A kind of continuous production technology of 3,6-dichlorosalicylic acidTechnical field
The present invention relates to a kind of production technology for synthesizing Mediben key intermediate, it is more particularly related to a kind of 3, the continuous production technology of 6-dichlorosalicylic acid, belong to the intermediate technical field of synthetic herbicide Mediben.
Background technology
Generally synthesis 3, the technique of 6-dichlorosalicylic acid uses still reaction, and reaction unit is autoclave, the most in the basic conditions, 2,5-chlorophenesic acids form phenates, and then solvent bank water is to aqueous below the 50ppm of system, proceed to autoclave again, add potassium carbonate catalyst, be passed through CO2Carry out carboxylation reaction, generate 3,6-dichlorosalicylic acid salt, then after reactant mixture being added water stratification, aqueous phase product adds acid and is acidified, vapor distillation separation and recovery unreacted 2,5-chlorophenesic acid, sucking filtration is dried and is then obtained pure 3,6-dichlorosalicylic acid solid.Being solvent high pressure carboxylation method, klobe-schitt reacts.In this technique, below carboxylation reaction material system water content 50ppm, technological requirement is high, and difficulty is big；The carboxylation reaction time is long, and coking is serious, and product yield is low, is only about 45%；High-temperature high-pressure apparatus and relevant auxiliary facility investment demand are high.It addition, prior art cannot realize 3, the continuous prodution of 6-dichlorosalicylic acid.
State Intellectual Property Office discloses Publication No. CN103012124A in 2013.4.3, the invention of entitled " 3; preparation method of the chloro-2 hydroxybenzoic acid of 6-bis-", this disclosure of the invention a kind of 3, the preparation method of the chloro-2 hydroxybenzoic acid of 6-bis-, comprise the following steps successively: 1) 2,5-chlorophenesic acid becomes salt；2) carboxylation: by 2,5-chlorophenesic acid saline solution is transferred in autoclave, adds co-catalyst, then passes to CO2 and carry out high pressure carboxylation reaction, must be containing 3, the product of 6-bis-chloro-2 hydroxybenzoic acid salt；Co-catalyst is made up of potassium carbonate and activated carbon；3) refined: by step 2) gained containing 3, after the product of 6-bis-chloro-2 hydroxybenzoic acid salt is cooled to room temperature, add aqueous slkali, regulate pH to 11 ~ 13, stir, activated carbon is recovered by filtration, phase of fetching water after filtrate layering；Adding acid solution in aqueous phase, regulate pH to 1 ~ 3, reclaim 2 through steam distillation, after 5-chlorophenesic acid, crystallisation by cooling, sucking filtration are dried, and obtain 3, the chloro-2 hydroxybenzoic acid of 6-bis-.Utilizing potassium carbonate and activated carbon co-catalyst in this method, reduce the consumption of potassium carbonate, reduce cost, but the response time is long, once through yield is low, and simply about 46%；
State Intellectual Property Office discloses Publication No. CN104086393A in 2014.10.8, the invention of entitled " the 3 of a kind of improvement; the preparation method of 6-dichlorosalicylic acid ", this disclosure of the invention 3 of a kind of improvement, the preparation method of 6-dichlorosalicylic acid, step is: by 2, and 5-chlorophenesic acid and alkaline reaction are subsequently adding organic solvent decompression dehydration；Add potassium carbonate, dehydrant and stabilizer after dehydration, react 30-60 minute at 130-140 DEG C；Material is added autoclave, is warming up to 130-140 DEG C, then pass to CO2 and carry out high pressure carboxylation reaction；Carry out post processing after reaction, obtain 3,6-dichlorosalicylic acid.The present invention is starvation before dehydration, carboxylation, avoid the oxygen oxidation to product, dehydrant and stabilizer is added before carboxylation, the hydrogen radical cation generated when eliminating the water in system and carboxylation further, maintain system stability, ensure that yield and be substantially improved product appearance, reducing the consumption of potassium carbonate, simplify last handling process.Additionally, the method is relatively low to the change of equipment, facilitating current manufacturing enterprise to implement to improve, can comparatively fast take effect benefit.In the method, the carboxylation reaction time is long, and reactant selectivity is low by about 94%, and complex process, and production cost is high.
