Application of catalyst in synthesis of dimethyl dicarbonate, synthesis method and production system

Abstract

The invention discloses an application of a catalyst in synthesis of dimethyl dicarbonate, a synthesis method and a production system, the catalyst has the following structure: # imgabs0 #, wherein R1 is C12-16 alkyl, preferably R1 is hexadecyl; r2 is poly dihydric alcohol of-((CH2) 4O) M-(CH2CH2O) N-H, M is equal to 2 to 4, and N is equal to 6 to 12; and R3 can be H, C1-C5 alkyl, or is the same as R2. The catalyst can be recycled, the catalytic efficiency is high, and the conversion rate is high.

Description

Technical Field

[0001] The invention relates to the field of food additive synthesis, and in particular to application of a catalyst in the synthesis of dimethyl dicarbonate, a synthesis method and a production system. Background Art

[0002] Dimethyl dicarbonate is a "self-degradable cold sterilant" that has been certified by the European Union's Scientific Food Association, the U.S. Food and Drug Administration, the World Health Organization's Joint Expert Committee on Food Additives, etc., and is widely used in the preservation and sterilization of wine, soda, and tea beverages.

[0003] The process route of known dimethyl dicarbonate synthesis mainly contains steps such as condensation reaction, phase separation, catalyst removal, dehydration, rectification, and similar processes are disclosed in patents CN 107188805A and CN 102219690 B. Condensation reaction is the contact reaction of methyl chloroformate solvent mixture and alkali solution, wherein alkali is acid binding agent, and organic solvents such as benzene and toluene are used as diluents. The phase transfer catalyst currently used has tri-isooctylamine, quaternary ammonium salt, dodecyl dimethyl benzyl ammonium chloride, tri-(dodecyl) methyl ammonium chloride, tri-(tetradecyl) methyl ammonium chloride and tetra-(octadecyl) ammonium chloride etc. In the reaction, it mainly catalyzes the hydrolysis reaction of methyl chloroformate, decomposes into dimethyl carbonate and methanol.

[0004] However, these catalysts are not ideal catalysts for the synthesis of dimethyl dicarbonate at present, mainly because the above catalysts are mostly soluble in water and not easily soluble in non-polar solvents, and the synthesis process uses non-polar solvents, which will cause methyl chloroformate to react and decompose mainly in the aqueous phase. Therefore, in order to make the phase-transfer catalyst have higher selectivity, the phase-transfer catalyst should have high solubility in the organic phase and should also have moderate hydrophilicity in addition.

[0005] In addition, the current public literature rarely involves catalyst recovery, resulting in a large amount of catalyst waste. Summary of the invention

[0006] In order to solve the above technical problems, the first purpose of the present invention is to provide an application of a catalyst in the synthesis of dimethyl dicarbonate, which is beneficial to the recovery and reuse of the catalyst, has high catalytic efficiency and high conversion rate. The second purpose is to provide a method for synthesizing dimethyl dicarbonate. The third purpose is to provide a new production system of dimethyl dicarbonate, which improves the production efficiency of dimethyl dicarbonate and can recover the catalyst.

[0007] To achieve the above first object, the present invention provides the following technical solution: an application of a catalyst in the synthesis of dimethyl dicarbonate, characterized in that the catalyst has the following structure:

[0008] Where R1 is C 12 ~ 16 An alkyl group, preferably R1 is hexadecyl;

[0009] R2 is -((CH2)4O) M -(CH2CH2O) N -H polyglycol, M = 2 to 4, N = 6 to 12;

[0010] R3 may be H, a C1-C5 alkyl group, or the same as R2.

[0011] Preferably: R1 is hexadecyl.

[0012] Preferably: R2 is -((CH2)4O)2-(CH2CH2O)8-H.

[0013] Preferably: R3 is the same as R2.

[0014] The present invention provides a catalyst having a structure of multiple alkylanilines and polyglycols. Compared with a catalyst having only a single alkylamine, the structure provided by the present invention has stronger affinity for aromatic solvents and stronger hydrophobicity, and the long-branched polyglycols also have strong hydrophilicity, so that the structure can better achieve a phase interface catalytic effect. In addition, the catalyst has a strong affinity in an organic phase, and is mainly concentrated in the organic phase after the catalytic reaction, which is conducive to the recovery and reuse of the catalyst.

[0015] The second object of the present invention is achieved in this way: a method for synthesizing dimethyl dicarbonate, characterized in that the method is as follows: the catalyst, solvent and methyl chloroformate are added into a reaction vessel and mixed uniformly, alkali solution is added dropwise at a temperature below 15°C, strong stirring is maintained during the dropping process, phase separation is performed after the dropping is completed, the organic phase is washed with concentrated sulfuric acid and / or phosphoric acid, and dimethyl dicarbonate can be obtained by phase separation. The preparation process is simple and the conversion rate of methyl chloroformate is high. The yield can reach more than 86%.

