyrimidine, which comprises the following steps: (1) dissolving 4, 6-dihydroxypyrimidine and a catalyst in a polar solvent, and mixing to obtain a mixed solution containing 4, 6-dihydroxypyrimidine; (2) adding chlorine or liquid chlorine into the mixed solution, and reacting to obtain a mixed solution containing 4, 6-dichloropyrimidine; (3) distilling the mixed solution containing 4, 6-dichloropyrimidine to remove the solvent, deacidifying, distilling and recovering the byproduct phosphorus oxychloride to obtain a crude product of the 4, 6-dichloropyrimidine; (5) extracting and separating the crude 4, 6-dichloropyrimidine, and flashing off a solvent, wherein the 4, 6-dichloropyrimidine is retained in an aqueous phase; cooling and crystallizing the water phase, and dehydrating to obtain the 4, 6-dichloropyrimidine product. The invention adopts the catalyst which is low in price and easy to obtain, and can obviously improve the reaction efficiency; chlorine gas/liquid chlorine is used as a chlorinating agent, so that the danger of the process is greatly reduced, and a high value-added product, namely phosphorus oxychloride, is produced as a byproduct.)

1. A preparation method of 4, 6-dichloropyrimidine is characterized by comprising the following steps:

(1) dissolving 4, 6-dihydroxypyrimidine in a polar solvent, dissolving a Lewis acid catalyst or an organic acid catalyst taking an inorganic oxide as a carrier in the polar solvent, and mixing to obtain a mixed solution containing the 4, 6-dihydroxypyrimidine;

(2) adding chlorine or liquid chlorine into a mixed solution containing 4, 6-dihydroxypyrimidine, wherein the molar ratio of 4, 6-dihydroxypyrimidine/phosphorus trichloride/chlorine simple substance/is as follows: 1: 1.5-8: 2-3.5: 2-2.8, keeping the reaction temperature at 50-120 ℃, the pressure at 0-0.3 MPa and the reaction time at 0.5-4 hours to obtain a mixed solution containing 4, 6-dichloropyrimidine;

(3) distilling the mixed solution containing 4, 6-dichloropyrimidine to remove the polar solvent and deacidify;

(4) keeping the temperature at 70-90 ℃, and continuously distilling and recovering the byproduct phosphorus oxychloride under the condition that the vacuum degree is less than or equal to-0.09 MPa to obtain a crude product of 4, 6-dichloropyrimidine;

(5) dissolving the 4, 6-dichloropyrimidine crude product in water with the volume of 2-10 times, adjusting the pH value to 5-7, adding an organic solvent with the volume of 1-2 times that of the dissolved water solution, and extracting and separating to obtain a water phase and an organic phase;

(6) dropwise adding the organic phase obtained by extraction into hot water at the temperature of 80-100 ℃ to flash off the organic solvent, and keeping the 4, 6-dichloropyrimidine in the water phase; cooling and crystallizing the water phase, and dehydrating to obtain the 4, 6-dichloropyrimidine product.

2. A process for the preparation of 4, 6-dichloropyrimidine as claimed in claim 1 comprising: the polar solvent comprises at least one of aromatic hydrocarbon, halogenated aromatic hydrocarbon, aromatic hydrocarbon nitrate, aromatic hydrocarbon sulfonate, halogenated hydrocarbon, cyclane and halogenated matters thereof, and phosphoryl chloride.

3. A process for the preparation of 4, 6-dichloropyrimidine as claimed in claim 2 wherein: the polar solvent comprises at least one of toluene, ethylbenzene, xylene, cyclohexane, methylcyclohexane, chlorobenzene, dichlorobenzene, nitrobenzene, dichloromethane, chloroform, carbon tetrachloride, dichloroethane, butyl ether, anisole, phosphorus oxychloride and phosphorus trichloride.

4. A process for the preparation of 4, 6-dichloropyrimidine as claimed in claim 3 wherein: the polar solvent is phosphorus oxychloride.

