CN114181115A - Salifying system, salifying process and preparation process of trimethyl orthoacetate - Google Patents
Salifying system, salifying process and preparation process of trimethyl orthoacetate Download PDFInfo
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- C07C257/04—Compounds containing carboxyl groups, the doubly-bound oxygen atom of a carboxyl group being replaced by a doubly-bound nitrogen atom, this nitrogen atom not being further bound to an oxygen atom, e.g. imino-ethers, amidines without replacement of the other oxygen atom of the carboxyl group, e.g. imino-ethers
- C07C257/06—Compounds containing carboxyl groups, the doubly-bound oxygen atom of a carboxyl group being replaced by a doubly-bound nitrogen atom, this nitrogen atom not being further bound to an oxygen atom, e.g. imino-ethers, amidines without replacement of the other oxygen atom of the carboxyl group, e.g. imino-ethers having carbon atoms of imino-carboxyl groups bound to hydrogen atoms, to acyclic carbon atoms, or to carbon atoms of rings other than six-membered aromatic rings
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- C07C257/02—Compounds containing carboxyl groups, the doubly-bound oxygen atom of a carboxyl group being replaced by a doubly-bound nitrogen atom, this nitrogen atom not being further bound to an oxygen atom, e.g. imino-ethers, amidines with replacement of the other oxygen atom of the carboxyl group by halogen atoms, e.g. imino-halides
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Abstract
The invention relates to a salification reaction system, salification and preparation process of trimethyl orthoacetate. The invention carries out the dissolution and salification processes of the hydrogen chloride by steps and separate devices, adopts the pipeline mixers which are connected in series, has easy control of reaction temperature, shortens the process time, can realize continuous production, and solves the problems of more reaction heat release, difficult temperature control, long production period and discontinuous production existing in the batch kettle type reaction adopted in the prior art.
Description
Technical Field
The invention relates to the technical field of trimethyl orthoacetate, in particular to a salification and preparation process of trimethyl orthoacetate and a designed reaction system.
Background
Trimethyl orthoacetate (also known as 1,1, 1-trimethoxyethane) is colorless liquid at normal pressure and temperature, has pleasant smell, is insoluble in water, is soluble in organic solvents such as ethanol and diethyl ether, is mainly used as an organic intermediate for synthesizing medicines and pesticides, such as vitamin B1, vitamin A1, sulfadiazine and the like in the field of medicines, and is an intermediate raw material for synthesizing pyrethroid such as cypermethrin, cyhalothrin and the like in the field of agriculture.
At present, the trimethyl orthoacetate is usually produced industrially by an acetonitrile method, the method is mainly completed by three procedures of salification, alcoholysis and rectification, and concretely, dry hydrogen chloride gas is introduced into acetonitrile and methanol in the presence of a solvent to carry out salification reaction to generate ethylimine methyl ether hydrochloride; introducing methanol for alcoholysis to obtain crude trimethyl orthoacetate, and purifying by rectification to obtain pure trimethyl orthoacetate. The salt forming process is an important first step process, and the completion rate and quality of the salt forming process directly influence the time and effect of the whole process.
CN102060678B discloses a trimethyl orthoacetate synthesis process, which comprises mixing acetonitrile, methanol and a nonpolar solvent in a reaction kettle, cooling to-20-5 ℃, introducing hydrogen chloride gas through holes uniformly distributed on a distribution pipe fixed on the inner side wall of the reaction kettle, and fully stirring for reaction to generate hydrochloride; the distribution pipe is a circle or a plurality of circles of coil pipes which are tightly attached to the inner side wall of the reaction kettle and are perpendicular to the direction of the central axis. This patent goes on in kettle-type reactor, through the structure that changes reation kettle, adopts gas distribution pipe evenly to let in hydrogen chloride gas around from the reation kettle inside wall, makes hydrogen chloride gas and reaction mixture can the misce bene, fine improvement reaction system's mixing state, and the alkyl imino acetic ester hydrochloride that forms to crystallization mode homodisperse has improved the reaction yield, and the trimethyl orthoacetate that final alcoholysis obtained. However, the process of dissolving hydrogen chloride in methanol is exothermic reaction, and the salt-forming reaction is also exothermic reaction, and only by adding hydrogen chloride gas dispersedly and stirring uniformly, the improvement of heat release is limited.