[0016] In the above scheme, the solvent is one of benzene and toluene, the amount of the catalyst added is 1%-2% of the mass of methyl chloroformate, the alkali solution is sodium hydroxide solution or potassium hydroxide solution, and the mass concentration of the alkali solution is 10-30%. n (methyl chloroformate): n (sodium hydroxide) = 1-1.4:1.

[0017] The third object of the present invention is achieved as follows: A production system of dimethyl dicarbonate, characterized in that it includes an alkali liquid feeding system, an organic phase feeding system, a reaction system, an extraction system, a catalyst recovery system, a toluene distillation system, and a product distillation system;

[0018] The reaction system comprises a reactor, wherein an alkali liquid inlet is arranged at the top of the reactor, the alkali liquid inlet is connected to the alkali liquid feeding system, a reaction liquid outlet pipeline is also arranged at the top of the reactor and is connected to a phase separator, a reflux pipeline is arranged at the middle of the reactor and is connected to a forced circulation heat exchanger, an inlet pipeline of the forced circulation heat exchanger is connected to a forced circulation pump and an organic phase feeding system, and the forced circulation pump is connected to a circulation pipeline at the bottom of the reactor; the reaction temperature in the reactor is controlled at 0-15°C;

[0019] The organic phase feeding system is composed 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. The methyl chloroformate barrel is connected to the oil phase mixing kettle through the methyl chloroformate pump, the oil phase feeding pump is connected to the discharge pipeline of the oil phase mixing kettle, the outlet pipeline of the oil phase feeding pump is connected to a forced circulation heat exchanger, the toluene collecting tank and the toluene charging barrel are respectively connected to the toluene feeding pump through pipelines, the toluene feeding pump is connected to the oil phase mixing kettle, the catalyst recovery pipeline of the catalyst recovery phase separator is connected to the oil phase mixing kettle, the methyl chloroformate concentration of the feed is about 30-70%, and the catalyst concentration is 0.01-0.5%;

[0020] The upper oil phase of the phase separator enters the extraction system, and the lower water phase enters the catalyst recovery system;

[0021] The catalyst recovery system includes a neutralization kettle and a catalyst recovery phase separator; the lower water phase of the phase separator enters the neutralization kettle, where it is neutralized with the acid solution from the extraction system, and the neutralization temperature is 30-40°C; the upper oil phase of the neutralization kettle enters the catalyst recovery separator, and the lower water layer is treated as wastewater;

[0022] 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. The upper acid inlet of the first-stage extraction tower is connected to the first concentrated sulfuric acid or phosphoric acid storage tank, and the upper acid inlet of the second-stage extraction tower is connected to the second concentrated sulfuric acid or phosphoric acid storage tank. The organic phase separated from the upper layer of the phase separator is extracted in turn by the two-stage extraction towers to remove the extractant and water in the organic phase. The mass concentration of sulfuric acid is 60-85%, and the mass concentration of phosphoric acid is 65-85%. The crude product solution of the second-stage extraction tower enters a toluene distillation system, and the crude product from the toluene distillation system enters a crude product distillation system.

[0023] In the above scheme: the alkali liquid feeding system consists of an alkali liquid storage tank, an alkali liquid feeding pump, and an alkali liquid feeding heat exchanger; the alkali liquid storage tank is connected to the alkali liquid feeding pump, the outlet pipeline of the alkali liquid feeding pump is connected to the alkali liquid feeding heat exchanger, and the discharge pipeline of the alkali liquid feeding heat exchanger is connected to the reactor; the sodium hydroxide solution enters the reactor after being cooled by the alkali liquid feeding heat exchanger, the feeding temperature is 0-10°C, and the alkali liquid mass concentration is 10-30%.

[0024] In the above scheme: the toluene distillation system consists of a toluene reboiler, a toluene distillation tower, a toluene distillation tower circulating pump, a toluene condenser, and a toluene collecting tank; the crude product solution of the secondary extraction tower enters the toluene distillation tower from the middle of the toluene distillation tower through the toluene reboiler, the top outlet pipeline of the toluene distillation tower is connected to the toluene condenser, the toluene condenser is connected to the toluene collecting tank, the bottom of the toluene distillation tower is provided with an outlet pipeline connected to the toluene reboiler inlet pipeline through the toluene distillation tower circulating pump, and the outlet pipeline of the toluene distillation tower circulating pump is also connected to the top inlet pipeline of the product distillation tower.

