CN117756633A - Application of catalyst in synthesis of dimethyl dicarbonate, synthesis method and production system - Google Patents
Application of catalyst in synthesis of dimethyl dicarbonate, synthesis method and production system Download PDFInfo
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- 239000003054 catalyst Substances 0.000 title claims abstract description 88
- GZDFHIJNHHMENY-UHFFFAOYSA-N Dimethyl dicarbonate Chemical compound COC(=O)OC(=O)OC GZDFHIJNHHMENY-UHFFFAOYSA-N 0.000 title claims abstract description 49
- 235000010300 dimethyl dicarbonate Nutrition 0.000 title claims abstract description 49
- 239000004316 dimethyl dicarbonate Substances 0.000 title claims abstract description 49
- 230000015572 biosynthetic process Effects 0.000 title claims abstract description 9
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 9
- 238000003786 synthesis reaction Methods 0.000 title claims abstract description 9
- 238000001308 synthesis method Methods 0.000 title claims abstract description 6
- 238000006243 chemical reaction Methods 0.000 claims abstract description 53
- 125000000913 palmityl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 claims abstract description 18
- 229920000151 polyglycol Polymers 0.000 claims abstract description 6
- 239000010695 polyglycol Substances 0.000 claims abstract description 6
- 125000000217 alkyl group Chemical group 0.000 claims abstract description 4
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 339
- 239000000047 product Substances 0.000 claims description 95
- 239000012071 phase Substances 0.000 claims description 84
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical group [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 78
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 72
- 239000003513 alkali Substances 0.000 claims description 52
- XMJHPCRAQCTCFT-UHFFFAOYSA-N methyl chloroformate Chemical compound COC(Cl)=O XMJHPCRAQCTCFT-UHFFFAOYSA-N 0.000 claims description 52
- 238000000605 extraction Methods 0.000 claims description 45
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 38
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 36
- 239000003921 oil Substances 0.000 claims description 35
- 239000012074 organic phase Substances 0.000 claims description 35
- 238000000034 method Methods 0.000 claims description 28
- 238000002156 mixing Methods 0.000 claims description 28
- 238000011084 recovery Methods 0.000 claims description 27
- 238000005191 phase separation Methods 0.000 claims description 24
- 238000006386 neutralization reaction Methods 0.000 claims description 20
- 238000003860 storage Methods 0.000 claims description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 19
- 230000008569 process Effects 0.000 claims description 18
- 238000003756 stirring Methods 0.000 claims description 13
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 claims description 12
- 239000012043 crude product Substances 0.000 claims description 12
- 239000007788 liquid Substances 0.000 claims description 12
- 239000002253 acid Substances 0.000 claims description 11
- 238000010992 reflux Methods 0.000 claims description 10
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 6
- 239000002904 solvent Substances 0.000 claims description 4
- 239000002351 wastewater Substances 0.000 claims description 3
- 238000001816 cooling Methods 0.000 claims description 2
- 230000002194 synthesizing effect Effects 0.000 claims description 2
- 238000005406 washing Methods 0.000 claims description 2
- 230000003197 catalytic effect Effects 0.000 abstract description 2
- 239000000243 solution Substances 0.000 description 25
- 239000011259 mixed solution Substances 0.000 description 11
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 9
- 239000000203 mixture Substances 0.000 description 6
- 238000004064 recycling Methods 0.000 description 4
- 239000012535 impurity Substances 0.000 description 3
- 230000014759 maintenance of location Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- -1 tri- (dodecyl) methyl Chemical group 0.000 description 3
- YKGBNAGNNUEZQC-UHFFFAOYSA-N 6-methyl-n,n-bis(6-methylheptyl)heptan-1-amine Chemical compound CC(C)CCCCCN(CCCCCC(C)C)CCCCCC(C)C YKGBNAGNNUEZQC-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 2
- 239000012295 chemical reaction liquid Substances 0.000 description 2
- 238000006482 condensation reaction Methods 0.000 description 2
- 235000013373 food additive Nutrition 0.000 description 2
- 239000002778 food additive Substances 0.000 description 2
- BAVYZALUXZFZLV-UHFFFAOYSA-N mono-methylamine Natural products NC BAVYZALUXZFZLV-UHFFFAOYSA-N 0.000 description 2
- 239000003444 phase transfer catalyst Substances 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 1
- VBIIFPGSPJYLRR-UHFFFAOYSA-M Stearyltrimethylammonium chloride Chemical group [Cl-].CCCCCCCCCCCCCCCCCC[N+](C)(C)C VBIIFPGSPJYLRR-UHFFFAOYSA-M 0.000 description 1
- 150000003973 alkyl amines Chemical class 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000000844 anti-bacterial effect Effects 0.000 description 1
- 239000008346 aqueous phase Substances 0.000 description 1
- 239000003849 aromatic solvent Substances 0.000 description 1
- 239000003899 bactericide agent Substances 0.000 description 1
- JBIROUFYLSSYDX-UHFFFAOYSA-M benzododecinium chloride Chemical compound [Cl-].CCCCCCCCCCCC[N+](C)(C)CC1=CC=CC=C1 JBIROUFYLSSYDX-UHFFFAOYSA-M 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 125000000484 butyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 238000005536 corrosion prevention Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000003085 diluting agent Substances 0.000 description 1
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 238000002309 gasification Methods 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000012454 non-polar solvent Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 230000005501 phase interface Effects 0.000 description 1
- YXJYBPXSEKMEEJ-UHFFFAOYSA-N phosphoric acid;sulfuric acid Chemical compound OP(O)(O)=O.OS(O)(=O)=O YXJYBPXSEKMEEJ-UHFFFAOYSA-N 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 150000003242 quaternary ammonium salts Chemical class 0.000 description 1
- 239000011877 solvent mixture Substances 0.000 description 1
- 230000001954 sterilising effect Effects 0.000 description 1
- 238000004659 sterilization and disinfection Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 235000013616 tea Nutrition 0.000 description 1
- SWZDQOUHBYYPJD-UHFFFAOYSA-N tridodecylamine Chemical compound CCCCCCCCCCCCN(CCCCCCCCCCCC)CCCCCCCCCCCC SWZDQOUHBYYPJD-UHFFFAOYSA-N 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
Landscapes
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses an application of a catalyst in dimethyl dicarbonate synthesis, a synthesis method and a production systemThe catalyst has the following structure:wherein R is 1 Is C 12 ～ 16 Preferably R1 is hexadecyl; r is R 2 For- ((CH) 2 ) 4 O) M ‑(CH 2 CH 2 O) N -a polyglycol of H, m=2-4, n=6-12; r is R 3 Can be H, C to C5 alkyl, or R 2 The same applies. The catalyst is easy to recycle, the catalytic efficiency is high, and the conversion rate is high.