CN103910613B discloses a method for producing trimethyl orthoacetate by using hydrogen chloride for producing toluene diisocyanate, which comprises introducing methanol into a dry HCl waste gas at normal pressure and low temperature to produce a byproduct of TDI (toluene diisocyanate), and obtaining alkyd; reacting with acetonitrile in an inert solvent to form salt, and preparing ethylimine methyl ether hydrochloride; introducing two batches of methanol to perform alcoholysis reaction, and distilling to obtain trimethyl orthoacetate. This patent is through the mode of earlier preparation alkyd, has avoided salification reaction and HCl dissolution process to carry out a large amount of heat release that cause simultaneously in same reation kettle to can avoid directly letting in the HCl that reation kettle caused with gaseous HCl excessive, the problem of polluted environment. On the other hand, compared with the method that hydrogen chloride is introduced into the reaction kettle in a gas mode to complete the salt forming reaction in one step, when the HCl dissolution and the salt forming reaction are separately carried out, the method is equivalent to the method that the salt forming process is completed in two steps, so that the total process time for producing trimethyl orthoacetate is increased, the production efficiency is reduced, and the labor cost is increased.
In addition, the salifying process of trimethyl orthoacetate in the prior art is an intermittent kettle type reaction, the single-batch yield is low, the production period is long, multiple charging and discharging are needed, and the industrial production is not facilitated.
Disclosure of Invention
In order to solve the technical problems, the invention provides a salification system, a salification process and a preparation process of trimethyl orthoacetate; by utilizing the salification system, the dissolution of hydrogen chloride and the salification reaction of trimethyl orthoacetate can be carried out simultaneously in different reaction devices, the temperature is convenient to control and is stable, the salification speed is accelerated, the salification process time of trimethyl orthoacetate is shortened, thereby shortening the whole production period of trimethyl orthoacetate, realizing continuous production, being beneficial to industrial production, and the saturated solution of the hydrogen chloride is prepared by adopting a multistage serial pipeline mixer, so that the heat release in the dissolving process of the hydrogen chloride can be slowed down, and when a large amount of hydrogen chloride is introduced into the methanol, the method solves the problems that in the prior art, the whole salification reaction is carried out by adopting a kettle type reactor, the reaction heat release is large, the temperature is not easy to control, the production period is long, and the continuous production cannot be realized.
The invention provides a salification reaction system of trimethyl orthoacetate, which comprises a hydrogen chloride saturated solution preparation device, a gas-liquid separation device and a salification reaction device which are sequentially connected.
The preparation device of the saturated solution of the hydrogen chloride comprises n stages of pipeline mixers which are sequentially connected in series, wherein n is more than or equal to 2, each stage of pipeline mixer is connected with a hydrogen chloride inlet pipe, the 1 st stage of pipeline mixer is connected with a first inlet pipe, the first inlet pipe is used for inputting the methanol and the solvent, and the hydrogen chloride gas is dissolved into the mixed liquid of the methanol and the solvent to obtain the saturated solution of the hydrogen chloride.
The process of dissolving hydrogen chloride gas by using methanol is an exothermic process, the invention adopts a multistage series pipeline mixer to gradually dissolve hydrogen chloride in methanol, can slow down the heat release in the hydrogen chloride dissolving process, avoids the problem that the solution temperature is sharply increased when a large amount of hydrogen chloride is introduced into the methanol to cause the reduction of the hydrogen chloride solubility, is easier to control the materials in the pipeline mixer to be in a stable low-temperature environment by adopting the multistage series pipeline mixer, and can keep the materials at a low temperature because the mass of the solvent is far greater than that of the methanol after the solvent is mixed with the methanol, the solvent can absorb a part of heat release, and can realize the continuous preparation of the saturated hydrogen chloride methanol solution.