[0025] In the above scheme: the product distillation system is composed of a product distillation tower, a tower top condenser, a tower top secondary condenser, a product condenser, a vacuum buffer tank, a product distillation tower circulation pump, a product distillation tower reboiler, a secondary evaporator, a gas-liquid separator, a heavy component collection tank, and a product collection tank. The tower top pipeline of the product distillation tower is connected to the tower top condenser, the tower top secondary condenser and the vacuum buffer tank in sequence. The vacuum buffer tank is connected to the vacuum system. The product outlet pipeline is arranged at the middle and lower part of the side wall of the product distillation tower and is connected to the product condenser. The outlet pipeline of the product condenser is divided into Two branch pipes, one of which is connected to the product collection tank, and the other is connected to the reflux pipeline at the upper part of the product distillation tower. The bottom outlet pipeline of the product distillation tower is connected to the product distillation tower circulation pump, and the outlet pipeline of the product distillation tower circulation pump is connected to the product distillation tower reboiler and the secondary evaporator at the same time. The outlet of the product distillation tower reboiler is connected to the reflux pipeline at the middle and lower part of the product distillation tower, and the outlet pipeline of the secondary evaporator is connected to the gas-liquid separator. The liquid phase of the gas-liquid separator enters the heavy component collection tank, and the gas phase returns to the product distillation tower from the upper part of the product distillation tower.

[0026] The present invention can realize the continuous production of dimethyl dicarbonate through this system, and realize the recycling of catalyst through the extraction and neutralization system. The water phase separated from the reaction liquid is cleverly used to neutralize the water phase separated from the extraction tower, thereby reducing material consumption. During product distillation, part of the kettle liquid is cleverly transferred to the secondary evaporator, the light component is returned to the product distillation tower, and the heavy component impurities are collected. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a process flow chart of the production system of the present invention.

[0028] Figure 2 The HPLC spectrum of the catalyst of Example 1.

[0029] Figure 3 This is the infrared spectrum of the catalyst of Example 1. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0031] The catalyst of the present invention has the following structure:

[0032] Where R1 is C 12 ~ 16 An alkyl group, preferably R1 is hexadecyl;

[0033] R2 is -((CH2)4O) M -(CH2CH2O) N -H polyglycol, M = 2 to 4, N = 6 to 12;

[0034] R3 may be H, a C1-C5 alkyl group, or the same as R2.

[0035] Example 1

[0036] The catalyst used is hexadecyl group in R1, H in R3 and C-((CH2)4O)2-(CH2CH2O)8-H in R2.

[0037] Catalyst synthesis:

[0038] Weigh 39.8g 4-hexadecylaniline, 5.1g sodium hydroxide, and 0.02g [Cp*IrCl2]2 catalyst into a 125ml high-pressure reactor, heat to 150°C, and use a horizontal flow pump to pump 4.8g methanol into the reactor under stirring for 1h. After keeping warm for 2h, add 0.3g methanol and continue to keep warm for 2h. Discharge the material and wash it with 12.2g 50°C hot water 3 times to obtain 41.5g (water-containing) oily substance; dissolve the above oily substance in 74.2g toluene, and then prepare 72g 14% sodium hydroxide solution, take 10.2g of tetrachloropentylerythrin and disperse it in 30g of toluene and transfer it to a four-necked flask and heat it to 70°C. Use a peristaltic pump to pump the oily toluene solution and sodium hydroxide solution into the four-necked flask, keep the temperature at 75°C, add for 3h, and keep warm for 30min; take out the material, wash with water, separate the phases, separate the organic phase through a column (basic alumina column, 150 mesh, toluene as eluent, elution rate 2mL / min), collect 150-300mL of intermediate B eluent; then add 0.5g of boron trifluoride etherate, 8.5g of dibutyl glycol, 20.5g of polyethylene glycol (PEG400) and 35g of toluene into the reflux reactor, reflux at 115°C for 2h, then add the intermediate B eluent and reflux for 5h. After the reaction is completed, cool to 50°C, add 60g of hot water, stir rapidly for 10min, let stand for 20min and then separate into three layers. Quickly separate the upper and lower liquids, collect the middle liquid and distill under reduced pressure to obtain 65.2g of slightly yellow paste catalyst.

[0039] Using high performance liquid chromatography analysis (chromatographic column: 250 mm × 4.6 mm (id) stainless steel column, filled with InertSustain C18 filler, particle size 5 μm (or a chromatographic column with equivalent column efficiency); mobile phase: ψ (acetonitrile: water) = 30:70, water is adjusted to pH 2.5 with phosphoric acid, filtered through a filter membrane, and degassed in an ultrasonic cleaner for 20 minutes; flow rate (mL / min): 1.0; column temperature: room temperature (temperature difference should not exceed 2°C)) the content is about 67%.