State Intellectual Property Office discloses Publication No. CN102942474A in 2013.2.27, the invention of entitled " synthesis technique of a kind of herbicide dicamba ", this disclosure of the invention preparation method of a kind of herbicide dicamba, including: (1) liquid potassium hydroxide and 2,5-chlorophenesic acid obtains 2 with the molar ratio reaction of 0.95:1 ~ 1:1,5-chlorophenesic acid potassium；(2) the 2 of step (1) gained, 5-chlorophenesic acid potassium, in the presence of Anhydrous potassium carbonate and catalyst, reacts production 3,6-dichlorosalicylic acid with CO2；The pressure controlling CO2 is 4 ~ 6MPa, and reaction temperature 100 ~ 160 DEG C, Anhydrous potassium carbonate and 2, the mol ratio of 5-chlorophenesic acid potassium is 1 ~ 2:1；(3) in the basic conditions, at a temperature of 70 ~ 100 DEG C, by step (2) gained 3,6-dichlorosalicylic acid and chloromethanes press the mol ratio of 1:1 ~ 3.5 through calandria type fixed bed reactor, react under the effect of catalyst, 3 are obtained again through saponification, acidifying, 6-bis-chloro-2-methoxysalicylic acid, i.e. Mediben.The technological reaction yield of the present invention is high, reaction condition is simple, good product quality, the three wastes are few, energy consumption is low.
There is water content and require harshness in above-mentioned technique of the prior art, tar is many, and equipment investment cost is high, production efficiency and the low problem of product yield, and cannot continuous prodution.
Summary of the invention
Present invention seek to address that existing 3, during 6-dichlorosalicylic acid produces, reaction system water content requires harshness, tar is many, and equipment investment cost is high, production efficiency and the low problem of product yield, there is provided a kind of 3, the continuous production technology of 6-dichlorosalicylic acid, it is possible to reduce the rigors to reaction system water content, reduces coking, reduce equipment investment cost, and high efficiency, continuous prodution.
In order to realize foregoing invention purpose, its concrete technical scheme is as follows:
A kind of 3, the continuous production technology of 6-dichlorosalicylic acid, it is characterised in that: comprise the following steps that:
A, in batching kettle by 2, the xylene solution of 5-chlorophenesic acid potassium, Anhydrous potassium carbonate powder, dispersant stirring and evenly mixing, obtain slip；
B, the slip in step A is pumped into carbon dioxide absorption still by dosing pump, open carbon dioxide air source, carry out carbon dioxide absorption, then slip pumps into reaction under high pressure section through dosing pump and reacts, and described reaction under high pressure section includes reacting pipe and the blender being arranged on reacting pipe；
C, the slip reacted through reaction under high pressure section, enter pressure release discharging section, described pressure release discharging section includes relief valve, surge tank, condenser, acidifying still and the filter-pressing device being sequentially connected with, and slip enters surge tank after relief valve pressure release, then cools down through condenser, acidifying still acidifying, filter pressing, washing obtains 3,6-dichlorosalicylic acid wet product, finally it is dried to obtain 3,6-dichlorosalicylic acid product.
In step, the preparation technology of described 2,5-chlorophenesic acid potassium is the present invention: under nitrogen protection; by 2,5-chlorophenesic acid is dissolved in dimethylbenzene, prepares 2; the xylene solution of 5-chlorophenesic acid, is then under agitation added dropwise to 2, in the xylene solution of 5-chlorophenesic acid by potassium hydroxide aqueous solution; drip complete, be heated to boiling, distillation; when moisture reaches below 2000ppm in the dimethylbenzene that mensuration distillates, stop distillation, be then cooled to less than 100 DEG C; obtain 2,5-chlorophenesic acid potassium liquid.
The present invention in step, is passed through carbon dioxide after dispensing and protects in described batching kettle.