The outlet of the nth-stage pipeline mixer is connected with the inlet of the gas-liquid separation device and is used for separating unabsorbed hydrogen chloride gas and saturated solution of hydrogen chloride;
salify reaction unit, salify reaction unit include first feed inlet and second feed inlet, and first feed inlet is used for letting in acetonitrile to salify reaction unit, and the second feed inlet is connected with gas-liquid separation device's liquid outlet, and the saturated solution of hydrogen chloride and acetonitrile carry out salify reaction in salify reaction unit.
Furthermore, a gas outlet of the gas-liquid separation device is connected with a hydrogen chloride gas recovery pipe, an outlet end of the hydrogen chloride gas recovery pipe is connected with a hydrogen chloride gas inlet pipe in the first-stage pipeline mixer, and undissolved hydrogen chloride gas reenters the 1 st-stage or nth-stage pipeline mixer, so that the waste of hydrogen chloride gas and the pollution to the environment are avoided.
Further, each stage of pipeline mixer comprises an interlayer for introducing circulating frozen brine, and a circulating frozen brine system is connected to the interlayer, so that materials in the pipeline mixer can be kept under a set low-temperature condition. The process of dissolving hydrogen chloride gas by methanol is a heat release process, so that the temperature of the material is increased, the solubility of the hydrogen chloride gas in the methanol is reduced, and a circulating freezing brine system is required to maintain a low-temperature environment.
Furthermore, the salification reaction device comprises a plurality of salification reaction kettles connected in parallel, and the heat release of the reaction can be slowed down.
Furthermore, a buffer kettle can be added behind each salification reaction kettle, so that the residence time is increased, the reaction is more sufficient, and the product yield is improved.
In order to solve the problems that the temperature is not easy to control and side reactions are increased due to heat release in the salt forming process, the invention firstly carries out the dissolution of hydrogen chloride and the salt forming reaction of trimethyl orthoacetate in different reaction devices, and separates the two heat release steps of the dissolution of the hydrogen chloride and the salt forming of the trimethyl orthoacetate; secondly, the saturated solution of the hydrogen chloride is prepared by adopting the multistage pipeline mixers which are connected in series, so that the problem of heat release in the dissolving process of the hydrogen chloride can be better controlled, and the solubility of the hydrogen chloride gas in the saturated solution is improved; in addition, in the process of preparing the saturated solution of the hydrogen chloride, the solvent is mixed with the methanol, and the solvent is used for absorbing part of heat release, so that the low temperature of the material is favorably kept; finally, salifying reaction kettles connected in parallel can be used for slowing down the reaction heat release.
In order to shorten the production time and realize continuous production, the invention firstly carries out the dissolution of hydrogen chloride and the salification reaction of trimethyl orthoacetate in different reaction devices, so that the dissolution of hydrogen chloride and the salification reaction of trimethyl orthoacetate are carried out simultaneously; secondly, the saturated hydrogen chloride solution with high solubility can accelerate the salt formation rate and shorten the salt formation time; finally, the continuous production of trimethyl orthoacetate by the salification process can be realized.
The system, a salification method of trimethyl orthoacetate, comprises the following steps:
preparation of a saturated solution of hydrogen chloride: dissolving hydrogen chloride gas into a mixed solution of methanol and a solvent in each stage of the pipeline mixer to obtain a saturated solution of hydrogen chloride;
gas-liquid separation: separating unabsorbed hydrogen chloride gas from a saturated solution of hydrogen chloride in a gas-liquid separation device;
salt forming reaction: introducing the hydrogen chloride saturated solution and acetonitrile into a salifying device, and carrying out salifying reaction to obtain ethylimine methyl ether hydrochloride;
the preparation of the hydrogen chloride saturated solution and the salt-forming reaction are carried out simultaneously in the salt-forming reaction system.