[0040] Figure 2This is the infrared spectrum of the catalyst. In the figure, the broad peak with wave numbers between 3100 and 3600 is the stretching vibration peak of the OH bond, and the hydroxyl broad peak is split, which may indicate the existence of hydroxyl groups with different structures; the wave numbers 2966.56 and 2922.10 are the stretching vibration peaks of -CH3, and the wave number 2852.19 is the stretching vibration peak of -CH2-; the wave numbers 1646.23, 1585.22, 1499.62, and 1460.65 are characteristic peaks of the benzene ring; the wave numbers 1014.42 and 1100.67 are the CO bond vibration peaks, 1014.42 may be the stretching vibration peak of the -CO-ether bond, and 1100.67 may be the stretching vibration peak of the tertiary alcohol -CO-. Through the raw materials and infrared spectra used in the examples, it can be determined that the main structure of the catalyst of the present invention already exists, R1 is hexadecyl, R3 is H, and R2 is C-((CH2)4O)2-(CH2CH2O)8-H.

[0041] Its application method is:

[0042] 1.2g catalyst, 35g toluene and 65g (0.68mol) methyl chloroformate are mixed, then 176g12% (0.528mol) sodium hydroxide solution is splashed therein, control temperature is less than 15 ℃ during dropping, dropping time 20min, and the dropping process keeps strong stirring, and promptly carries out phase separation after dripping.Organic phase uses 1g 85% concentrated sulfuric acid and 2g 75% phosphoric acid to wash 1 time respectively, and phase separation can obtain the mixed solution containing dimethyl dicarbonate, methyl chloroformate, toluene.Obtain dimethyl dicarbonate 40.9g through rectifying, content 99.8%, yield 88.9%.

[0043] Example 2

[0044] The catalyst R1 used is hexadecyl, and R2 and R3 are C-((CH2)4O)2-(CH2CH2O)8-H.

[0045] Catalyst synthesis:

[0046] Weigh 39.8g 4-hexadecylaniline, 5.1g sodium hydroxide, and 0.02g [Cp*IrCl2]2 catalyst into a 125ml high-pressure reactor, heat to 150°C, and use a horizontal flow pump to pump 4.8g methanol into the reactor under stirring for 1h. After keeping warm for 2h, add 0.3g methanol and continue to keep warm for 2h. Discharge the material and wash it with 12.2g 50°C hot water 3 times to obtain 41.5g (water-containing) oily substance; dissolve the above oily substance in 74.2g toluene, and then prepare 72g 14% sodium hydroxide solution, take 10.2g of tetrachloropentylerythrin and disperse it in 30g of toluene and transfer it to a four-necked flask and heat it to 70°C. Use a peristaltic pump to pump the oily toluene solution and sodium hydroxide solution into the four-necked flask, keep the temperature at 75°C, add for 3h, and keep warm for 30min; take out the material, wash with water and separate the phases, separate the organic phase through a column (basic alumina column, 150 mesh, toluene as eluent, elution rate 2mL / min), collect the 150~ 300mL intermediate B eluate; transfer the eluate to a four-necked flask, add 0.5g boron trifluoride etherate, 16.8g dibutyl glycol, reflux at 115℃ for 2h, then add 41.3g polyethylene glycol (PEG400), reflux for 5h, cool to 50℃ after the reaction, add 60g hot water, stir rapidly for 10min, stand for 20min, separate the upper and lower layers of liquid rapidly, collect the middle liquid, and distill under reduced pressure to obtain 92.2g of a slightly yellow paste catalyst. The content is about 78% (the rest are impurities with similar structures).

[0047] Its application method is:

[0048] 1.2g catalyst, 35g toluene and 65g methyl chloroformate are mixed, 212g10% sodium hydroxide (0.53mol) solution is dripped therein, and the temperature is controlled to be lower than 15 ℃ in the dropping process, and the dropping time is 20min. The dropping process keeps strong stirring, and phase separation is carried out after dripping. The organic phase is washed once with 1g 85% concentrated sulfuric acid and 2g 75% phosphoric acid respectively, and phase separation can obtain a mixed solution containing dimethyl dicarbonate, methyl chloroformate and toluene. Rectification obtains 43.3g dimethyl dicarbonate, content 99.9%, yield 94%.

[0049] Example 3

[0050] The catalyst R1 is hexadecyl, R2 and R3 are C-((CH2)4O)2-(CH2CH2O) 12 -H.

[0051] Catalyst synthesis:

[0052] According to the synthesis method of Example 2, the intermediate B eluate was obtained; the intermediate B eluate was transferred to a four-necked flask, 2.5g of concentrated sulfuric acid (98%) and 16.8g of dibutyl glycol were added, refluxed at 115°C for 2h, and then 62.1g of polyethylene glycol (PEG600) was added and refluxed for 5h. After the reaction was completed, it was cooled to 50°C, 60g of hot water was added, and the mixture was stirred rapidly for 10min. After standing for 20min, the upper and lower layers of liquid were separated rapidly, and the middle liquid was collected and distilled under reduced pressure to obtain 92.2g of a slightly yellow paste catalyst. The content was about 76% (the rest were impurities with similar structures).

