阅读说明：本技术 一种4-氯乙酰乙酸乙酯的合成方法 (Synthesis method of 4-chloroacetoacetic acid ethyl ester ) 是由 张正颂 胡青阳 杨志健 王从春 于 2019-09-30 设计创作，主要内容包括：本发明公开了一种4-氯乙酰乙酸乙酯的合成方法,其特征在于：(1).双乙烯酮和二氯甲烷按体积比1:1~2组成混合液,从玻璃抽气管上方加入,速度5~15 mL/min,按乙烯酮：氯气摩尔比1:0.95~1从玻璃抽气管侧面入口加入,速度2~6 g/min；(2).直型真空接受管的侧面入口以2~7 mL/min的速度加无水乙醇,双乙烯酮：无水乙醇摩尔比1:1.2~1.3,蛇形冷凝管用水冷却,控制温度50~70℃,反应2~5h得到粗产品；(3).粗产物进行减压精馏,压力1~3 mmHg、塔顶温度45~60℃,即可得4-氯乙酰乙酸乙酯。本发明优点：1.此反应为连续反应,反应速度快,不会有大量危险物料累积,危险性小；2.设备成本较低,都是常规有机合成设备,无需贵重、特殊设备,便于复制,提高了生产效率。(The invention discloses a synthesis method of 4-chloroacetoacetic acid ethyl ester, which is characterized in that (1) diketene and dichloromethane form a mixed solution according to the volume ratio of 1:1 ~ 2, the mixed solution is added from the upper part of a glass exhaust tube at the speed of 5 ~ 15 mL/min, the mixed solution is added from the side inlet of the glass exhaust tube at the speed of 2 ~ 6 g/min according to the molar ratio of 1:0.95 ~ 1 of the diketene to chlorine, the mixed solution is added from the side inlet of the glass exhaust tube at the speed of 2 ~ 7 mL/min, the side inlet of a straight vacuum receiving tube is added with absolute ethyl alcohol at the speed of 2 ~ mL/min, the molar ratio of the diketene to the absolute ethyl alcohol is 1:1.2 ~ 1.3.3, a serpentine condenser tube is used for cooling water, the temperature is controlled to be 50 ~ 70 ℃, the reaction is carried out for 2 ~ 5h to obtain a crude product, 3) the crude product is subjected to reduced pressure rectification, the pressure is 1 ~ 3 mmHg, the overhead temperature is 45 ~ 60 at the top of the tower, the 4-chloroacetoacetic acid ethyl ester can be obtained, the invention has the advantages that 1, the reaction is continuous reaction, the reaction speed is fast.)

1. A synthetic method of 4-chloroacetoacetic acid ethyl ester is characterized by adopting the following devices: the device comprises a three-mouth flask, a snake-shaped condenser pipe, a straight vacuum receiving pipe and a glass exhaust pipe, wherein the snake-shaped condenser pipe, the straight vacuum receiving pipe and the glass exhaust pipe are sequentially and vertically connected above a middle inlet of the three-mouth flask;

the method comprises the following steps:

(1) adopting the device, mixing diketene and dichloromethane according to the volume ratio of 1:1 ~ 2 to form a mixed solution, adding the mixed solution from an inlet above the glass exhaust tube at the speed of 5 ~ 15 mL/min, and adding chlorine from an inlet at the side surface of the glass exhaust tube at the speed of 2 ~ 6 g/min according to the molar ratio of the diketene to the chlorine of 1:0.95 ~ 1;

adding absolute ethyl alcohol from a side inlet of a straight vacuum receiving pipe at the speed of 2 ~ 7 mL/min, controlling the molar ratio of diketene to the absolute ethyl alcohol to be 1:1.2 ~ 1.3.3, cooling by using a serpentine condenser pipe, controlling the reaction temperature to be 50 ~ 70 ℃, and obtaining a crude product after the reaction process is carried out for 2 ~ 5 h;

and (3) carrying out reduced pressure rectification on the crude product, and controlling the pressure to be 1 ~ 3 mmHg and the overhead temperature to be 45 ~ 60 ℃, thus obtaining the 4-chloroacetoacetic acid ethyl ester pure product with the content of more than or equal to 99.5 percent.

2. The method for synthesizing ethyl 4-chloroacetoacetate according to claim 1, wherein the method comprises the following steps: the length of the discharge pipe of the glass extraction pipe is 100-300 mm.

Technical Field

The invention belongs to the technical field of chemical production, and relates to a synthetic method of 4-chloroacetoacetic acid ethyl ester.

