阅读说明：本技术 一种二氯丙醇的合成方法 (Method for synthesizing dichloropropanol ) 是由 周响 程终发 王燕平 于 2020-12-10 设计创作，主要内容包括：本发明提供了一种用甘油和氯化氢为原料,分子筛和硅胶为除水剂,经体系内循环,合成二氯丙醇的方法。本发明直接利用甘油和氯化氢反应,同时除反应水,合成二氯丙醇,整个过程只存在有机相和气相,避免了三元共沸物的产生和处理操作,优化流程,降低生产成本。本发明在循环除水的同时,促进氯化氢的醇羟基取代的反应平衡,提高反应速率和转化率,缩短反应周期,降低成本,同时制备纯度＞99%的二氯丙醇产品。本发明使用分子筛-硅胶体系物理除水,经洗涤烘干后即可循环使用,操作简单方便,且洗涤液可作母液回用,无三废产生,绿色环保,有利于工业化生产。(The invention provides a method for synthesizing dichloropropanol by using glycerol and hydrogen chloride as raw materials and using a molecular sieve and silica gel as water removal agents through system internal circulation. The invention directly utilizes the reaction of glycerol and hydrogen chloride, removes reaction water at the same time, synthesizes the dichloropropanol, only has an organic phase and a gas phase in the whole process, avoids the generation and treatment operation of ternary azeotrope, optimizes the process and reduces the production cost. The method promotes the reaction balance of the substitution of the alcoholic hydroxyl group of the hydrogen chloride while circularly removing water, improves the reaction rate and the conversion rate, shortens the reaction period, reduces the cost, and simultaneously prepares the dichloropropanol product with the purity of more than 99 percent. The method uses a molecular sieve-silica gel system to physically remove water, can be recycled after washing and drying, is simple and convenient to operate, can be used as mother liquor for recycling, does not generate three wastes, is green and environment-friendly, and is beneficial to industrial production.)

1. The method for synthesizing dichloropropanol is characterized by comprising the following steps of:

1) adding the metered glycerol into a reaction container, and enabling the glycerol to flow through a water removal device through the reaction container and then return to the reaction container to form internal circulation;

2) starting stirring and rapidly heating to 80-100 ℃, and simultaneously introducing hydrogen chloride gas into the reaction kettle to perform monochloro substitution reaction for 2-4h;

3) heating the system to 110-120 ℃, continuously introducing hydrogen chloride gas to carry out a dichloro substitution reaction, and stopping the reaction after the reaction is carried out for 5-7 hours;

4) collecting all reaction liquid in the circulating system, and rectifying the reaction liquid to obtain the dichloropropanol product and the mother liquor.

2. The method according to claim 1, wherein the molar ratio of hydrogen chloride to glycerol in step 2) is 1.0-1.5: 1; in the step 3), the molar ratio of the hydrogen chloride dosage to the glycerol dosage is 1.0-2.0: 1.

3. the method of claim 1 wherein the water removal unit is a molecular sieve-silica gel column.

4. The method according to claim 3, wherein the molecular sieve-silica gel column group is formed by connecting multiple tubes in parallel, the diameter of each single tube is 3-5 cm, the length of each single tube is 1-2 m, and the molecular sieve and the silica gel are filled in the single tubes in a filling volume ratio of 10-30: 1.

5. The method according to claim 4, wherein the molecular sieve is an aluminosilicate molecular sieve A3-A4, which is a water absorption main body, and the silica gel is allochroic silica gel.

6. The method according to claim 5, wherein the plurality of molecular sieve-silica gel column groups are connected in parallel, when in use, the reaction liquid only flows through one of the molecular sieve-silica gel column groups, whether the molecular sieve-silica gel column group is inactivated is judged according to the color change of silica gel, and other molecular sieve-silica gel column groups connected in parallel are replaced in time.

7. The method according to claim 6, wherein the molecular sieve-silica gel column group is deactivated, and repeatedly washed with a small amount of isopropanol, the molecular sieve and the silica gel in the group are dried and reused, the isopropanol in the washing liquid containing the isopropanol is distilled off and reused, and the residual liquid is used as mother liquor to enter a reaction system.