5. A process for the preparation of 4, 6-dichloropyrimidine as claimed in claim 1 comprising: the Lewis acid catalyst comprises at least one of aluminum trichloride, magnesium chloride, aluminum chloride and titanium tetrachloride; the organic acid catalyst comprises at least one of triphenyl phosphine oxide and phosphate ester in organic phosphoric acid; the inorganic oxide carrier is a porous or microporous silicon dioxide ball.

6. A process for the preparation of 4, 6-dichloropyrimidine as claimed in claim 1 comprising: the dosage of the catalyst is 0.5-4 wt% of 4, 6-dihydroxypyrimidine.

7. A process for the preparation of 4, 6-dichloropyrimidine as claimed in any one of claims 1 to 6 wherein: in the step (2), the reaction is terminated until the content of 4, 6-dihydroxypyrimidine in the mixed solution is less than 1 wt%.

8. A process for the preparation of 4, 6-dichloropyrimidine as claimed in claim 1 comprising: in the step (2), the reaction temperature is 65-90 ℃.

9. A process for the preparation of 4, 6-dichloropyrimidine as claimed in claim 1 comprising: in the step (5), the organic solvent used for extraction includes at least one of toluene, ethylbenzene, xylene, cyclohexane, methylcyclohexane, chlorobenzene, dichlorobenzene, nitrobenzene, dichloromethane, chloroform, carbon tetrachloride, dichloroethane, butyl ether, and anisole.

10. A process for the preparation of 4, 6-dichloropyrimidine as claimed in claim 1 comprising: and (6) recovering and recycling the organic solvent flashed off.

Technical Field

The invention relates to the technical field of organic chemical synthesis, in particular to a 4, 6-dichloropyrimidine synthesis technology.

Background

4, 6-dichloropyrimidine is an important organic chemical intermediate, and is used for producing sulfanilamide products such as sulfamethazine, sulfamethizole, sulfametoxin, sulfanilamide-6-methoxypyrimidine and the like in the aspect of medicine; is used for synthesizing the strobilurin fungicide in the aspect of pesticides.

Among the known processes for preparing 4, 6-dichloropyrimidine, the most important process is to react 4, 6-dichloropyrimidine, phosphorus oxychloride and an organic base at a certain temperature, distill the obtained mixture to recover phosphorus oxychloride, extract the mixture with an organic solvent in ice water, and recover the solvent to obtain the product 4, 6-dichloropyrimidine (the synthesis research and application of 4, 6-dichloropyrimidine in Poplar, Huzhulin, 4, 6-dichloropyrimidine, 2012,41 (11: 1995-. The method has the main disadvantages that the organic alkali in the reaction process is difficult to recover, the waste water yield is high, the alkali consumption is high, the waste of useful phosphorus resources is serious, the organic alkali is finally converted into the phosphate with low value, and the waste water treatment cost is high.

In order to solve the above problems, chinese patent publication No. CN106187913A discloses a method for preparing 4, 6-dichloropyrimidine, in which phosgene is used instead of phosphorus oxychloride for chlorination, which can solve some problems, but also causes problems of low yield, poor safety, and poor operability in an industrial process.

Chinese patent CN105439963B discloses a method for preparing 4, 6-dichloropyrimidine, which is similar to the method disclosed in the patent, wherein a chlorinating agent adopts triphosgene and diphosgene, and the problems of potential safety hazard and low yield are also existed.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: aiming at the defects in the prior art, the preparation method of the 4, 6-dichloropyrimidine is safe in production, free of wastewater discharge, high in reaction yield and low in production cost.

In order to solve the technical problems, the technical scheme of the invention is as follows:

a preparation method of 4, 6-dichloropyrimidine comprises the following steps:

(1) dissolving 4, 6-dihydroxypyrimidine in a polar solvent, dissolving a Lewis acid catalyst or an organic acid catalyst taking an inorganic oxide as a carrier in the polar solvent, and mixing to obtain a mixed solution containing the 4, 6-dihydroxypyrimidine;

(2) adding chlorine or liquid chlorine into a mixed solution containing 4, 6-dihydroxypyrimidine, wherein the molar ratio of 4, 6-dihydroxypyrimidine/phosphorus trichloride/chlorine simple substance/is as follows: 1: 1.5-8: 2-3.5: 2-2.8, keeping the reaction temperature at 50-120 ℃, the pressure at 0-0.3 MPa and the reaction time at 0.5-4 hours to obtain a mixed solution containing 4, 6-dichloropyrimidine;