Description
Technical Field
The invention relates to the field of food additive synthesis, in particular to application of a catalyst in dimethyl dicarbonate synthesis, a synthesis method and a production system.
Background
Dimethyl dicarbonate is a self-decomposing cold bactericide, passes through the authentication of European Union scientific food association, the food and drug administration of the United states, the food additive joint expert committee of the world health organization and the like, and is widely applied to the corrosion prevention and sterilization of wine, soda water and tea beverages.
The known synthetic process route of dimethyl dicarbonate mainly comprises the steps of condensation reaction, phase separation, catalyst removal, dehydration, rectification and the like, and similar processes are disclosed in patent CN 107188805A, CN 102219690B. The condensation reaction is that the methyl chloroformate solvent mixture is in contact reaction with alkali liquor, wherein the alkali is an acid binding agent, and organic solvents such as benzene, toluene and the like are used as diluents. The currently used phase transfer catalysts are triisooctylamine, quaternary ammonium salt, dodecyldimethylbenzyl ammonium chloride, tri- (dodecyl) methyl amine chloride, tri- (tetradecyl) methyl amine chloride, tetra- (octaalkyl) amine chloride, etc. In the reaction, it mainly catalyzes the hydrolysis reaction of methyl chloroformate, decomposing into dimethyl carbonate and methanol.
However, these catalysts are not ideal catalysts for the synthesis of dimethyl dicarbonate at present, mainly because most of the above catalysts are readily soluble in water and not in nonpolar solvents, which are used in the synthesis process, which results in the decomposition of methyl chloroformate mainly by reaction in the aqueous phase. Therefore, in order for the phase transfer catalyst to have higher selectivity, it should be high solubility in the organic phase and, furthermore, should have moderate hydrophilicity.
In addition, the current publications involve less recovery of catalyst, resulting in a waste of a large amount of catalyst.
Disclosure of Invention
In order to solve the above technical problems, a first object of the present invention is to provide an application of a catalyst in synthesizing dimethyl dicarbonate, which is beneficial to recycling the catalyst, and has high catalytic efficiency and high conversion rate.
In order to achieve the first object, the present invention provides the following technical solutions: use of a catalyst in the synthesis of dimethyl dicarbonate, the catalyst having the structure:
wherein R is 1 Is C 12 ～ 16 Preferably R1 is hexadecyl;
R 2 for- ((CH) 2 ) 4 O) M -(CH 2 CH 2 O) N -a polyglycol of H, m=2-4, n=6-12;
R 3 can be H, C to C5 alkyl, or R 2 The same applies.
Preferably: r is R 1 Is hexadecyl.
Preferably: r is R 2 For- ((CH) 2 ) 4 O) 2 -(CH 2 CH 2 O) 8 -H。
Preferably: r is R 3 And R is R 2 The same applies.
The invention provides a catalyst with a plurality of alkylanilines and polyglycol structures. Compared with a catalyst only provided with a single alkylamine, the structure provided by the invention has stronger affinity and hydrophobicity for an aromatic solvent, and meanwhile, the long-branched chain polyglycol also has stronger hydrophilicity, so that the structure can better play a role in phase interface catalysis. In addition, the catalyst has strong affinity in the organic phase, and is mainly concentrated in the organic phase after catalytic reaction, thereby being beneficial to recycling the catalyst.
The second object of the present invention is achieved by: a synthesis method of dimethyl dicarbonate, which is characterized by comprising the following steps: adding the catalyst, the solvent and the methyl chloroformate into a reaction vessel, uniformly mixing, dropwise adding alkali liquor at the temperature below 15 ℃, keeping strong stirring in the dropwise adding process, carrying out phase separation after the dropwise adding, washing an organic phase by using concentrated sulfuric acid and/or phosphoric acid, and carrying out phase separation to obtain the dimethyl dicarbonate. The preparation process is simple, and the conversion rate of methyl chloroformate is high. The yield can reach more than 86 percent.
In the scheme, the method comprises the following steps: the solvent is one of benzene and toluene, the addition amount of the catalyst is 1-2% of the mass of methyl chloroformate, the alkali liquor is sodium hydroxide solution or potassium hydroxide solution, and the mass concentration of the alkali liquor is 10-30%. n (methyl chloroformate): n (sodium hydroxide) =1 to 1.4:1.