8. The method according to claim 1, wherein the flow rate per 10 molecular sieve columns in the internal circulation process of the reaction solution is 5-10% of the flow rate of the hydrogen chloride introduced during the monochloro-substitution reaction.

9. The method of claim 1, wherein the reaction system uses nitrogen as a shielding gas.

10. The method of claim 1, wherein water is added into the reaction kettle before introducing the hydrogen chloride gas, wherein the water is high-purity water, and the amount of the water is 4-5vt% of the hydrogen chloride.

Technical Field

The invention relates to the technical field of fine chemicals, in particular to a method for synthesizing dichloropropanol.

Background

Epichlorohydrin, namely 3-chloro-1, 2-epoxypropane, is an important organic chemical raw material and a synthetic intermediate, can be used as a solvent for cellulose ester, resin and cellulose ether, is also a raw material for producing surfactants, medicines, pesticides, coatings, adhesives, ion exchange resins, plasticizers, glycerol derivatives and glycidyl derivatives, and is widely applied to the industries of chemical industry, light industry, medicines, electronics and the like.

The prior production method of epoxy chloropropane mainly comprises 3 methods: propylene high-temperature chlorination process using propylene as a raw material, propylene acetate process, and glycerin chlorination process using glycerin as a raw material. The propylene high-temperature chlorination method and the acetate propylene ester method which take propylene as raw materials face the technical problem of catalysts, the yield is less than 90 percent, the three wastes treatment cost is high, the industrial scale is small, the byproducts are more, the environmental pollution is serious, and meanwhile, the further development of the downstream product epichlorohydrin is seriously limited because the main raw materials of propylene and chlorine are insufficient. With the progress of social development, a method for synthesizing dichloropropanol by using a glycerol method and further synthesizing epichlorohydrin gradually becomes a mainstream.

The technical research of synthesizing dichloropropanol by glycerol at home and abroad also obtains certain achievements.

Patent CN101570471A discloses that glycerol and organic acid are catalyzed by using strong acid cation exchange resin and active carbon, silica gel, alumina or their mixture loaded with p-toluenesulfonic acid to perform esterification reaction to generate organic acid glyceride, and dichloropropanol is prepared by chlorination and hydrochlorination.

In patent CN101704722A, dicarboxylic acid-rare earth chloride trisodium cerium chloride and lanthanum trichloride are used as composite catalysts to catalyze glycerin and hydrogen chloride gas to generate dichloropropanol, organic solvent is used to bring out water generated in the reaction system, and benzene and toluene water carrying agents are used, which not only increases production cost, but also easily causes adverse effects on the environment.

Patent CN106466615A discloses a catalytic glycerol chlorination method for synthesizing dichloropropanol by using a catalyst prepared by mixing modified attapulgite, ethyl orthosilicate, absolute ethyl alcohol, phosphotungstic acid and deionized water according to a certain mass ratio, aging, drying and roasting at high temperature. The method has complex catalyst preparation process and is not easy to realize large-scale industrial production.

Patent CN102040479 discloses a process for preparing dichloropropanol by autocatalytic reaction of glycerol and hydrogen chloride, which needs to be completed under high temperature and high pressure conditions, and the conversion rate of glycerol is unstable.

Patent CN108863718A (the unit of this application) discloses a method for catalyzing glycerol and hydrogen chloride gas to generate dichloropropanol by using organic carboxylic acid/inorganic lewis acid as a composite catalyst.

The method adopts a strong acid catalyst, glycerin chloride, azeotropic dehydration of generated water and dichloropropanol, or separation by using a chemical reagent on the basis of dichloropropanol hydrochloric acid azeotrope, thereby improving the cost of later dichloropropanol purification. In addition, the synthesis method does not consider isomerides, and 1, 3-dichloro-2-propanol and 2, 3-dichloro-1-propanol coexist in the product.

Disclosure of Invention

Aiming at the problems of difficult water removal and single product in the prior art, the invention provides a simple and efficient method for synthesizing dichloropropanol.