[0053] Its application method is:

[0054] 1.2g catalyst, 35g toluene and 65g methyl chloroformate are mixed uniformly, and then 74g30% sodium hydroxide (0.55mol) solution is dripped therein, and the temperature is controlled to be lower than 15 ℃ during dripping, and the dropping time is 20min. The dropping process keeps strong stirring, and phase separation is carried out after dripping. The organic phase is washed once with 1g 85% concentrated sulfuric acid and 2g 75% phosphoric acid respectively, and phase separation can obtain a mixed solution containing dimethyl dicarbonate, methyl chloroformate and toluene. Rectification obtains 39.4g of dimethyl dicarbonate, with a content of 99.8% and a yield of 85.5%.

[0055] Example 4

[0056] The catalyst used is hexadecyl group for R1, butyl group for R3, and C-((CH2)4O)4-(CH2CH2O)6-H for R2.

[0057] Catalyst synthesis:

[0058] The intermediate B eluate was prepared according to the steps of Example 1; the intermediate B eluate was transferred to a four-necked flask, 0.5 g of boron trifluoride etherate and 4.8 g of n-butanol were added, and the mixture was refluxed at 115°C for 2 h, 16.5 g of dibutyl glycol was added, and the mixture was refluxed at 115°C for 3 h, and then 15.5 g of polyethylene glycol (PEG300) was added and refluxed for 5 h. After the reaction was completed, the mixture was cooled to 50°C, 60 g of hot water was added, and the mixture was rapidly stirred for 10 min. After standing for 20 min, the upper and lower layers of liquid were rapidly separated, and the middle liquid was collected and distilled under reduced pressure to obtain 51.6 g of a slightly yellow paste catalyst with a content of about 61% (the rest were impurities of similar structure).

[0059] Its application method is:

[0060] 1.2g catalyst, 35g toluene and 65g methyl chloroformate were mixed evenly, and then 74g 30% sodium hydroxide solution was added dropwise thereto. The temperature was controlled to be lower than 15°C during the addition, and the addition time was 20min. Strong stirring was maintained during the addition process, and phase separation was performed after the addition was completed. The organic phase was washed once with 1g 85% concentrated sulfuric acid and 2g 75% phosphoric acid, respectively, and a mixed solution containing dimethyl dicarbonate, methyl chloroformate and toluene was obtained by phase separation. 38.5g dimethyl dicarbonate was obtained by distillation, with a content of 99.8% and a yield of 83.5%.

[0061] Example 5

[0062] The catalyst R1 used is hexadecyl, R 3、 R2 is C-((CH2)4O)4-(CH2CH2O)6-H.

[0063] Catalyst synthesis:

[0064] Prepare intermediate B according to the steps of Example 1; then slowly add 34.2g of dibutylene glycol dropwise into 31.5g of polyethylene glycol (PEG300, using 100ml of toluene with water), reflux at 115°C for 2h, then add the intermediate B eluent and reflux for 5h. After the reaction is completed, cool to 50°C, add 60g of hot water, stir rapidly for 10min, let stand for 20min, quickly separate the upper and lower liquid layers, collect the middle liquid and distill under reduced pressure to obtain 87.6g of light yellow paste catalyst with a content of about 68.5% (the rest are impurities with similar structures).

[0065] Its application method is:

[0066] 1.2g catalyst, 35g toluene and 65g methyl chloroformate were mixed evenly, and 212g 10% sodium hydroxide solution was added dropwise thereto. The temperature was controlled to be lower than 15°C during the dropping process, and the dropping time was 20min. Strong stirring was maintained during the dropping process, and phase separation was performed after the dropping was completed. The organic phase was washed once with 1g 85% concentrated sulfuric acid and 2g 75% phosphoric acid, respectively, and phase separation was performed to obtain a mixed solution containing dimethyl dicarbonate, methyl chloroformate and toluene. 39.1g dimethyl dicarbonate was obtained by distillation, with a content of 99.8% and a yield of 85%.

[0067] Example 6

[0068] The catalyst used is hexadecyl group in R1, H in R3 and C-((CH2)4O)2-(CH2CH2O)8-H in R2.

[0069] 0.65g catalyst, 35g toluene and 65g methyl chloroformate were mixed uniformly, and then 176g 12% sodium hydroxide solution was added dropwise thereto. The temperature was controlled to be less than 15°C during the addition, and the dropping time was 20min. Strong stirring was maintained during the dropping process, and phase separation was performed after the dropwise addition. The organic phase was washed once with 1g 85% concentrated sulfuric acid and 2g 75% phosphoric acid, respectively, and phase separation was performed to obtain a mixed solution containing dimethyl dicarbonate, methyl chloroformate and toluene. 40.1g of dimethyl dicarbonate was obtained through rectification, with a content of 99.8% and a yield of 87.1%.