The third object of the present invention is achieved by: a system for producing dimethyl dicarbonate, characterized in that: comprises an alkali liquor feeding system, an organic phase feeding system, a reaction system, an extraction system, a catalyst recovery system, a toluene rectifying system and a product rectifying system;
the reaction system comprises a reaction kettle, wherein an alkali liquor inlet is formed in the upper part of the reaction kettle and is connected with an alkali liquor feeding system, a reaction liquor outlet pipeline is further formed in the upper part of the reaction kettle and is connected with a phase separator, a reflux pipeline is arranged in the middle of the reaction kettle and is connected with a forced circulation heat exchanger, an inlet pipeline of the forced circulation heat exchanger is connected with a forced circulation pump and an organic phase feeding system, and the forced circulation pump is connected with a circulation pipeline at the bottom end of the reaction kettle; the reaction temperature in the reaction kettle is controlled to be 0-15 ℃;
the organic phase feeding system consists of a methyl chloroformate barrel, a toluene charging barrel, a methyl chloroformate feeding pump, an oil phase mixing kettle, an oil phase feeding pump, a catalyst recovery phase separator, a toluene collecting tank and a toluene feeding pump, wherein the methyl chloroformate barrel is connected with the oil phase mixing kettle through the methyl chloroformate pump, the oil phase feeding pump is connected with a discharge pipeline of the oil phase mixing kettle, an outlet pipeline of the oil phase feeding pump is connected with a forced circulation heat exchanger, the toluene collecting tank and the toluene charging barrel are respectively connected with the toluene feeding pump through pipelines, the toluene feeding pump is connected with the oil phase mixing kettle, a catalyst recovery pipeline of the catalyst recovery phase separator is connected with the oil phase mixing kettle, and the concentration of the fed methyl chloroformate is about 30-70% and the concentration of the catalyst is 0.01-0.5%;
the upper oil phase of the phase separator enters an extraction system, and the lower water phase enters a catalyst recovery system;
the catalyst recovery system comprises a neutralization kettle and a catalyst recovery phase separator; the lower water phase of the phase separator enters a neutralization kettle, and is neutralized with acid liquor from an extraction system in the neutralization kettle, wherein the neutralization temperature is 30-40 ℃; the upper oil phase of the neutralization kettle enters a catalyst recovery separator, and the lower water layer is treated as wastewater;
the extraction system comprises a first concentrated sulfuric acid or phosphoric acid storage tank, a second concentrated sulfuric acid or phosphoric acid storage tank, a first-stage extraction tower and a second-stage extraction tower, wherein an acid inlet at the upper part of the first-stage extraction tower is connected with the first concentrated sulfuric acid or phosphoric acid storage tank, an acid inlet at the upper part of the second-stage extraction tower is connected with the second concentrated sulfuric acid or phosphoric acid storage tank, and organic phase separated from the upper layer of the phase separator is sequentially extracted by the two-stage extraction tower, so that extractant and water in the organic phase are removed; the mass concentration of sulfuric acid is 60-85%, the mass concentration of phosphoric acid is 65-85%, the crude product solution of the secondary extraction tower enters a toluene rectifying system, and the crude product discharged from the toluene rectifying system enters a crude product rectifying system.
In the scheme, the method comprises the following steps: the alkali liquor feeding system consists of an alkali liquor storage tank, an alkali liquor feeding pump and an alkali liquor feeding heat exchanger; the alkali liquor storage tank is connected with an alkali liquor feeding pump, an outlet pipeline of the alkali liquor feeding pump is connected with an alkali liquor feeding heat exchanger, and a discharge pipeline of the alkali liquor feeding heat exchanger is connected with the reaction kettle; and cooling the sodium hydroxide solution by an alkali liquor feeding heat exchanger, and then feeding the sodium hydroxide solution into a reaction kettle, wherein the feeding temperature is 0-10 ℃, and the alkali liquor mass concentration is 10-30%.
In the scheme, the method comprises the following steps: the toluene rectifying system consists of a toluene reboiler, a toluene rectifying tower circulating pump, a toluene condenser and a toluene collecting tank; the crude product solution of the second-stage extraction tower enters the toluene rectifying tower from the middle part of the toluene rectifying tower through a toluene reboiler, a top outlet pipeline of the toluene rectifying tower is connected with a toluene condenser, the toluene condenser is connected with a toluene collecting tank, an outlet pipeline arranged at the bottom of the toluene rectifying tower is connected with a toluene reboiler inlet pipeline through a toluene rectifying tower circulating pump, and the outlet pipeline of the toluene rectifying tower circulating pump is also connected with a top inlet pipeline of the product rectifying tower.
In the scheme, the method comprises the following steps: the product rectification system comprises a product rectification column, a top condenser, a top secondary condenser, a product condenser, a vacuum buffer tank, a product rectification column circulating pump, a product rectification column reboiler, a secondary evaporator, a gas-liquid separator, a heavy component collecting tank and a product collecting tank, wherein a top pipeline of the product rectification column is sequentially connected with the top condenser, the top secondary condenser and the vacuum buffer tank, the vacuum buffer tank is connected with the vacuum system, a product outlet pipeline is arranged at the middle lower part of the side wall of the product rectification column and is connected with the product condenser, an outlet pipeline of the product condenser is divided into two branch pipes, one branch pipe is connected with the product collecting tank, the other branch pipe is connected with a reflux pipeline at the upper part of the product rectification column, a bottom outlet pipeline of the product rectification column is connected with the product rectification column circulating pump, an outlet pipeline of the product rectification column circulating pump is simultaneously connected with the product rectification column reboiler and the secondary evaporator, an outlet pipeline of the product rectification column reboiler is connected with a reflux pipeline at the middle lower part of the product rectification column, a gas-liquid separator is connected with the gas-liquid separator, and the gas-liquid separator is returned to the product rectification column from the gas-phase separator to the upper part of the product rectification column.
The invention can realize continuous production of dimethyl dicarbonate through the system, and realizes recycling of the catalyst through the extraction and neutralization system. The water phase separated from the reaction liquid and the water phase separated from the extraction tower are used for neutralization skillfully, so that the material consumption is reduced. During product rectification, part of the kettle liquid is skillfully transferred to a secondary evaporator, the light component is returned to a product rectifying tower, and the heavy component impurities are collected.
Drawings
FIG. 1 is a process flow diagram of a production system of the present invention.
Detailed Description
The invention is further described below with reference to the drawings and examples.
The catalyst of the invention has the following structure:
wherein R is 1 Is C 12 ～ 16 Preferably R1 is hexadecyl;
R 2 for- ((CH) 2 ) 4 O) M -(CH 2 CH 2 O) N -a polyglycol of H, m=2-4, n=6-12;
R 3 can be H, C to C5 alkyl, or R 2 The same applies.
Example 1
Using catalysts R 1 Is hexadecyl, R 3 Is H, R 2 For C- ((CH) 2 ) 4 O) 2 -(CH 2 CH 2 O) 8 -H。
1.2g of catalyst, 35g of toluene and 65g (0.68 mol) of methyl chloroformate are uniformly mixed, 1767 g of 12% (0.528 mol) sodium hydroxide solution is added dropwise, the temperature is controlled to be less than 15 ℃ during the dropwise adding process, the dropwise adding time is 20min, strong stirring is kept during the dropwise adding process, and phase separation is carried out after the dropwise adding is finished. The organic phase was washed 1 time with 1g of 85% concentrated sulfuric acid and 2g of 75% phosphoric acid, respectively, and the phases were separated to obtain a mixed solution containing dimethyl dicarbonate, methyl chloroformate, and toluene. 40.9g of dimethyl dicarbonate is obtained through rectification, the content is 99.8 percent, and the yield is 88.9 percent.