A method for synthesizing dichloropropanol comprises the following steps:

1) after nitrogen is introduced into the reaction system to exhaust air, a certain amount of glycerol is added into a reaction container, and the reaction container and the molecular sieve-silica gel column group form internal circulation;

2) starting stirring and rapidly heating to 80-100 ℃, simultaneously introducing hydrogen chloride gas at a certain flow rate to perform monochloro substitution reaction, and continuously circulating the reaction liquid into a reaction container through a molecular sieve column for 2-4 hours;

3) and (3) heating the system to 110-120 ℃, continuously introducing hydrogen chloride gas at a certain flow rate to carry out a dichloro substitution reaction, continuously circulating the reaction liquid, and stopping the reaction after 5-7 hours.

Rectifying the reaction liquid to obtain dichloropropanol and mother liquid, recycling the mother liquid in a reaction kettle, drying the hydrogen chloride for recycling, and processing the molecular sieve and the silica gel for recycling.

Further, in the step 2), during the monochloro substitution reaction, the molar ratio of hydrogen chloride to glycerol is 1.0-1.5: 1, the molar ratio of hydrogen chloride to glycerol during the dichloro substitution reaction in the step 3) is 1.0-2: 1.

further, the hydrogen chloride flow rates during the monochloro substitution reaction and the dichloro reaction are determined by the amount of hydrogen chloride used in each period and the respective reaction time.

Furthermore, in the internal circulation process of the reaction liquid, the flow rate corresponding to each 10 molecular sieve columns is 5-10% of the flow rate of the hydrogen chloride introduced in the monochloro substitution reaction period.

Furthermore, the molecular sieve-silica gel column group is formed by connecting a plurality of pipes in parallel, the diameter of a single pipe is 3-5 cm, the length of the single pipe is 1-2 m, the molecular sieve and the silica gel are filled in the molecular sieve-silica gel column group, and the filling volume ratio of the molecular sieve-silica gel column group to the silica gel column group is (10-30): 1, preferably (15-20): 1.

Furthermore, the filler molecular sieve is an aluminosilicate molecular sieve of A3-A4 and is a water absorption main body, and the filler silica gel is allochroic silica gel and mainly plays a role of an indicator.

Furthermore, a plurality of the molecular sieve-silica gel column groups are connected in parallel, when the device is used, reaction liquid only flows through one of the molecular sieve-silica gel column groups, whether the molecular sieve-silica gel column group is inactivated or not is judged according to the color change of silica gel, and other molecular sieve-silica gel column groups connected in parallel are replaced in time.

Further, after the inactivated molecular sieve-silica gel column group is repeatedly washed by a small amount of isopropanol, the molecular sieve and the silica gel in the inactivated molecular sieve-silica gel column group are dried and reused, the isopropanol is distilled from the washing liquid containing the isopropanol and reused, and the residual liquid is used as mother liquor to enter a reaction system.

Further, a small amount of water (4-5 vt% of the hydrogen chloride gas) was introduced before the introduction of the hydrogen chloride gas. Water acts as a starter, driving the reaction to start and circulate.

The invention does not adopt a strong acid catalyst, glycerin and hydrogen chloride directly react, and in order to prevent a final dichloroethanol-water-hydrogen chloride negative ternary azeotropic system from appearing, the invention adopts a molecular sieve-silica gel to remove water.

More, in the actual production process, the reaction cannot occur in a non-strong acid environment or without a catalyst, the reaction generates water, and the excessive water prevents the equilibrium reaction from being complete. Therefore, the inventor adds a small amount of water in the reaction kettle as a starter, the hydrogen chloride is ionized, and the water generated in the reaction is circulated along with the reaction liquid and absorbed by the molecular sieve-silica gel. Thus only a small amount of water remains in the entire circulation system to promote the reaction (water is mainly present in the reaction vessel). After the reaction is finished, no water is generated, and all water (generated water + water added as a starter) is circularly absorbed by the molecular sieve-silica gel. The invention finally obtains the hydrogen chloride-dichloropropanol binary system, which is easier to rectify and purify.

The invention has the beneficial effects that:

the method directly uses the glycerol to react with the hydrogen chloride, removes water during the reaction process, and only remains organic phase and hydrogen chloride gas, thereby avoiding the generation of ternary azeotrope, optimizing the reaction flow and reducing the production cost.

The invention promotes the forward movement of the reaction balance of the substitution of the alcoholic hydroxyl of the hydrogen chloride by circularly removing water in the reaction liquid, saves the reaction time, improves the conversion rate and can directly prepare the dichloropropanol with the purity of more than 99 percent.