[0070] Example 7

[0071] The catalyst used is hexadecyl group in R1, H in R3 and C-((CH2)4O)2-(CH2CH2O)8-H in R2.

[0072] 1.35g catalyst, 35g toluene and 65g methyl chloroformate are mixed uniformly, and then 176g 12% sodium hydroxide solution is dripped therein, and the temperature is controlled to be less than 15 ℃ during dripping, and the dripping time is 20min. The dripping process keeps strong stirring, and phase separation is carried out after dripping. The organic phase is washed once with 1g 85% concentrated sulfuric acid and 2g 75% phosphoric acid respectively, and phase separation can obtain a mixed solution containing dimethyl dicarbonate, methyl chloroformate and toluene. 40.5g of dimethyl dicarbonate is obtained through rectification, with a content of 99.8% and a yield of 88.1%.

[0073] Example 8

[0074] The catalyst used is hexadecyl group in R1, H in R3 and C-((CH2)4O)2-(CH2CH2O)8-H in R2.

[0075] 1.35g catalyst, 35g benzene and 65g methyl chloroformate were mixed uniformly, and then 176g 12% sodium hydroxide solution was added dropwise thereto. The temperature was controlled to be less than 15°C during the addition, and the dropping time was 20min. Strong stirring was maintained during the dropping process, and phase separation was performed after the dropwise addition. The organic phase was washed once with 1g 85% concentrated sulfuric acid and 2g 75% phosphoric acid, respectively, and phase separation was performed to obtain a mixed solution containing dimethyl dicarbonate, methyl chloroformate and toluene. 39.8g of dimethyl dicarbonate was obtained through rectification, with a content of 99.8% and a yield of 86.7%.

[0076] Example 9

[0077] The catalyst R1 is hexadecyl, R2 and R3 are C-((CH2)4O)2-(CH2CH2O) 12 -H.

[0078] 1.2g catalyst, 35g toluene and 65g methyl chloroformate are mixed uniformly, and then 102g30% potassium hydroxide (0.55mol) solution is dripped therein, and the temperature is controlled to be lower than 15 ℃ during dripping, and the dropping time is 20min. The dropping process keeps strong stirring, and phase separation is carried out after dripping. The organic phase is washed once with 1g 85% concentrated sulfuric acid and 2g 75% phosphoric acid respectively, and phase separation can obtain a mixed solution containing dimethyl dicarbonate, methyl chloroformate and toluene. Rectification obtains 38.2g of dimethyl dicarbonate, with a content of 99.8% and a yield of 82.8%.

[0079] Example 10

[0080] like Figure 1 As shown, the production system of dimethyl dicarbonate includes an alkali solution feeding system, an organic phase feeding system, a reaction system, an extraction system, a catalyst recovery system, a toluene distillation system, and a product distillation system.

[0081] The reaction system includes a reactor 4, the upper part of which is provided with an alkali liquid inlet, which is connected to an alkali liquid feeding system, which is composed of an alkali liquid storage tank 1, an alkali liquid feeding pump 2, and an alkali liquid feeding heat exchanger 3; the alkali liquid storage tank 1 is connected to the alkali liquid feeding pump 2, the outlet pipeline of the alkali liquid feeding pump 2 is connected to the alkali liquid feeding heat exchanger 3, and the discharge pipeline of the alkali liquid feeding heat exchanger 3 is connected to the reactor 4. The sodium hydroxide solution enters the reactor after being cooled by the alkali liquid feeding heat exchanger, the feeding temperature is 0-10°C, and the mass concentration of the alkali liquid solution is 10-30%. The alkali liquid is a sodium hydroxide or potassium hydroxide solution.

[0082] The upper part of the reactor 4 is also provided with a reaction liquid outlet pipeline connected to the phase separator 10, the middle part of the reactor 4 is provided with a reflux pipeline connected to the forced circulation heat exchanger 6, the inlet pipeline of the forced circulation heat exchanger 6 is connected to the forced circulation pump 5 and the organic phase feeding system, and the forced circulation pump 5 is connected to the circulation pipeline at the bottom of the reactor 4. The reaction temperature in the reactor is controlled at 0-15°C.

[0083] The organic phase feeding system is composed 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. The methyl chloroformate barrel 32 is connected to the oil phase mixing kettle 8 through the methyl chloroformate pump 7, the oil phase feeding pump 9 is connected to the discharge pipeline of the oil phase mixing kettle 8, the outlet pipeline of the oil phase feeding pump 9 is connected to the forced circulation heat exchanger 6, the toluene collecting tank 20 and the toluene charging barrel 33 are respectively connected to the toluene feeding pump 21 through pipelines, the toluene feeding pump 21 is connected to the oil phase mixing kettle 8, the catalyst recovery pipeline of the catalyst recovery phase separator 16 is connected to the oil phase mixing kettle 8, the methyl chloroformate concentration of the feed is about 30-70%, and the catalyst concentration is 0.01-0.5%;

[0084] The upper oil phase of the phase separator 10 enters the extraction system, and the lower water phase enters the catalyst recovery system.