Example 2
Using catalysts R 1 Is hexadecyl, R 2 、R 3 For C- ((CH) 2 ) 4 O) 2 -(CH2CH2O) 8 -H。
1.2g of catalyst, 35g of toluene and 65g of methyl chloroformate are uniformly mixed, 212g of 10% sodium hydroxide (0.53 mol) solution is dripped into the mixture, the temperature is controlled to be lower than 15 ℃ in the dripping process, the dripping time is 20min, the strong stirring is kept in the dripping process, and phase separation is carried out after the dripping is finished. The organic phase was washed 1 time with 1g of 85% concentrated sulfuric acid and 2g of 75% phosphoric acid, respectively, and the phases were separated to obtain a mixed solution containing dimethyl dicarbonate, methyl chloroformate, and toluene. The rectification yields 43.3g of dimethyl dicarbonate with a content of 99.9% and a yield of 94%.
Example 3
Using catalysts R 1 Is hexadecyl, R 2 、R 3 For C- ((CH) 2 ) 4 O) 2 -(CH 2 CH 2 O) 12 -H。
1.2g of catalyst, 35g of toluene and 65g of methyl chloroformate are uniformly mixed, 74g of 30% sodium hydroxide (0.55 mol) solution is added dropwise, the temperature is controlled to be lower than 15 ℃ during the dropwise addition, the dropwise addition time is 20min, strong stirring is kept during the dropwise addition, and phase separation is carried out after the dropwise addition is completed. The organic phase was washed 1 time with 1g of 85% concentrated sulfuric acid and 2g of 75% phosphoric acid, respectively, and the phases were separated to obtain a mixed solution containing dimethyl dicarbonate, methyl chloroformate, and toluene. The dimethyl dicarbonate is obtained by rectification, the content is 39.4g, the content is 99.8 percent, and the yield is 85.5 percent.
Example 4
Using catalysts R 1 Is hexadecyl, R 3 Is butyl, R 2 For C- ((CH) 2 ) 4 O) 4 -(CH 2 CH 2 O) 6 -H。
Uniformly mixing 1.2g of catalyst, 35g of toluene and 65g of methyl chloroformate, dropwise adding 74g of 30% sodium hydroxide solution into the mixture, controlling the dropwise adding temperature to be lower than 15 ℃ for 20min, keeping strong stirring in the dropwise adding process, and carrying out phase separation after the dropwise adding is finished. The organic phase was washed 1 time with 1g of 85% concentrated sulfuric acid and 2g of 75% phosphoric acid, respectively, and the phases were separated to obtain a mixed solution containing dimethyl dicarbonate, methyl chloroformate, and toluene. 38.5g of dimethyl dicarbonate is obtained by rectification, the content is 99.8 percent, and the yield is 83.5 percent.
Example 5
Using catalysts R 1 Is hexadecyl, R 3 、R 2 For C- ((CH) 2 ) 4 O) 4 -(CH 2 CH 2 O) 6 -H。
Uniformly mixing 1.2g of catalyst, 35g of toluene and 65g of methyl chloroformate, dropwise adding 212g of 10% sodium hydroxide solution, controlling the temperature to be lower than 15 ℃ in the dropwise adding process, dropwise adding for 20min, keeping strong stirring in the dropwise adding process, and carrying out phase separation after dropwise adding is finished. The organic phase was washed 1 time with 1g of 85% concentrated sulfuric acid and 2g of 75% phosphoric acid, respectively, and the phases were separated to obtain a mixed solution containing dimethyl dicarbonate, methyl chloroformate, and toluene. The rectification yields 39.1g of dimethyl dicarbonate with a content of 99.8% and a yield of 85%.
Example 6
Using catalysts R 1 Is hexadecyl, R 3 Is H, R 2 For C- ((CH) 2 ) 4 O) 2 -(CH 2 CH 2 O) 8 -H。
Uniformly mixing 0.65g of catalyst, 35g of toluene and 65g of methyl chloroformate, dropwise adding 176g of 12% sodium hydroxide solution, controlling the dropwise adding temperature to be less than 15 ℃ and dropwise adding time to be 20min, keeping strong stirring in the dropwise adding process, and carrying out phase separation after dropwise adding is finished. The organic phase was washed 1 time with 1g of 85% concentrated sulfuric acid and 2g of 75% phosphoric acid, respectively, and the phases were separated to obtain a mixed solution containing dimethyl dicarbonate, methyl chloroformate, and toluene. 40.1g of dimethyl dicarbonate is obtained through rectification, the content is 99.8 percent, and the yield is 87.1 percent.
Example 7
Using catalysts R 1 Is hexadecyl, R 3 Is H, R 2 For C- ((CH) 2 ) 4 O) 2 -(CH 2 CH 2 O) 8 -H。
Uniformly mixing 1.35g of catalyst, 35g of toluene and 65g of methyl chloroformate, dropwise adding 176g of 12% sodium hydroxide solution, controlling the dropwise adding temperature to be less than 15 ℃ and dropwise adding time to be 20min, keeping strong stirring in the dropwise adding process, and carrying out phase separation after dropwise adding is finished. The organic phase was washed 1 time with 1g of 85% concentrated sulfuric acid and 2g of 75% phosphoric acid, respectively, and the phases were separated to obtain a mixed solution containing dimethyl dicarbonate, methyl chloroformate, and toluene. 40.5g of dimethyl dicarbonate is obtained through rectification, the content is 99.8 percent, and the yield is 88.1 percent.
Example 8
Using catalysts R 1 Is hexadecyl, R 3 Is H, R 2 For C- ((CH) 2 ) 4 O) 2 -(CH 2 CH 2 O) 8 -H。
Uniformly mixing 1.35g of catalyst, 35g of benzene and 65g of methyl chloroformate, dropwise adding 176g of 12% sodium hydroxide solution, controlling the dropwise adding temperature to be less than 15 ℃ and dropwise adding time to be 20min, keeping strong stirring in the dropwise adding process, and carrying out phase separation after dropwise adding is finished. The organic phase was washed 1 time with 1g of 85% concentrated sulfuric acid and 2g of 75% phosphoric acid, respectively, and the phases were separated to obtain a mixed solution containing dimethyl dicarbonate, methyl chloroformate, and toluene. The dimethyl dicarbonate is obtained by rectification, the content is 99.8 percent, and the yield is 86.7 percent.