Further, in the step (1), when the serial pipeline mixer is used, methanol and a solvent are introduced into the bottom of the first-stage pipeline mixer, and when the liquid is filled in the first-stage pipeline mixer or the liquid height in the first-stage pipeline mixer in the vertical direction is greater than the height of a hydrogen chloride gas inlet, the hydrogen chloride gas can be in contact with the liquid in time when being introduced into the pipeline reactor; then the material in the first-stage pipeline mixer enters a second-stage pipeline mixer, and then hydrogen chloride gas is introduced from the second-stage pipeline mixer, and the rest is repeated. Preferably, the aeration rate of the second stage pipeline mixer is lower than that of the first stage pipeline mixer.
Further, in the step (1), the temperature of the hydrogen chloride saturated solution in each stage of the pipeline mixer is-20 ℃ to-5 ℃. As the solubility of the hydrogen chloride in the methanol is increased along with the decrease of the temperature, the temperature of the materials in the pipeline mixer needs to be controlled to be-20 ℃ to-5 ℃ in order to increase the solubility of the hydrogen chloride. And at a certain temperature, the solubility of the hydrogen chloride in the methanol is known, so that the hydrogen chloride introduced into the salt-forming reaction kettle can be accurately metered, in addition, the materials are all liquid and can also be metered by a flowmeter, various reaction materials can be introduced according to the proportion of reactants, and the utilization rate of the raw materials is improved.
Furthermore, in the step (1), the retention time of the hydrogen chloride gas in the serially connected multistage tubular reactors is 1.5-3 h.
Further, in the step (1), the mass flow ratio of the methanol to the solvent is 1: 3-5.
Further, in the step (1), the mass flow ratio of the total introduced hydrogen chloride to the methanol is 1.1-1.6: 1. The total introduced hydrogen chloride gas needs to be excessive, so that saturated solution of hydrogen chloride can be formed in the multistage series pipeline mixer, and the redundant hydrogen chloride gas can be used for subsequent separation and recovery.
Further, in the step (1), the solvent is one or more of n-hexane, petroleum ether, pseudocumene, mesitylene and solvent oil.
Further, in the step (2), the unabsorbed hydrogen chloride gas separated from the gas-liquid separation device is recovered and used for preparing a saturated solution of hydrogen chloride, and the recovered hydrogen chloride gas can be introduced into any one of the pipeline mixers of the 1 st stage or the nth stage connected in series.
Further, the salt forming reaction temperature of the step (3) is 10-30 ℃.
Further, the mass flow ratio of the hydrogen chloride saturated solution in the step (3) to the acetonitrile is 4-6: 1. Under the condition that the material temperature is confirmed, the solubility of hydrogen chloride is confirmed to can accurately measure out the quality of hydrogen chloride that lets in into the salt cauldron, and the material is liquid, can realize the accurate measurement of hydrogen chloride that lets in into among the salification reation kettle and control, thereby improve the utilization ratio of raw materials, reduce the loss of raw materials hydrogen chloride.
Further, the preparation method of trimethyl orthoacetate comprises the salification process from the step (1) to the step (3), and also comprises the steps of (4) alcoholysis and (5) rectification.
Further, the alcoholysis in the step (4) comprises introducing ammonia gas into the ethylimine methyl ether hydrochloride obtained after the salt forming reaction, adjusting the pH to be 5-6, then adding methanol, slowly heating to 35-45 ℃, maintaining the temperature for reacting for 6-10 h, and finishing the alcoholysis reaction;
further, the rectification in the step (5) comprises cooling the alcoholysis reaction liquid, filtering, separating and recovering ammonium chloride, and rectifying the filtrate to obtain the trimethyl orthoacetate product.
Compared with the prior art, the invention has the following beneficial effects:
1. the method comprises the steps of dissolving hydrogen chloride in a frozen mixed solution of methanol and a solvent to form a saturated hydrogen chloride solution, carrying out a salt forming reaction with acetonitrile, wherein the dissolving and the salt forming are carried out in different reaction devices, so that the phenomenon that the local temperature is too high and byproducts are increased due to severe heat release can be avoided; and the whole process time can be shortened, and the production efficiency can be improved.
2. The preparation of the saturated solution of hydrogen chloride is carried out in the multistage pipeline mixers which are connected in series, the heat release can be slowed down, and the solubility of the saturated hydrogen chloride solution is improved, so that the salt forming speed is accelerated.