In step, described 2,5-chlorophenesic acid potassium, dimethylbenzene, Anhydrous potassium carbonate powder, the mass ratio of dispersant are 1:4-6:0.5-1.5:0.01-0.2 to the present invention.
Above-mentioned dispersant is one or more mixture in paraffin, sulfonate, higher fatty acids, Polyethylene Glycol, carboxymethyl cellulose.
Above-mentioned paraffin, sulfonate, higher fatty acids, Polyethylene Glycol, the mass ratio of carboxymethyl cellulose are 0.02-0.1:0.01-0.05:0.02-0.1:0.01-0.05:0.01-0.05.
Above-mentioned higher fatty acids is lauric acid, stearic acid or stearic sulfonate.
In stepb, described slip Liquid level in described carbon dioxide absorption still is at submergence stirrer paddle, and the 30-80% that described slip volume is described carbon dioxide absorption still volume for the present invention.
The present invention in stepb, described in carry out carbon dioxide absorb time, control kettle temperature 35-170 DEG C, pressure 3.5-7.8MPa, soak time 0.5-50s.
The present invention in stepb, when described reaction under high pressure section is reacted, keeps temperature of reaction system 120-170 DEG C, and pressure 5.0-7.8MPa, the response time is 1.5-6 hour.
The present invention is in step C, and described condenser is cooled to 40-100 DEG C.
The present invention is in step C, and the acidifying of described acidifying still, for keeping temperature 40-100 DEG C, stirs lower hydrochloric acid, regulates pH to 1-3, is cooled to 0-20 DEG C.
Batching kettle of the present invention is connected with described carbon dioxide absorption still by dosing pump, described carbon dioxide absorption still is connected with described reaction under high pressure section by dosing pump, described reaction under high pressure section is connected with described surge tank further through described relief valve, described surge tank one end with described condenser again is connected, the other end of described condenser connects described acidifying still, and described acidifying still is connected with described filter-pressing device again.
Carbon dioxide absorption still of the present invention forms a unit with described reaction under high pressure section, and this unit is two or more, is connected in series with each other.
Carbon dioxide absorption still of the present invention is two or more, is connected in series with each other.
Reaction under high pressure section of the present invention is two or more, is connected in series with each other.
Connected by dosing pump between above-mentioned reaction under high pressure section.
Absorption kettle heater, absorption kettle chiller, level display device, attemperating unit, pressure control device and pressure-display device it is provided with on carbon dioxide absorption still of the present invention.
Blender of the present invention is static mixer.
Blender of the present invention is two or more.
It is provided with heater in reaction under high pressure section of the present invention.
The Advantageous Effects that the present invention brings:
1, the present invention solves existing 3, during 6-dichlorosalicylic acid produces, reaction system water content requires harshness, tar is many, and equipment investment cost is high, production efficiency and the low problem of product yield, there is provided a kind of 3, the continuous production technology of 6-dichlorosalicylic acid, it is possible to reduce the rigors to reaction system water content, reduces coking, reduce equipment investment cost, and high efficiency, continuous prodution.Present invention process reduces the rigors to reaction system water content, as long as moisture reaches below 2000ppm and just can meet reaction requirement, once through yield is high, and selectivity is high, and coking is few.Use present invention process yield more than 55%, selectivity more than 96%.
2, the present invention uses continuous reacting device, greatly reduces reaction mass and turns material and get the raw materials ready the time, gas displacement process, remove reactant last handling process, reduce whole operation process, reduce a large amount of high-temperature high-pressure reaction kettle, reduce place capacity, reduce equipment investment cost.
4, the continuous reaction of the present invention uses specific continuous reaction system, big compared to the one-pot reaction scale of construction, liter gentle reactant of getting the raw materials ready is lowered the temperature, gas displacement, turn the times such as material more defect, using continuous reaction system to carry out continuous reaction, these operate spent time or cancellations or significantly reduce.
5, specific dispersant of the present invention and the addition of special ratios, promotes that reaction is carried out to primary response, reduces the generation of side reaction, improve product selectivity.Dispersant can make catalyst and generation product be uniformly dispersed in system simultaneously, reduces coking on attachment wall.Assemble it addition, dispersant can reduce catalyst, improve its usefulness, be substantially reduced the requirement to speed of agitator, the content requirement of moisture in reaction system is reduced.