Example 9
Using catalysts R 1 Is hexadecyl, R 2 、R 3 For C- ((CH) 2 ) 4 O) 2 -(CH 2 CH 2 O) 12 -H。
1.2g of catalyst, 35g of toluene and 65g of methyl chloroformate are uniformly mixed, 102g of 30% potassium hydroxide (0.55 mol) solution is added dropwise, the temperature is controlled to be lower than 15 ℃ during the dropwise addition, the dropwise addition time is 20min, strong stirring is kept during the dropwise addition, and phase separation is carried out after the dropwise addition is completed. The organic phase was washed 1 time with 1g of 85% concentrated sulfuric acid and 2g of 75% phosphoric acid, respectively, and the phases were separated to obtain a mixed solution containing dimethyl dicarbonate, methyl chloroformate, and toluene. 38.2g of dimethyl dicarbonate is obtained by rectification, the content is 99.8 percent, and the yield is 82.8 percent.
Example 10
As shown in figure 1, the production system of dimethyl dicarbonate comprises an alkali liquor feeding system, an organic phase feeding system, a reaction system, an extraction system, a catalyst recovery system, a toluene rectifying system and a product rectifying system.
The reaction system comprises a reaction kettle 4, wherein an alkali liquor inlet is arranged at the upper part of the reaction kettle 4 and is connected with an alkali liquor feeding system, and the alkali liquor feeding system consists of an alkali liquor storage tank 1, an alkali liquor feeding pump 2 and an alkali liquor feeding heat exchanger 3; the alkali liquor storage tank 1 is connected with the alkali liquor feeding pump 2, an outlet pipeline of the alkali liquor feeding pump 2 is connected with the alkali liquor feeding heat exchanger 3, a discharge pipeline of the alkali liquor feeding heat exchanger 3 is connected with the reaction kettle 4, and sodium hydroxide solution enters the reaction kettle after being cooled by the alkali liquor feeding heat exchanger, wherein the feeding temperature is 0-10 ℃, and the mass concentration of the alkali liquor solution is 10-30%. The alkali liquor is sodium hydroxide or potassium hydroxide solution.
The upper portion of reation kettle 4 still is provided with reaction liquid outlet line and links to each other with phase separator 10, the middle part of reation kettle 4 is provided with the return line and links to each other with forced circulation heat exchanger 6, forced circulation heat exchanger 6's inlet line links to each other with forced circulation pump 5 and organic phase feed system, forced circulation pump 5 links to each other with the circulation pipeline of reation kettle 4 bottom. The reaction temperature in the reaction kettle is controlled between 0 and 15 ℃.
The organic phase feeding system consists of a methyl chloroformate barrel 32, a toluene charging barrel 33, a methyl chloroformate feeding pump 7, an oil phase mixing kettle 8, an oil phase feeding pump 9, a catalyst recovery phase separator 16, a toluene collecting tank 20 and a toluene feeding pump 21, wherein the methyl chloroformate barrel 32 is connected with the oil phase mixing kettle 8 through the methyl chloroformate pump 7, the oil phase feeding pump 9 is connected with a discharging pipeline of the oil phase mixing kettle 8, an outlet pipeline of the oil phase feeding pump 9 is connected with a forced circulation heat exchanger 6, the toluene collecting tank 20 and the toluene charging barrel 33 are respectively connected with the toluene feeding pump 21 through pipelines, the toluene feeding pump 21 is connected with the oil phase mixing kettle 8, a catalyst recovery pipeline of the catalyst recovery phase separator 16 is connected with the oil phase mixing kettle 8, and the concentration of the fed methyl chloroformate is about 30-70%, and the concentration of the catalyst is 0.01-0.5%;
the upper oil phase of the phase separator 10 enters an extraction system, and the lower water phase enters a catalyst recovery system.
The catalyst recovery system comprises a neutralization kettle 15 and a catalyst recovery phase separator 16; the lower water phase of the phase separator 10 enters a neutralization kettle 15, and is neutralized with acid liquor from an extraction system in the neutralization kettle 15, wherein the neutralization temperature is 30-40 ℃; the upper oil phase of the neutralization kettle 15 enters a catalyst recovery separator 16, and the lower water layer is treated as wastewater.
The extraction system comprises a first concentrated sulfuric acid or phosphoric acid storage tank 11, a second concentrated sulfuric acid or phosphoric acid storage tank 12, a first-stage extraction tower 13 and a second-stage extraction tower 14, wherein an acid inlet at the upper part of the first-stage extraction tower 13 is connected with the sulfuric acid storage tank 11, an acid inlet at the upper part of the second-stage extraction tower 14 is connected with the second concentrated sulfuric acid or phosphoric acid storage tank 12, and organic phase separated from the upper layer of the phase separator is sequentially extracted by the two-stage extraction tower, so that extractant and water in the organic phase are removed; the first concentrated sulfuric acid or phosphoric acid storage tank 11 and the second concentrated sulfuric acid or phosphoric acid storage tank 12 can be phosphoric acid, or sulfuric acid-phosphoric acid, the mass concentration of the sulfuric acid is 60-85%, the mass concentration of the phosphoric acid is 65-85%, and the crude product solution of the secondary extraction tower 1 enters a toluene rectifying system. And the crude product from the toluene rectifying system enters a crude product rectifying system.
The toluene rectifying system consists of a toluene reboiler 17, a toluene rectifying tower 18, a toluene rectifying tower circulating pump 19, a toluene condenser 34 and a toluene collecting tank 20; the crude product solution of the secondary extraction tower enters the toluene rectifying tower 18 from the middle part of the toluene rectifying tower 18 through the toluene reboiler 17, a top outlet pipeline of the toluene rectifying tower 18 is connected with a toluene condenser 34, the toluene condenser 34 is connected with a toluene collecting tank, an outlet pipeline arranged at the bottom of the toluene rectifying tower is connected with an inlet pipeline of the toluene reboiler 17 through a toluene rectifying tower circulating pump 19, and the outlet pipeline of the toluene rectifying tower circulating pump 19 is also connected with a top inlet pipeline of a product rectifying tower 22.