3. The invention can realize the accurate measurement and control of the hydrogen chloride introduced into the salifying reaction kettle, improve the utilization rate of raw materials, is favorable for controlling the reaction heat release, avoids the waste of hydrogen chloride gas and can realize continuous production.
Compared with the prior art, the whole salt forming reaction is carried out in the kettle type reactor, the reaction heat release is more, the temperature is not easy to control, the production period is long, and the continuous production cannot be realized.
Drawings
FIG. 1 is a trimethyl orthoacetate salt formation reaction system according to an embodiment of the present invention;
FIG. 2 is a trimethyl orthoacetate salt formation reaction system according to another embodiment of the present invention.
Detailed Description
The salt-forming reaction system, process and preparation process of trimethyl orthoacetate provided by the present invention will be further described below.
Fig. 1 is a trimethyl orthoacetate salt-forming reaction system according to an embodiment of the present invention, as shown in fig. 1, the salt-forming reaction system includes:
the saturated solution preparation device of the hydrogen chloride comprises a two-stage pipeline mixer 1 which is connected in series, wherein both the two-stage pipeline mixer are connected with a hydrogen chloride inlet pipe 11, the 1 st-stage pipeline mixer is connected with a first inlet pipe 12, and the first inlet pipe is used for inputting methanol and a solvent; dissolving hydrogen chloride gas into a mixed solution of methanol and a solvent to obtain a saturated solution of hydrogen chloride; either stage of the pipeline mixer includes a recycle chilled brine system 13 including a chilled brine inlet 131 and a chilled brine outlet 132.
The gas-liquid separation device 2 comprises an inlet 21, a liquid outlet 22 and a gas outlet 23, wherein the outlet of the 2 nd-stage pipeline mixer is connected with the inlet 21 of the gas-liquid separation device and is used for separating unabsorbed hydrogen chloride gas and saturated solution of hydrogen chloride;
salification reaction unit 3, including two salification reation kettle that connect in parallel, every salification reation kettle includes first feed inlet 31 and second feed inlet 32, and first feed inlet is arranged in letting in acetonitrile to salification reation kettle, and the second feed inlet is connected with gas-liquid separation device's liquid outlet, and every salification reation kettle is connected with buffer tank 4, and the saturated solution of hydrogen chloride carries out salification reaction with methyl alcohol, acetonitrile in salification reation device, obtains the methyl ether hydrochloride of ethylimine.
Example 1
Example 1 the salification reaction system of trimethyl orthoacetate shown in figure 1 was used.
The preparation method of trimethyl orthoacetate comprises the following steps:
(1) preparing a saturated solution of hydrogen chloride, wherein the temperature of the saturated solution of hydrogen chloride in the two-stage pipeline mixer is-20 ℃, 200kg/h of methanol and 800kg/h of solvent n-hexane are introduced from the bottom of the first-stage pipeline mixer, 200kg/h of hydrogen chloride gas is introduced into the first-stage pipeline mixer, 100kg/h of hydrogen chloride gas is introduced into the second-stage pipeline mixer, and the mixing retention time in the two-stage pipeline mixer is 2 h;
(2) and (4) feeding the material at the outlet of the second-stage pipeline mixer into a gas-liquid separation device to obtain a hydrogen chloride saturated solution. The outlet end of the hydrogen chloride gas recovery pipe is connected with a hydrogen chloride inlet pipeline in the first-stage pipeline mixer, and redundant hydrogen chloride gas can be recovered and reenters the first-stage pipeline mixer;
(3) adding the hydrogen chloride saturated solution into two salt forming kettles at the flow rate of 1200kg/h (the flow rate of the hydrogen chloride saturated solution added into each salt forming reaction kettle is 600 kg/h), simultaneously adding acetonitrile 240kg/h (the flow rate of the acetonitrile added into each salt forming reaction kettle is 120 kg/h) into the salt forming kettles, gradually raising the reaction temperature to 20 ℃, ensuring that the whole salt forming device stays for 6h, and finishing the salt forming reaction to obtain an ethylimine methyl ether hydrochloride intermediate;
(4) putting the materials in the salt forming kettle into an alcoholysis reaction kettle, introducing ammonia gas into the salt forming kettle, adjusting the pH to be =5.5, adding 810kg/h of methanol into the solution after the adjustment is finished, slowly heating to 35 ℃, and maintaining the temperature for reaction for 8 h;
(5) after the alcoholysis reaction is finished, cooling the alcoholysis material, centrifuging, filtering and recovering ammonium chloride, and rectifying the filtrate to obtain the trimethyl orthoacetate with the purity of 99.23% and the yield of 89.24%.