6, the continuous reaction process of the present invention, can reduce substantial amounts of high temperature and high pressure kettle, greatly reduces equipment investment expense；Reduce floor space, save space；It is easily achieved industrial automatic control, reduces artificial input.
7, the present invention specific dispersant package dispersive property is good, makes catalyst and generation product be uniformly dispersed in system, reduces coking on attachment wall；Reduce catalyst to assemble, improve its usefulness；It is substantially reduced in this technique solid-liquid-gas three phase reactant system mixing requirement, selects static mixer just to can reach desired product yield and selectivity；Moisture in adsorption reaction system, reduces moisture requirement.And then dispersive agent ratio scope limit make the preferable dispersibility of reaction system, coking is few, and cost is excellent.
Accompanying drawing explanation
The structural representation of the system that Fig. 1 is used by present invention process.
The carbon dioxide absorption still of the system that Fig. 2 is used by present invention process and reaction under high pressure segment unit are structural representation when two.
Structural representation when two carbon dioxide absorption stills of the existence of the system that Fig. 3 is used by this present invention process and two reaction under high pressure section (one of them reaction under high pressure section arrange two blenders).
Reference: 1 be batching kettle, 2 be carbon dioxide absorption still, 3 be reacting pipe, 4 be blender, 5 be relief valve, 6 be surge tank, 7 be condenser, 8 be acidifying still, 9 be filter-pressing device, 10 for heater.
Detailed description of the invention
Embodiment 1
A kind of 3, the continuous production technology of 6-dichlorosalicylic acid, comprise the following steps that:
A, in batching kettle by 2, the xylene solution of 5-chlorophenesic acid potassium, Anhydrous potassium carbonate powder, dispersant stirring and evenly mixing, obtain slip；
B, the slip in step A is pumped into carbon dioxide absorption still by dosing pump, open carbon dioxide air source, carry out carbon dioxide absorption, then slip pumps into reaction under high pressure section through dosing pump and reacts, and described reaction under high pressure section includes reacting pipe and the blender being arranged on reacting pipe；
C, the slip reacted through reaction under high pressure section, enter pressure release discharging section, described pressure release discharging section includes relief valve, surge tank, condenser, acidifying still and the filter-pressing device being sequentially connected with, and slip enters surge tank after relief valve pressure release, then cools down through condenser, acidifying still acidifying, filter pressing, washing obtains 3,6-dichlorosalicylic acid wet product, finally it is dried to obtain 3,6-dichlorosalicylic acid product.
Embodiment 2
A kind of for production 3, the high-pressure continuous reaction system of 6-dichlorosalicylic acid, including the batching kettle 1 being sequentially connected with, carbon dioxide absorption still 2, reaction under high pressure section and pressure release discharging section；Described reaction under high pressure section includes reacting pipe 3 and the blender 4 being arranged on reacting pipe 3, and described pressure release discharging section includes relief valve 5, surge tank 6, condenser 7, acidifying still 8 and the filter-pressing device 9 being sequentially connected with.
Described batching kettle 1 is connected with described carbon dioxide absorption still 2 by dosing pump, described carbon dioxide absorption still 2 is connected with described reaction under high pressure section by dosing pump, described reaction under high pressure section is connected with described surge tank 6 further through described relief valve 5, described surge tank 6 one end with described condenser 7 again is connected, the other end of described condenser 7 connects described acidifying still 8, and described acidifying still 8 is connected with described filter-pressing device 9 again.
Preferably, described carbon dioxide absorption still 2 forms a unit with described reaction under high pressure section, and this unit is two or more, is connected in series with each other.
Preferably, described carbon dioxide absorption still 2 is two or more, is connected in series with each other.
Preferably, described reaction under high pressure section is two or more, is connected in series with each other.Further, connected by dosing pump between described reaction under high pressure section.