Background

4-chloroacetoacetic acid ethyl ester is an important raw material for synthesizing the ethyl dithiahydroxamate, but the raw material (4-chloroacetoacetic acid ethyl ester) used by the method is high in cost and cannot be widely applied; the prior production of 4-chloroacetoacetic acid ethyl ester has the following two problems, namely, the reaction needs to be carried out under the conditions of low temperature and low concentration due to too high activity of reactants (chlorine and diketene), and the yield is not easy to expand; secondly, the poor thermal stability and high boiling point of ethyl 4-chloroacetoacetate lead to easy decomposition during the product post-treatment (vacuum rectification).

Disclosure of Invention

The invention aims to solve the problems, and provides a synthesis method of 4-chloroacetoacetic acid ethyl ester, which optimizes the process flow and reduces the production cost.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a synthetic method of 4-chloroacetoacetic acid ethyl ester is characterized by adopting the following devices: the device comprises a three-mouth flask, a snake-shaped condenser pipe, a straight vacuum receiving pipe and a glass exhaust pipe, wherein the snake-shaped condenser pipe, the straight vacuum receiving pipe and the glass exhaust pipe are sequentially and vertically connected above a middle inlet of the three-mouth flask;

the method comprises the following steps:

(1) adopting the device, mixing diketene and dichloromethane according to the volume ratio of 1:1 ~ 2 to form a mixed solution, adding the mixed solution from an inlet above the glass exhaust tube at the speed of 5 ~ 15 mL/min, and adding chlorine from an inlet at the side surface of the glass exhaust tube at the mol ratio of 1:0.95 ~ 1 of the diketene to the chlorine at the speed of 2 ~ 6 g/min;

(2) adding absolute ethyl alcohol from a side inlet of a straight vacuum receiving pipe at the speed of 2 ~ 7 mL/min, controlling the molar ratio of the diketene to the absolute ethyl alcohol to be 1:1.2 ~ 1.3.3, introducing condensed water (20-30 ℃) from a water inlet at the lower part of a serpentine condenser pipe, controlling the reaction temperature to be 50 ~ 70 ℃, and carrying out the reaction process for 2 ~ 5h to obtain a crude product (brown to wine red liquid);

(3) rectifying the crude product under reduced pressure (glass spring packed column), controlling the pressure at 1 ~ 3 mmHg and the overhead temperature at 45 ~ 60 ℃ to obtain a pure 4-chloroacetoacetic acid ethyl ester product (the content is more than or equal to 99.5 percent);

further, the length of the discharge pipe of the glass extraction pipe is 100-300 mm.

The diketene is an unstable and easily polymerizable compound, and tends to have lower yield under severe reaction conditions, and the reduction of the reaction temperature and the reduction of the reaction time are beneficial to the reduction of side reactions. In the invention, a glass exhaust tube (a common glass instrument for generating vacuum by using a Venturi effect, wherein liquid and gas are violently collided and mixed) is adopted to realize the reaction of diketene and chlorine, dichloromethane is used as a solvent, and meanwhile, part of heat can be taken away by using the gasification of dichloromethane, so that local overheating is avoided. Pumping by using a water jet pump (preferably a circulating water vacuum pump) to ensure that the flask is at a negative pressure, wherein the negative pressure can reduce the boiling point of dichloromethane, so that the reaction process is maintained at a lower temperature; the water jet pump is used because the gas to be pumped out contains volatile hydrogen chloride gas and methylene dichloride steam, the water jet pump can take the hydrogen chloride and the methylene dichloride away by water, the methylene dichloride is recovered by separating, and hydrochloric acid can be produced as a byproduct after the hydrogen chloride is dissolved into the water, and other types of vacuum pumps, such as a piston pump, an oil ring pump and the like, are not suitable for working under the conditions of strong acid and organic matters.

The invention has the advantages that: 1. the reaction is continuous, the reaction speed is high, a large amount of dangerous materials (chlorine and diketene) cannot be accumulated, and the danger is low; 2. the equipment cost is low, the equipment is conventional organic synthesis equipment, expensive and special equipment is not needed, the duplication is convenient, and the production efficiency is improved.

Drawings

FIG. 1 is a schematic view of an apparatus for synthesizing ethyl 4-chloroacetoacetate.

Detailed Description

With reference to fig. 1, a synthesis apparatus for ethyl 4-chloroacetoacetate: three-neck flask (magneton) including 5000 mL, snakelike condenser pipe (the snake pipe part is 250 mm), straight type vacuum receiver tube, glass exhaust tube (discharge tube length is 200 mm), the snakelike condenser pipe is connected perpendicularly in proper order above the middle entry of three-neck flask, straight type vacuum receiver tube, the glass exhaust tube, lean on rubber buffer sealing connection between straight type vacuum receiver tube and the glass exhaust tube, diketene, chlorine, absolute ethyl alcohol all use the polytetrafluoroethylene tube of external diameter eighth inch to carry, polytetrafluoroethylene tube and glass exhaust tube junction use multilayer raw material area winding sealed.