Examples 2 to 4
Examples 2 to 4 the salt-forming reaction system of example 1 was the same, and the preparation method thereof was different in that: the temperature of the materials in the two-stage pipeline mixer in the step (1) and the amount of the hydrogen chloride gas introduced into the two-stage pipeline mixer, and other steps are the same as those in the example 1. The process parameters of examples 2 to 4 are shown in Table 1, and the purity and yield of trimethyl orthoacetate obtained are shown in Table 1.
Example 5
Example 5 is the same as the salt formation reaction system of example 1.
The preparation method of trimethyl orthoacetate comprises the following steps:
(1) preparing a saturated solution of hydrogen chloride, wherein the temperature of the saturated solution of hydrogen chloride in the two-stage pipeline mixer is-15 ℃, 200kg/h of methanol and 1000kg/h of solvent n-hexane are introduced from the bottom of the first-stage pipeline mixer, 140kg/h of hydrogen chloride gas is introduced into the second-stage pipeline mixer, and the mixing residence time in the two-stage pipeline mixer is 2 h;
the step (2) is the same as in example 1;
(3) adding hydrogen chloride saturated solution into two salt forming kettles at the flow rate of 1400kg/h (the flow rate of the hydrogen chloride saturated solution added into each salt forming reaction kettle is 700 kg/h), simultaneously adding acetonitrile into the salt forming kettles at the flow rate of 250kg/h, adding acetonitrile into each salt forming reaction kettle at the flow rate of 125 kg/h), gradually increasing the reaction temperature to 30 ℃, ensuring that the whole salt forming device stays for 7h, and finishing the salt forming reaction to obtain an ethylimine methyl ether hydrochloride intermediate;
the procedure in steps (4) and (5) was the same as in example 1, and the purity and yield of the resulting trimethyl orthoacetate product are shown in Table 1.
Example 6
Example 6 is the same as the salt formation reaction system of example 1.
The preparation method of trimethyl orthoacetate comprises the following steps:
(1) preparing a saturated solution of hydrogen chloride, wherein the temperature of the saturated solution of hydrogen chloride in the two-stage pipeline mixer is-15 ℃, 200kg/h of methanol and 600kg/h of solvent n-hexane are introduced from the bottom of the first-stage pipeline mixer, 180kg/h of hydrogen chloride gas is introduced into the first-stage pipeline mixer, 110kg/h of hydrogen chloride gas is introduced into the second-stage pipeline mixer, and the mixing retention time in the two-stage pipeline mixer is 2 h;
the step (2) is the same as in example 1;
(3) adding a hydrogen chloride saturated solution into a salt forming kettle at a flow rate of 1000kg/h (the flow rate of the hydrogen chloride saturated solution added into each salt forming reaction kettle is 500 kg/h), simultaneously adding 220kg/h of acetonitrile into the salt forming kettle (the flow rate of the acetonitrile added into each salt forming reaction kettle is 110 kg/h), gradually increasing the reaction temperature to 30 ℃, keeping the residence time of the whole salt forming device to be 7h, and finishing the salt forming reaction to obtain an ethylimine methyl ether hydrochloride intermediate;
steps (4) and (5) were the same as in example 1. The purity and yield of the resulting product, trimethyl orthoacetate, are also given in Table 1.