Preferably, described carbon dioxide absorption still 2 is provided with absorption kettle heater, absorption kettle chiller, level display device, attemperating unit, pressure control device and pressure-display device.
Preferably, described blender 4 is static mixer.
Preferably, described blender 4 is two or more.
Preferably, described reaction under high pressure section is provided with heater 10.
Embodiment 3
On the basis of embodiment 1:
Preferably, in step, described 2; the preparation technology of 5-chlorophenesic acid potassium is: under nitrogen protection, by 2,5-chlorophenesic acid is dissolved in dimethylbenzene; prepared 2, the xylene solution of 5-chlorophenesic acid, then potassium hydroxide aqueous solution is under agitation added dropwise to 2; in the xylene solution of 5-chlorophenesic acid, drip complete, be heated to boiling; distillation, when moisture reaches 200ppm in the dimethylbenzene that mensuration distillates, stops distillation; then it is cooled to 20 DEG C, obtains 2,5-chlorophenesic acid potassium liquid.
Preferably, in step, described batching kettle is passed through after dispensing carbon dioxide to protect.
Preferably, in step, described 2,5-chlorophenesic acid potassium, dimethylbenzene, Anhydrous potassium carbonate powder, the mass ratio of dispersant are 1:4:0.5:0.01.
Further, one or more mixture during described dispersant is paraffin, sulfonate, higher fatty acids, Polyethylene Glycol, carboxymethyl cellulose.
Embodiment 4
On the basis of embodiment 1:
Preferably, in step, described 2; the preparation technology of 5-chlorophenesic acid potassium is: under nitrogen protection, by 2,5-chlorophenesic acid is dissolved in dimethylbenzene; prepared 2, the xylene solution of 5-chlorophenesic acid, then potassium hydroxide aqueous solution is under agitation added dropwise to 2; in the xylene solution of 5-chlorophenesic acid, drip complete, be heated to boiling; distillation, when moisture reaches 1800ppm in the dimethylbenzene that mensuration distillates, stops distillation; then it is cooled to 90 DEG C, obtains 2,5-chlorophenesic acid potassium liquid.
Preferably, in step, described batching kettle is passed through after dispensing carbon dioxide to protect.
Preferably, in step, described 2,5-chlorophenesic acid potassium, dimethylbenzene, Anhydrous potassium carbonate powder, the mass ratio of dispersant are 1:6:1.5:0.2.
Further, one or more mixture during described dispersant is paraffin, sulfonate, higher fatty acids, Polyethylene Glycol, carboxymethyl cellulose.
Embodiment 5
On the basis of embodiment 1:
Preferably, in step, described 2; the preparation technology of 5-chlorophenesic acid potassium is: under nitrogen protection, by 2,5-chlorophenesic acid is dissolved in dimethylbenzene; prepared 2, the xylene solution of 5-chlorophenesic acid, then potassium hydroxide aqueous solution is under agitation added dropwise to 2; in the xylene solution of 5-chlorophenesic acid, drip complete, be heated to boiling; distillation, when moisture reaches 1000ppm in the dimethylbenzene that mensuration distillates, stops distillation; then it is cooled to 55 DEG C, obtains 2,5-chlorophenesic acid potassium liquid.
Preferably, in step, described batching kettle is passed through after dispensing carbon dioxide to protect.
Preferably, in step, described 2,5-chlorophenesic acid potassium, dimethylbenzene, Anhydrous potassium carbonate powder, the mass ratio of dispersant are 1:5:1:0.1.
Further, one or more mixture during described dispersant is paraffin, sulfonate, higher fatty acids, Polyethylene Glycol, carboxymethyl cellulose.
Embodiment 6
On the basis of embodiment 1:
Preferably, in step, described 2; the preparation technology of 5-chlorophenesic acid potassium is: under nitrogen protection, by 2,5-chlorophenesic acid is dissolved in dimethylbenzene; prepared 2, the xylene solution of 5-chlorophenesic acid, then potassium hydroxide aqueous solution is under agitation added dropwise to 2; in the xylene solution of 5-chlorophenesic acid, drip complete, be heated to boiling; distillation, when moisture reaches 1500ppm in the dimethylbenzene that mensuration distillates, stops distillation; then it is cooled to 60 DEG C, obtains 2,5-chlorophenesic acid potassium liquid.