The molecular sieve-silica gel water removing agent is used for washing and drying, and can be recycled, the washing liquid can be used as mother liquid for recycling, the treatment method is simple and easy to operate, the production cost is low, the three wastes are not generated in the whole reaction process, and the method is green and environment-friendly and is beneficial to industrial production.

Detailed Description

The present invention is described in detail below by way of examples, which are intended to be illustrative only and not to be construed as limiting the scope of the invention, and one skilled in the art will be able to make variations within the scope of the invention based on the disclosure herein, in reagents, catalysts and reaction process conditions. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

The specification of part of raw materials and equipment used in the examples:

the glycerol is of industrial grade, and the purity is 95.4%; the purity of the nitrogen and the chlorine is 99.9 percent.

The reaction kettle is a 1 cubic enamel reaction kettle; 20 molecular sieve columns with the diameter of 3cm and the length of 1.2m are connected in parallel in the water removal device, and the volume ratio of the internal packing molecular sieve to the silica gel is 20: 1.

Example 1

The method comprises the following steps: heating nitrogen to 75 +/-5 ℃ by an air heating device, introducing the nitrogen into a reaction system at the flow rate of 100L/min, discharging air and water, adding 630kg of glycerol into a reaction kettle, starting stirring, heating to 95 +/-5 ℃, simultaneously starting internal circulation of the reaction kettle and a water removal device, and pumping reaction liquid into the water removal device from the reaction kettle at the flow rate of 50L/min for internal circulation.

Step two: introducing hydrogen chloride gas from the bottom of the reaction kettle liquid through a compression buffer tank at a flow rate of 1000L/min, wherein the total volume is 185 cubic, the unreacted hydrogen chloride is circularly reacted in the system, after 3.5 hours, the hydrogen chloride gas in the compression buffer tank is nearly dried, and the monochloro reaction is finished to generate the intermediate chloropropanol.

Step three: heating the system to 115 +/-5 ℃, continuously introducing hydrogen chloride gas from the bottom of the reaction kettle liquid through a compression buffer tank according to the flow of 800L/min, taking up to 240 cubic meters, circularly reacting unreacted hydrogen chloride in the system, and after 6.2 hours, leaving a small amount of gas in the compression buffer tank, completing the dichlorinated reaction to generate a product dichloropropanol mixed solution. Rectifying the mixed solution to obtain 785.9kg of dichloropropanol, and adding the residual mother liquor into the raw materials for recycling.

The appearance of the obtained dichloropropanol product is colorless transparent liquid, and the detection shows that the primary conversion rate (calculated by glycerol) of the dichloropropanol is 94.2%, the primary yield (calculated by glycerol) is 92.99%, the purity is 99.6% and the chroma (Hazen) is 16.

The treatment method of the molecular sieve comprises the following steps: and after the silica gel in the molecular sieve column is completely discolored, switching other standby dewatering devices through a valve, circularly flushing the dewatering devices for 30min by using 150kg of isopropanol according to the flow of 50L/min, rectifying and separating the obtained flushing liquid to obtain 149.9kg of isopropanol, 20.7kg of dichloropropanol and 1.6kg of mother liquor, and disassembling and drying the flushed molecular sieve column for standby.

Example 2

The method comprises the following steps: heating nitrogen to 75 +/-5 ℃ by an air heating device, introducing the nitrogen into a reaction system at the flow rate of 100L/min, discharging air and water, adding 580kg of glycerol into a reaction kettle, starting stirring, heating to 90 +/-5 ℃, simultaneously starting internal circulation of the reaction kettle and a water removal device, and pumping reaction liquid into the water removal device from the reaction kettle at the flow rate of 50L/min for internal circulation.

Step two: introducing hydrogen chloride gas from the bottom of the reaction kettle liquid through a compression buffer tank at the flow rate of 1000L/min, totaling 160 cubic, circularly reacting unreacted hydrogen chloride in the system, and after 3 hours, nearly drying the hydrogen chloride gas in the compression buffer tank to finish monochloro reaction to generate an intermediate chloropropanol.