The product rectification system comprises a product rectification column 22, a top condenser 23, a top secondary condenser 24, a product condenser 25, a vacuum buffer tank 35, a product rectification column circulating pump 26, a product rectification column reboiler 27, a secondary evaporator 28, a gas-liquid separator 29, a heavy component collecting tank 30 and a product collecting tank 31, wherein a top pipeline of the product rectification column is sequentially connected with the top condenser 23, the top secondary condenser 24 and the vacuum buffer tank 35, the vacuum buffer tank 35 is connected with the vacuum system, a product outlet pipeline is arranged at the middle lower part of the side wall of the product rectification column 22 and is connected with the product condenser 25, an outlet pipeline of the product condenser 25 is divided into two branch pipes, one branch pipe is connected with the product collecting tank 31, the other branch pipe is connected with a reflux pipeline at the upper part of the product rectification column, a bottom outlet pipeline of the product rectification column 27 is connected with the product rectification column circulating pump 26, an outlet pipeline of the product rectification column circulating pump 26 is simultaneously connected with the product rectification column reboiler 27 and the secondary evaporator 28, an outlet of the product rectification column reboiler 27 is connected with the reflux pipeline at the lower part of the product rectification column, and the product rectification column is connected with the reflux pipeline of the secondary evaporator 29, and the product rectification column enters the gas-liquid reflux column is separated from the upper part of the product rectification column 30.
Cold materials are fed from the top of the tower, circulation evaporation is realized through a circulating pump and a reboiler, and gas phase is collected through a product condenser 25 in the middle of the rectifying tower, so that a product is obtained. Part of the material which is diverted from the product rectifying tower circulating pump 26 enters the secondary evaporator 28 for re-gasification, heavy components are separated by the gas-liquid separator 29, impurities are continuously removed, and the impurities are collected by the heavy component collecting tank 30.
In this embodiment: using a catalyst R1 is hexadecyl, R3 is H, R2 is C- ((CH) 2 ) 4 O) 2 -(CH 2 CH 2 O) 8 -H。
NaOH is 15% by mass, and is pumped into the reaction kettle 4 through the NaOH feeding pump 2, and the feeding temperature is 5 ℃; the mass concentration of the methyl chloroformate fed is about 65% and the mass concentration of the catalyst is 0.05%.
The feeding ratio of the organic phase mixture to the NaOH solution is as follows: methyl chloroformate to NaOH feed mole ratio 1.04:1.
the reaction temperature is 10 ℃, the phase separation temperature is 15 ℃, and the reaction residence time is 30min.
The organic phase separated from the upper layer of the phase separator 10 is subjected to two-stage extraction of 75% phosphoric acid in the first-stage extraction column 13 and the second-stage extraction column 14. The extracted organic phase enters a toluene rectifying system, and the water phase enters a catalyst recovery system. The phosphoric acid consumption is 1kg phosphoric acid/100 kg methyl chloroformate, the extraction temperature is 30 ℃, and the retention time is 50min.
The acid-containing water phase from the lower part of the extraction tower and the alkali-containing water phase from the lower part of the phase separator 10 are neutralized in a neutralization kettle 15 until the PH value is 8, the neutralization temperature is 30 ℃, the upper oil phase of the neutralization kettle 15 enters a catalyst recovery phase separator 16 for phase separation, the upper layer after phase separation is the recovered catalyst and enters an oil phase mixing kettle 8 for recycling, and the lower layer enters wastewater treatment.
The extracted organic phase enters a toluene rectifying tower 18 for rectification, and the heavy components at the bottom of the tower are pumped into a toluene reboiler 17 for circulation by a toluene rectifying tower circulating pump 19, wherein part of the heavy components are pumped into a product rectifying system. The ratio of the circulating flow to the inlet rectification flow is 8:2, the temperature of the bottom of the tower is 35 ℃, and the absolute pressure is 10kpa.
The product is circularly evaporated in the product rectifying tower 22 through a product rectifying tower circulating pump 26 and a product rectifying tower reboiler 27, the bottom temperature is 30 ℃, the product condenser 25 is 25 ℃, the top condenser 23 is 18 ℃, the top secondary condenser 24 is 10 ℃, and the absolute pressure is 0.8kPa. The circulation pump shunts part of the product to the secondary evaporator 28, the ratio of circulation flow to shunt flow is 8:2, and the temperature of the secondary evaporator 28 is 35 ℃.
After the treatment by the method, the dimethyl dicarbonate product can be obtained, the content is 99.8 percent, and the yield is 88.9 percent.
Example 11 (step same 10)
Using catalysts R 1 Is hexadecyl, R 3 For C- ((CH) 2 ) 4 O) 2 -(CH 2 CH 2 O) 8 -H，R 2 For C- ((CH) 2 ) 4 O) 2 -(CH 2 CH 2 O) 8 -H; pumping methyl chloroformate, toluene and a catalyst into an oil phase mixing kettle (8) through feeding pumps at the positions at the speed of 65kg/h, 35kg/h and 1.23kg/h for uniform mixing;
NaOH solution with 15% mass fraction was pumped in at 145kg/h, and the feeding temperature was kept around 5 ℃.
The reaction: the temperature was 10℃and the reaction residence time was 30min.
And (3) phase separation: the phase separation temperature is 10 ℃, and the phase separation residence time is 60min.
Extraction: (75%) phosphoric acid was extracted 2 times at a flow rate of 1kg/h at 30℃for a residence time of 50min.
And (3) toluene rectification: the bottom temperature was 35℃and the absolute pressure was 10kpa.
And (3) product rectification: the bottom temperature is 30 ℃, the temperature of a condenser (25) is 25 ℃, the temperature of a condenser (23) is 18 ℃, the temperature of a secondary condenser (24) is 10 ℃, and the absolute pressure is 0.8kPa. The circulation pump shunts part of the product to the secondary evaporator (28), and the temperature of the secondary evaporator (28) is 35 ℃.