(3) distilling the mixed solution containing 4, 6-dichloropyrimidine to remove the polar solvent and deacidify;

(4) keeping the temperature at 70-90 ℃, and continuously distilling and recovering the byproduct phosphorus oxychloride under the condition that the vacuum degree is less than or equal to-0.09 MPa to obtain a crude product of 4, 6-dichloropyrimidine;

(5) dissolving the 4, 6-dichloropyrimidine crude product in water with the volume of 2-10 times, adjusting the pH value to 5-7, adding an organic solvent with the volume of 1-2 times that of the dissolved water solution, and extracting and separating to obtain a water phase and an organic phase;

(6) dropwise adding the organic phase obtained by extraction into hot water at the temperature of 80-100 ℃ to flash off the organic solvent, and keeping the 4, 6-dichloropyrimidine in the water phase; cooling and crystallizing the water phase, and dehydrating to obtain the 4, 6-dichloropyrimidine product.

The reaction equation of the invention is as follows:

preferably, the polar solvent comprises at least one of aromatic hydrocarbon, halogenated aromatic hydrocarbon, aromatic hydrocarbon nitrate, aromatic hydrocarbon sulfonate, halogenated hydrocarbon, cyclane and halogenated compound thereof, and phosphorus oxychloride.

In a further preferred embodiment, the polar solvent includes at least one of toluene, ethylbenzene, xylene, cyclohexane, methylcyclohexane, chlorobenzene, dichlorobenzene, nitrobenzene, dichloromethane, chloroform, carbon tetrachloride, dichloroethane, butyl ether, anisole, phosphorus oxychloride, and phosphorus trichloride.

As a still further preferable technical solution, the polar solvent is phosphorus oxychloride.

Preferably, the lewis acid catalyst comprises at least one of aluminum trichloride, magnesium chloride, aluminum chloride and titanium tetrachloride; the organic acid catalyst comprises at least one of triphenyl phosphine oxide and phosphate ester in organic phosphoric acid; the inorganic oxide carrier is a porous or microporous silicon dioxide ball.

Preferably, the amount of the catalyst is 0.5-4 wt% of the 4, 6-dihydroxypyrimidine.

As an improved technical scheme, in the step (2), the reaction is terminated when the content of the 4, 6-dihydroxypyrimidine in the mixed solution is lower than 1 wt%.

As a preferable technical scheme, in the step (2), the reaction temperature is 65-90 ℃.

Preferably, in the step (5), the organic solvent used for the extraction includes at least one of toluene, ethylbenzene, xylene, cyclohexane, methylcyclohexane, chlorobenzene, dichlorobenzene, nitrobenzene, dichloromethane, chloroform, carbon tetrachloride, dichloroethane, butyl ether, and anisole.

In step (6), the organic solvent flashed off is recovered and recycled as an improved technical scheme.

Due to the adoption of the technical scheme, the invention has the beneficial effects that:

the invention adopts the catalyst with low price and easy obtainment, and the Lewis acid has the property of electron absorption, is beneficial to the replacement of hydroxyl on a pyrimidine ring by chlorine and promotes the rate of conversion from reaction to product, thereby obviously improving the reaction efficiency; the chlorine/liquid chlorine is used as a chlorinating agent to convert the 4, 6-dihydroxypyrimidine into the 4, 6-dichloropyrimidine, so that substances such as organic alkali and phosgene are avoided, the danger of the process is greatly reduced, a high-added-value product phosphorus oxychloride is produced as a byproduct, the complex and high-energy-consumption process of recycling and reusing the organic alkali is avoided, and the generation of phosphorus-containing wastewater is avoided; meanwhile, the prepared product has high yield and good quality, and is easy to realize continuous automatic industrial production.

When the phosphorus oxychloride is preferably used as the polar solvent, the phosphorus oxychloride is recovered together with the byproduct phosphorus oxychloride in the post-treatment process, so that the steps are saved, and the recovery rate is higher.

Detailed Description

The invention is further illustrated below with reference to specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.