Step three: heating the system to 110 +/-5 ℃, continuously introducing hydrogen chloride gas from the bottom of the reaction kettle liquid through a compression buffer tank according to the flow of 800L/min, wherein the total volume is 200 cubic, unreacted hydrogen chloride circularly reacts in the system, and after 5.4 hours, a small amount of gas in the compression buffer tank is left, and the dichlorohydrin reaction is finished to generate a dichlorohydrin mixed solution. The mixed solution is rectified to obtain 725.2kg of dichloropropanol, and the residual mother liquor is added into the raw materials for recycling.

The appearance of the obtained dichloropropanol product is colorless transparent liquid, and the detection shows that the primary conversion rate (calculated by glycerol) of the dichloropropanol is 94.6%, the primary yield (calculated by glycerol) is 93.11%, the purity is 99.5% and the chroma (Hazen) is 15.

Comparative example 1 (Synthesis route of dichloropropanol with adipic acid as catalyst and dichloromethane as extractant)

Adding 400kg of glycerol and 50kg of oxalic acid into a reaction kettle, starting stirring, heating to 75 +/-5 ℃, starting introducing hydrogen chloride gas at the flow rate of 1000L/min, drying unreacted hydrogen chloride gas for recycling, continuously heating to 115 +/-5 ℃ in the reaction kettle, reacting for 8 hours to obtain 276kg of ternary azeotrope and 432kg of reaction liquid in the kettle.

Carrying out vacuum rectification on the reaction liquid to obtain 415kg of dichloropropanol and 17kg of mother liquid, wherein the mother liquid is recycled; and transferring the ternary azeotrope into an extraction tower, simultaneously adding 400kg of extracting agent dichloromethane, extracting, layering and rectifying to obtain 95kg of dichloropropanol, 175kg of hydrochloric acid and 401kg of dichloromethane, and sleeving the separated dichloromethane for extraction.

The appearance of the obtained dichloropropanol product is colorless transparent liquid, and the detection shows that the primary conversion rate (calculated by glycerol) of the dichloropropanol is 91.1%, the primary yield (calculated by glycerol) is 74.1%, the purity is 99.5% and the chroma (Hazen) is 16.

Comparative example 2 (too fast circulation flow rate of reaction solution, high water content of system, ternary azeotrope formation, unable to directly get qualified product)

The method comprises the following steps: heating nitrogen to 75 +/-5 ℃ by an air heating device, introducing the nitrogen into a reaction system according to the flow of 100L/min, discharging air and water, adding 630kg of glycerol into a reaction kettle, starting stirring, heating to 95 +/-5 ℃, simultaneously starting internal circulation of the reaction kettle and a water removal device, and pumping reaction liquid into the water removal device from the reaction kettle according to the flow of 500L/min for internal circulation.

Step two: introducing hydrogen chloride gas from the bottom of the reaction kettle liquid through a compression buffer tank at a flow rate of 1000L/min, wherein the total volume is 185 cubic, the unreacted hydrogen chloride is circularly reacted in the system, after 3.5 hours, the hydrogen chloride gas in the compression buffer tank is nearly dried, and the monochloro reaction is finished to generate the intermediate chloropropanol.

Step three: heating the system to 115 +/-5 ℃, continuously introducing hydrogen chloride gas from the bottom of the reaction kettle liquid through a compression buffer tank according to the flow of 800L/min, wherein the total volume is 240 cubic, unreacted hydrogen chloride circularly reacts in the system, after 6.2 hours, a small amount of gas remains in the compression buffer tank, the dichloro reaction is finished, and the generated product is the hydrochloric acid aqueous solution (ternary azeotrope) of dichloropropanol, wherein the total volume is 963.6 kg.

Through detection, the obtained ternary azeotrope has the dichloropropanol content of 81.56%, the water content of 14.74% and the hydrogen chloride content of 3.65. The ternary azeotrope is subjected to a complicated separation treatment to obtain high-purity dichloropropanol.

Comparative example 3

The circulating flow rate of the reaction liquid is slowed down to 10L/min, other steps are the same as those in the example 1, water is completely removed by the silica gel-molecular sieve in the reaction process, no water exists in the whole system, the reaction is interrupted, only the reference is used for comparison, and the subsequent purity test of the product cannot be carried out.