By the treatment of the method, the dimethyl dicarbonate product can be guessed at the rate of 39.8kg/h, the content of the dimethyl dicarbonate product is 99.8 percent, and the yield is about 90 percent.
Example 12
Using catalysts R 1 Is hexadecyl, R 2 For C- ((CH) 2 ) 4 O) 4 -(CH 2 CH 2 O) 13 -H，R 3 For C- ((CH) 2 ) 4 O) 4 -(CH 2 CH 2 O) 13 -H; 170kg/h of methyl chloroformate and 108kg/h of toluene (containing recovered) are pumped into an oil phase mixing kettle (8) through a feed pump, and the mixture is uniformly mixed and transferred into a reaction kettle (4); 504.3kg/h of 15% NaOH solution and 2.65kg/h of catalyst are pumped into the reaction kettle (4), and the feeding temperature is kept at about 6 ℃.
The reaction: the temperature is 10 ℃, the phase separation temperature is 15 ℃, and the reaction residence time is 30min.
Extraction: 5kg/h of 85% sulfuric acid and 5.5kg/h of 75% phosphoric acid are extracted 1 time each, the extraction temperature is 30 ℃, and the retention time is 50min.
And (3) toluene rectification: the bottom temperature was 35℃and the absolute pressure was 10kpa.
And (3) product rectification: the bottom temperature is 30 ℃, the temperature of a condenser (25) is 25 ℃, the temperature of a condenser (23) is 18 ℃, the temperature of a secondary condenser (24) is 10 ℃, and the absolute pressure is 0.8kPa. The circulation pump shunts part of the product to the secondary evaporator (28), the ratio of circulation flow to shunt flow is 8:2, and the temperature of the secondary evaporator (28) is 35 ℃.
By the treatment of the method, 96kg of dimethyl dicarbonate product can be obtained per hour, the content is 99.8%, and the yield is about 79%.
Example 13 (comparative example 1)
The catalyst is trimethyl octadecyl ammonium chloride.
1.2g of catalyst 50g of toluene and 65g of methyl chloroformate are uniformly mixed, 176g of 12% sodium hydroxide solution is added dropwise into the mixture for 20min, strong stirring is kept in the dropping process, and phase separation is carried out after the dropping is completed. The organic phase was washed 1 time with 1g of 85% concentrated sulfuric acid and 2g of 75% phosphoric acid, respectively, and the phases were separated to obtain a mixed solution containing dimethyl dicarbonate, methyl chloroformate, toluene and methanol. 10.8g of dimethyl dicarbonate is obtained by rectification, and the theoretical yield is 23.4%.
Example 14
The catalyst used was trilaurylamine.
Uniformly mixing 1.2g of catalyst 40g of toluene and 60g of methyl chloroformate, dropwise adding 155g of 12% sodium hydroxide solution into the mixture for 20min, keeping strong stirring in the dropwise adding process, and carrying out phase separation after the dropwise adding is finished. The organic phase was washed 1 time with 1g of 85% concentrated sulfuric acid and 2g of 75% phosphoric acid, respectively, and the phases were separated to obtain a mixed solution containing dimethyl dicarbonate, methyl chloroformate, toluene and methanol. 21.5g of dimethyl dicarbonate is obtained by rectification, and the theoretical yield is 46.6%.
Example 15
The remainder was the same as in example 9, except that triisooctylamine was used as the catalyst.
100kg/h of methyl chloroformate and 67kg/h of toluene (containing recovered) are pumped into an oil phase mixing kettle (8) through a feed pump, and are uniformly mixed and transferred into a reaction kettle (4); 302.3kg/h of 14% NaOH solution and 1.53kg/h of catalyst are pumped into a reaction kettle (4), and the feeding temperature is kept at about 6 ℃.
The reaction: the temperature is 10 ℃, the phase separation temperature is 15 ℃, and the reaction residence time is 30min.
Extraction: 5kg/h of 85% sulfuric acid and 5.5kg/h of 75% phosphoric acid are extracted 1 time each, the extraction temperature is 30 ℃, and the retention time is 50min.
And (3) toluene rectification: the bottom temperature was 35℃and the absolute pressure was 10kpa.
And (3) product rectification: the bottom temperature is 30 ℃, the product condenser 25 temperature is 25 ℃, the top condenser 23 temperature is 18 ℃, the top secondary condenser 24 temperature is 10 ℃, and the absolute pressure is 0.8kPa. The product rectifying tower circulating pump shunts part of the product to the secondary evaporator 28, the ratio of circulating flow to shunting flow is 8:2, and the temperature of the secondary evaporator 28 is 35 ℃.
By the treatment of the method, 29kg of dimethyl dicarbonate product can be obtained per hour, the content is 99.8%, and the yield is about 40.9%.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (10)
1. Use of a catalyst in the synthesis of dimethyl dicarbonate, the catalyst having the structure:
wherein R is 1 Is C 12 ～ 16 Preferably R1 is hexadecyl;
R 2 for- ((CH) 2 ) 4 O) M -(CH 2 CH 2 O) N -a polyglycol of H, m=2-4, n=6-12;
R 3 can be H, C to C5 alkyl, or R 2 The same applies.
2. The use according to claim 1, characterized in that: r is R 1 Is hexadecyl.
3. The use according to claim 1 or 2The method is characterized by comprising the following steps: r is R 2 Is that
-((CH 2 ) 4 O) 2 -(CH 2 CH 2 O) 8 -H。
4. A use according to claim 3, characterized in that: r is R 3 And R is R 2 The same applies.
5. A synthesis method of dimethyl dicarbonate, which is characterized by comprising the following steps: adding the catalyst, the solvent and the methyl chloroformate according to any one of claims 1-4 into a reaction vessel, uniformly mixing, controlling the temperature below 15 ℃, dripping alkali liquor, keeping strong stirring in the dripping process, carrying out phase separation after the dripping, washing an organic phase by using concentrated sulfuric acid and/or phosphoric acid, and carrying out phase separation to obtain the dimethyl dicarbonate.