[0085] The catalyst recovery system includes a neutralization kettle 15 and a catalyst recovery phase separator 16; the lower water phase of the phase separator 10 enters the neutralization kettle 15, and is neutralized with the acid solution from the extraction system in the neutralization kettle 15, and the neutralization temperature is 30-40°C; the upper oil phase of the neutralization kettle 15 enters the catalyst recovery separator 16, and the lower water layer is treated as wastewater.

[0086] 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 primary extraction tower 13, and a secondary extraction tower 14. The upper acid inlet of the primary extraction tower 13 is connected to the sulfuric acid storage tank 11, and the upper acid inlet of the secondary extraction tower 14 is connected to the second concentrated sulfuric acid or phosphoric acid storage tank 12. The organic phase separated from the upper layer of the phase separator is extracted by the two-stage extraction towers in sequence to remove the extractant and water in the organic phase. The first concentrated sulfuric acid or phosphoric acid storage tank 11 and the second concentrated sulfuric acid or phosphoric acid storage tank 12 can all contain phosphoric acid, or both contain sulfuric acid, or one sulfuric acid and one phosphoric acid, the mass concentration of sulfuric acid is 60-85%, and the mass concentration of phosphoric acid is 65-85%. The crude product solution of the secondary extraction tower 1 enters the toluene distillation system. The crude product from the toluene distillation system enters the crude product distillation system.

[0087] The toluene distillation system consists of a toluene reboiler 17, a toluene distillation tower 18, a toluene distillation 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 distillation tower 18 from the middle of the toluene distillation tower 18 through the toluene reboiler 17, the top outlet pipeline of the toluene distillation tower 18 is connected to the toluene condenser 34, the toluene condenser 34 is connected to the toluene collecting tank, the bottom of the toluene distillation tower is provided with an outlet pipeline connected to the inlet pipeline of the toluene reboiler 17 through the toluene distillation tower circulating pump 19, and the outlet pipeline of the toluene distillation tower circulating pump 19 is also connected to the top inlet pipeline of the product distillation tower 22.

[0088] The product distillation system consists of a product distillation tower 22, a top condenser 23, a top secondary condenser 24, a product condenser 25, a vacuum buffer tank 35, a product distillation tower circulation pump 26, a product distillation tower reboiler 27, a secondary evaporator 28, a gas-liquid separator 29, a heavy component collection tank 30, and a product collection tank 31. The top pipeline of the product distillation tower is connected to the top condenser 23, the top secondary condenser 24 and the vacuum buffer tank 35 in sequence, and the vacuum buffer tank 35 is connected to the vacuum system. A product outlet pipeline is provided in the middle and lower part of the side wall of the product distillation tower 22 and is connected to the product condenser 25. The outlet pipe of the product condenser 25 The line is divided into two branches, one of which is connected to the product collection tank 31, and the other is connected to the reflux line at the upper part of the product distillation tower. The bottom outlet pipeline of the product distillation tower 27 is connected to the product distillation tower circulation pump 26, and the outlet pipeline of the product distillation tower circulation pump 26 is connected to the product distillation tower reboiler 27 and the secondary evaporator 28 at the same time. The outlet of the product distillation tower reboiler 27 is connected to the reflux line at the middle and lower part of the product distillation tower, and the outlet pipeline of the secondary evaporator 28 is connected to the gas-liquid separator 29. The liquid phase of the gas-liquid separator 29 enters the heavy component collection tank 30, and the gas phase returns to the product distillation tower from the upper part of the product distillation tower.

[0089] The cold material is fed from the top of the tower, and the circulating evaporation is realized through the circulating pump and the reboiler. The gas phase is collected through the product condenser 25 in the middle of the distillation tower to obtain the product. Part of the material is diverted from the product distillation tower circulating pump 26 and enters the secondary evaporator 28 for re-gasification. The heavy components are separated by the gas-liquid separator 29, and the impurities are continuously removed. The impurities are collected by the heavy component collection tank 30.

[0090] In this embodiment: the catalyst R1 used is hexadecyl, R3 is H, and R2 is C-((CH2)4O)2-(CH2CH2O)8-H.

[0091] NaOH with a mass fraction of 15% is pumped into the reaction kettle 4 through the NaOH feed pump 2, and the feed temperature is 5° C.; the mass concentration of methyl chloroformate in the feed is about 65%, and the mass concentration of the catalyst is 0.05%.

[0092] The feed ratio of the organic phase mixture to the NaOH solution is: the molar ratio of methyl chloroformate to NaOH is 1.04:1.

[0093] The reaction temperature was 10°C, the phase separation temperature was 15°C, and the reaction residence time was 30 min.