Preferably, in step, described batching kettle is passed through after dispensing carbon dioxide to protect.
Preferably, in step, described 2,5-chlorophenesic acid potassium, dimethylbenzene, Anhydrous potassium carbonate powder, the mass ratio of dispersant are 1:5.5:1.2:0.03.
Further, one or more mixture during described dispersant is paraffin, sulfonate, higher fatty acids, Polyethylene Glycol, carboxymethyl cellulose.
Embodiment 7
On the basis of embodiment 1:
Preferably, in stepb, described slip Liquid level in described carbon dioxide absorption still is at submergence stirrer paddle, and 30% that described slip volume is described carbon dioxide absorption still volume.
Preferably, in stepb, described in carry out carbon dioxide absorb time, control kettle temperature 35 DEG C, pressure 3.5MPa, soak time 0.5s.
Preferably, in stepb, when described reaction under high pressure section is reacted, keeping temperature of reaction system 120 DEG C, pressure 5.0MPa, the response time is 1.5 hours.
Embodiment 8
On the basis of embodiment 1:
Preferably, in stepb, described slip Liquid level in described carbon dioxide absorption still is at submergence stirrer paddle, and 80% that described slip volume is described carbon dioxide absorption still volume.
Preferably, in stepb, described in carry out carbon dioxide absorb time, control kettle temperature 170 DEG C, pressure 7.8MPa, soak time 50s.
Preferably, in stepb, when described reaction under high pressure section is reacted, keeping temperature of reaction system 170 DEG C, pressure 7.8MPa, the response time is 6 hours.
Embodiment 9
On the basis of embodiment 1:
Preferably, in stepb, described slip Liquid level in described carbon dioxide absorption still is at submergence stirrer paddle, and 55% that described slip volume is described carbon dioxide absorption still volume.
Preferably, in stepb, described in carry out carbon dioxide absorb time, control kettle temperature 102 DEG C, pressure 5.65MPa, soak time 25s.
Preferably, in stepb, when described reaction under high pressure section is reacted, keeping temperature of reaction system 145 DEG C, pressure 6.4MPa, the response time is 3.75 hours.
Embodiment 10
On the basis of embodiment 1:
Preferably, in stepb, described slip Liquid level in described carbon dioxide absorption still is at submergence stirrer paddle, and 66% that described slip volume is described carbon dioxide absorption still volume.
Preferably, in stepb, described in carry out carbon dioxide absorb time, control kettle temperature 150 DEG C, pressure 5MPa, soak time 30s.
Preferably, in stepb, when described reaction under high pressure section is reacted, keeping temperature of reaction system 130 DEG C, pressure 7MPa, the response time is 5 hours.
Embodiment 11
On the basis of embodiment 1:
Preferably, in step C, described condenser is cooled to 40 DEG C.
Preferably, in step C, the acidifying of described acidifying still, for keeping temperature 40 DEG C, stirs lower hydrochloric acid, regulates pH to 1, is cooled to 0 DEG C.
Embodiment 12
On the basis of embodiment 1:
Preferably, in step C, described condenser is cooled to 100 DEG C.
Preferably, in step C, the acidifying of described acidifying still, for keeping temperature 100 DEG C, stirs lower hydrochloric acid, regulates pH to 3, is cooled to 20 DEG C.
Embodiment 13
On the basis of embodiment 1:
Preferably, in step C, described condenser is cooled to 70 DEG C.
Preferably, in step C, the acidifying of described acidifying still, for keeping temperature 70 C, stirs lower hydrochloric acid, regulates pH to 2, is cooled to 10 DEG C.
Embodiment 14
On the basis of embodiment 1:
Preferably, in step C, described condenser is cooled to 50 DEG C.
Preferably, in step C, the acidifying of described acidifying still, for keeping temperature 50 C, stirs lower hydrochloric acid, regulates pH to 1.5, is cooled to 15 DEG C.