6. The method for synthesizing dimethyl dicarbonate according to claim 5, wherein: the solvent is one of benzene and toluene, the addition amount of the catalyst is 1-2% of the mass of methyl chloroformate, the alkali liquor is sodium hydroxide solution or potassium hydroxide solution, and the mass concentration of the alkali liquor is 10-30%.
7. A system for producing dimethyl dicarbonate, characterized in that: comprises an alkali liquor feeding system, an organic phase feeding system, a reaction system, an extraction system, a catalyst recovery system, a toluene rectifying system and a product rectifying system;
the reaction system comprises a reaction kettle, wherein an alkali liquor inlet is formed in the upper part of the reaction kettle and is connected with an alkali liquor feeding system, a reaction liquor outlet pipeline is further formed in the upper part of the reaction kettle and is connected with a phase separator, a reflux pipeline is arranged in the middle of the reaction kettle and is connected with a forced circulation heat exchanger, an inlet pipeline of the forced circulation heat exchanger is connected with a forced circulation pump and an organic phase feeding system, and the forced circulation pump is connected with a circulation pipeline at the bottom end of the reaction kettle; the reaction temperature in the reaction kettle is controlled to be 0-15 ℃;
the organic phase feeding system consists of a methyl chloroformate barrel, a toluene charging barrel, a methyl chloroformate feeding pump, an oil phase mixing kettle, an oil phase feeding pump, a catalyst recovery phase separator, a toluene collecting tank and a toluene feeding pump, wherein the methyl chloroformate barrel is connected with the oil phase mixing kettle through the methyl chloroformate pump, the oil phase feeding pump is connected with a discharge pipeline of the oil phase mixing kettle, an outlet pipeline of the oil phase feeding pump is connected with a forced circulation heat exchanger, the toluene collecting tank and the toluene charging barrel are respectively connected with the toluene feeding pump through pipelines, the toluene feeding pump is connected with the oil phase mixing kettle, a catalyst recovery pipeline of the catalyst recovery phase separator is connected with the oil phase mixing kettle, and the concentration of the fed methyl chloroformate is about 30-70% and the concentration of the catalyst is 0.01-0.5%;
the upper oil phase of the phase separator enters an extraction system, and the lower water phase enters a catalyst recovery system;
the catalyst recovery system comprises a neutralization kettle and a catalyst recovery phase separator; the lower water phase of the phase separator enters a neutralization kettle, and is neutralized with acid liquor from an extraction system in the neutralization kettle, wherein the neutralization temperature is 30-40 ℃; the upper oil phase of the neutralization kettle enters a catalyst recovery separator, and the lower water layer is treated as wastewater;
the extraction system comprises a first concentrated sulfuric acid or phosphoric acid storage tank, a second concentrated sulfuric acid or phosphoric acid storage tank, a first-stage extraction tower and a second-stage extraction tower, wherein an acid inlet at the upper part of the first-stage extraction tower is connected with the first concentrated sulfuric acid or phosphoric acid storage tank, an acid inlet at the upper part of the second-stage extraction tower is connected with the second concentrated sulfuric acid or phosphoric acid storage tank, and organic phase separated from the upper layer of the phase separator is sequentially extracted by the two-stage extraction tower, so that extractant and water in the organic phase are removed; the mass concentration of sulfuric acid is 60-85%, the mass concentration of phosphoric acid is 65-85%, the crude product solution of the secondary extraction tower enters a toluene rectifying system, and the crude product discharged from the toluene rectifying system enters a crude product rectifying system.
8. The dimethyl dicarbonate production system according to claim 7, wherein: the alkali liquor feeding system consists of an alkali liquor storage tank, an alkali liquor feeding pump and an alkali liquor feeding heat exchanger; the alkali liquor storage tank is connected with an alkali liquor feeding pump, an outlet pipeline of the alkali liquor feeding pump is connected with an alkali liquor feeding heat exchanger, and a discharge pipeline of the alkali liquor feeding heat exchanger is connected with the reaction kettle; and cooling the sodium hydroxide solution by an alkali liquor feeding heat exchanger, and then feeding the sodium hydroxide solution into a reaction kettle, wherein the feeding temperature is 0-10 ℃, and the alkali liquor mass concentration is 10-30%.
9. The dimethyl dicarbonate production system according to claim 8, wherein: the toluene rectifying system consists of a toluene reboiler, a toluene rectifying tower circulating pump, a toluene condenser and a toluene collecting tank; the crude product solution of the second-stage extraction tower enters the toluene rectifying tower from the middle part of the toluene rectifying tower through a toluene reboiler, a top outlet pipeline of the toluene rectifying tower is connected with a toluene condenser, the toluene condenser is connected with a toluene collecting tank, an outlet pipeline arranged at the bottom of the toluene rectifying tower is connected with a toluene reboiler inlet pipeline through a toluene rectifying tower circulating pump, and the outlet pipeline of the toluene rectifying tower circulating pump is also connected with a top inlet pipeline of the product rectifying tower.
10. The dimethyl dicarbonate production system according to claim 8, wherein: the product rectification system comprises a product rectification column, a top condenser, a top secondary condenser, a product condenser, a vacuum buffer tank, a product rectification column circulating pump, a product rectification column reboiler, a secondary evaporator, a gas-liquid separator, a heavy component collecting tank and a product collecting tank, wherein a top pipeline of the product rectification column is sequentially connected with the top condenser, the top secondary condenser and the vacuum buffer tank, the vacuum buffer tank is connected with the vacuum system, a product outlet pipeline is arranged at the middle lower part of the side wall of the product rectification column and is connected with the product condenser, an outlet pipeline of the product condenser is divided into two branch pipes, one branch pipe is connected with the product collecting tank, the other branch pipe is connected with a reflux pipeline at the upper part of the product rectification column, a bottom outlet pipeline of the product rectification column is connected with the product rectification column circulating pump, an outlet pipeline of the product rectification column circulating pump is simultaneously connected with the product rectification column reboiler and the secondary evaporator, an outlet pipeline of the product rectification column reboiler is connected with a reflux pipeline at the middle lower part of the product rectification column, a gas-liquid separator is connected with the gas-liquid separator, and the gas-liquid separator is returned to the product rectification column from the gas-phase separator to the upper part of the product rectification column.
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