TABLE 1
| Fruit of Chinese wolfberry Applying (a) to Example (b) | Pipeline mixing Temperature in the device (℃) | Dissolving hydrogen chloride Degree (g/100g) | Flow rate of methanol (kg/h) | Flow rate of solvent (kg/h) | Second stage chlorine Flow rate of hydrogen hydride (kg/h) | Second stage chlorine Flow rate of hydrogen hydride (kg/h) | Flow rate of acetonitrile (kg/h) | Salt formation reaction Temperature of reaction (℃) | Trimethyl orthoacetate Ester purity (%) | Orthoacetic acid III Yield of methyl ester （%） |
| 1 | -15 | 122.3 | 200 | 800 | 200 | 100 | 240 | 20 | 99.23 | 89.24 |
| 2 | -20 | 130.3 | 200 | 800 | 180 | 90 | 240 | 20 | 99.12 | 88.75 |
| 3 | -10 | 114.8 | 200 | 800 | 170 | 85 | 240 | 20 | 99.11 | 85.81 |
| 4 | -5 | 107.7 | 200 | 800 | 160 | 80 | 240 | 20 | 99.16 | 83.54 |
| 5 | -15 | 122.3 | 200 | 1000 | 140 | 140 | 250 | 30 | 99.17 | 87.53 |
| 6 | -15 | 122.3 | 200 | 600 | 180 | 110 | 220 | 30 | 99.16 | 89.03 |
Example 7
Example 7 the salification reaction system of trimethyl orthoacetate of figure 2 was used, the salification reaction system shown in figure 2 being different from the salification reaction system of figure 1 in that a three-stage pipeline mixer in series was used.
The preparation method of trimethyl orthoacetate comprises the following steps:
(1) preparing a saturated solution of hydrogen chloride, wherein the temperature of the saturated solution of hydrogen chloride in the two-stage pipeline mixer is-15 ℃, 200kg/h of methanol and 800kg/h of solvent n-hexane are introduced from the bottom of the first-stage pipeline mixer, 135kg/h of hydrogen chloride gas is introduced into the first-stage pipeline mixer, 90kg/h of hydrogen chloride gas is introduced into the second-stage pipeline mixer, 40kg/h of hydrogen chloride gas is introduced into the third-stage pipeline mixer, and the mixing retention time in the third-stage pipeline mixer is 1.5 h;
step (2) - (step (5) the same as example 1 gave a product having a triethyl orthoacetate purity of 99.16% and a yield of 89.13%.
COMPARATIVE EXAMPLE 1 (following a procedure analogous to CN 103910613B)
Adding 1200kg of methanol into a kettle type mixer, then introducing 1450kg of slow hydrogen chloride gas to dissolve the hydrogen chloride gas into the methanol, and completing the dissolution within 6 hours, wherein most of the hydrogen chloride gas is not absorbed, the dissolving amount of the hydrogen chloride in the obtained solution is lower, then adding 5840kg of n-hexane and 1440kg of acetonitrile serving as solvents into a reaction kettle, gradually raising the reaction temperature to 20 ℃, maintaining the temperature for reaction for 10 hours, and finishing the salt forming reaction to obtain an ethyliminomethyl ether hydrochloride intermediate; putting the materials in the salt forming kettle into an alcoholysis reaction kettle, introducing ammonia gas into the salt forming kettle, adjusting the pH to be =5.5, adding 2250kg of methanol into the solution after the adjustment is finished, slowly heating to 35 ℃, and maintaining the temperature for reaction for 8 hours; after the alcoholysis reaction is finished, the alcoholysis product liquid is cooled, centrifuged and filtered to recover ammonium chloride, and the filtrate is rectified to obtain 3646 kg of trimethyl orthoacetate with the purity of 98.70% and the yield of 80.75%.
Compared with example 1, comparative example 1 requires a long production period, and the temperature during the reaction process is not easy to control, and local temperature is extremely easy to be overhigh, so that the increase of byproducts is caused. And the mode in comparative example 1 can not realize continuous production, and the product is low in single-batch yield, and needs to be loaded and unloaded for many times when the demand is large.
The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed.
Claims (10)
1. A salification reaction system of trimethyl orthoacetate is characterized by comprising a hydrogen chloride saturated solution preparation device, a gas-liquid separation device and a salification reaction device which are sequentially connected; wherein the content of the first and second substances,
the hydrogen chloride saturated solution preparation device comprises n stages of pipeline mixers which are sequentially connected in series, wherein n is more than or equal to 2, each stage of pipeline mixer is connected with a hydrogen chloride inlet pipe, the 1 st stage of pipeline mixer is connected with a first inlet pipe, and the first inlet pipe is used for inputting methanol and a solvent;
the outlet of the nth-stage pipeline mixer is connected with the inlet of the gas-liquid separation device;
salify reaction unit includes first feed inlet and second feed inlet, first feed inlet be used for to salify reaction unit lets in acetonitrile, the second feed inlet with gas-liquid separation device's liquid outlet connects, the saturated solution of hydrogen chloride and acetonitrile carry out salify reaction in salify reaction unit.
2. The salt-forming reaction system according to claim 1, wherein a gas outlet of the gas-liquid separation device is connected with a hydrogen chloride gas recovery pipe, an outlet end of the hydrogen chloride gas recovery pipe is connected with a hydrogen chloride gas inlet pipe in the 1 st-stage or nth-stage pipeline mixer, and undissolved hydrogen chloride gas reenters the 1 st-stage or nth-stage pipeline mixer.
3. The salt-forming reaction system of claim 1, wherein the salt-forming reaction device comprises salt-forming reaction kettles connected in parallel, and each salt-forming reaction kettle is connected with a buffer kettle.
4. The salt-forming reaction system of claim 1 wherein each stage of the line mixer is coupled to a recirculating chilled brine system.
5. A salification process of trimethyl orthoacetate, characterized in that the salification process is carried out in the salification reaction system of any one of claims 1 to 4, and comprises the following steps:
(1) preparation of a saturated solution of hydrogen chloride: dissolving hydrogen chloride gas into a mixed solution of methanol and a solvent in each stage of the pipeline mixer to obtain a saturated solution of hydrogen chloride;
(2) gas-liquid separation: separating unabsorbed hydrogen chloride gas from a saturated solution of hydrogen chloride in a gas-liquid separation device;
(3) salt forming reaction: introducing the hydrogen chloride saturated solution and acetonitrile into a salt forming reaction device, and carrying out salt forming reaction to obtain ethylimine methyl ether hydrochloride;
the preparation of the hydrogen chloride saturated solution and the salt-forming reaction are carried out simultaneously in the salt-forming reaction system.
6. A salt-forming process according to claim 5, wherein in the step (1), the temperature of the hydrogen chloride saturated solution in each stage of the pipeline mixer is-20 to-5 ℃.
7. The salification process according to claim 5, wherein in the step (1), the feeding mass flow ratio of the methanol to the solvent is 1: 3-5; and/or the mass flow ratio of the total introduced hydrogen chloride to the feeding mass flow of the methanol is 1.1-1.6: 1.
8. The salt forming process according to claim 5, wherein the salt forming reaction temperature in the step (3) is 10-30 ℃, and/or the mass flow ratio of the saturated hydrogen chloride solution to the acetonitrile is 4-6: 1.
9. The process for producing salt as claimed in claim 5, wherein the unabsorbed hydrogen chloride gas separated from the gas-liquid separator is recovered and used for producing a saturated solution of hydrogen chloride.
10. A method for preparing triethyl orthoacetate, comprising the salt formation process of any one of claims 5 to 9, further comprising:
(4) alcoholysis: introducing ammonia gas into the ethylimine methyl ether hydrochloride obtained after the salt forming reaction, adjusting the pH to be 5-6, then adding methanol, slowly heating to 35-45 ℃, maintaining the temperature for reacting for 6-10 h, and finishing the alcoholysis reaction;
(5) and (3) rectification: cooling the alcoholysis reaction liquid, filtering, separating and recovering ammonium chloride, and rectifying the filtrate to obtain trimethyl orthoacetate.
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