[0094] The organic phase separated from the upper layer of the phase separator 10 is subjected to two-stage extraction with 75% phosphoric acid in the primary extraction tower 13 and the secondary extraction tower 14. The extracted organic phase enters the toluene distillation system, and the aqueous phase enters the catalyst recovery system. The amount of phosphoric acid used in each stage is 1 kg phosphoric acid / 100 kg methyl chloroformate, the extraction temperature is 30°C, and the residence time is 50 min.

[0095] The acidic aqueous phase coming out of the lower part of the extraction tower and the alkaline aqueous phase at the lower part of the phase separator 10 are neutralized in the neutralization kettle 15 to a pH of 8 and a neutralization temperature of 30°C. The upper oil phase of the neutralization kettle 15 enters the catalyst recovery phase separator 16 for phase separation. The upper layer after phase separation is the recovered catalyst and enters the oil phase mixing kettle 8 for recycling, and the lower layer enters the wastewater treatment.

[0096] After extraction, the organic phase enters the toluene distillation tower 18 for distillation, and the heavy components at the bottom of the tower are pumped into the toluene reboiler 17 through the toluene distillation tower circulation pump 19 for circulation, and part of them are pumped into the product distillation system. The ratio of the circulation flow rate to the entering distillation flow rate is 8:2, the tower bottom temperature is 35°C, and the absolute pressure is 10kpa.

[0097] The product is circulated and evaporated in the product distillation tower 22 through the product distillation tower circulation pump 26 and the product distillation tower reboiler 27. The tower bottom temperature is 30°C, the product condenser 25 temperature is 25°C, the tower top condenser 23 temperature is 18°C, the tower top secondary condenser 24 temperature is 10°C, and the absolute pressure is 0.8 kPa. The circulation pump diverts part of the product to the secondary evaporator 28, the circulation flow ratio and the diversion flow ratio are 8:2, and the temperature of the secondary evaporator 28 is 35°C.

[0098] After the above treatment, dimethyl dicarbonate product can be obtained with a content of 99.8% and a yield of 88.9%.

[0099] Embodiment 11 (steps are the same as 10)

[0100] The catalyst R1 is hexadecyl, R3 is C-((CH2)4O)2-(CH2CH2O)8-H, and R2 is C-((CH2)4O)2-(CH2CH2O)8-H; methyl chloroformate, toluene, and catalyst are pumped into an oil phase mixing kettle (8) at a rate of 65kg / h, 35kg / h, and 1.23kg / h through feed pumps at various locations and mixed evenly;

[0101] A 15% mass fraction NaOH solution was pumped in at a rate of 145 kg / h, and the feed temperature was maintained at about 5°C.

[0102] Reaction: temperature is 10°C, reaction residence time is 30 min.

[0103] Phase separation: phase separation temperature 10℃, phase separation residence time 60min.

[0104] Extraction: (75%) phosphoric acid was extracted twice at a flow rate of 1 kg / h, the extraction temperature was 30°C, and the residence time was 50 min.

[0105] Toluene distillation: bottom temperature is 35°C and absolute pressure is 10kpa.

[0106] Product distillation: tower bottom temperature 30°C, condenser (25) temperature 25°C, condenser (23) temperature 18°C, secondary condenser (24) temperature 10°C, absolute pressure 0.8 kPa. The circulating pump diverts part of the product to the secondary evaporator (28), and the temperature of the secondary evaporator (28) is 35°C.

[0107] After the above treatment, dimethyl dicarbonate product can be produced at a rate of 39.8 kg / h, with a content of 99.8% and a yield of about 90%.

[0108] Example 12

[0109] The catalyst R1 is hexadecyl, and R2 is C-((CH2)4O)4-(CH2CH2O) 13 -H, R3 is C-((CH2)4O)4-(CH2CH2O) 13 -H; 170kg / h of methyl chloroformate and 108kg / h of toluene (including recovery) are pumped into the oil phase mixing kettle (8) through the feed pump, mixed evenly and transferred to the reactor (4); 504.3kg / h of 15% NaOH solution and 2.65kg / h of catalyst are pumped into the reactor (4), and the feed temperature is maintained at about 6°C.

[0110] Reaction: temperature is 10°C, phase separation temperature is 15°C, and reaction residence time is 30 min.

[0111] Extraction: 5kg / h 85% sulfuric acid, 5.5kg / h 75% phosphoric acid, each extraction once, extraction temperature 30°C, residence time 50min.

[0112] Toluene distillation: bottom temperature is 35°C and absolute pressure is 10kpa.

[0113] Product distillation: tower bottom temperature 30°C, condenser (25) temperature 25°C, condenser (23) temperature 18°C, secondary condenser (24) temperature 10°C, absolute pressure 0.8 kPa. The circulating pump diverts part of the product to the secondary evaporator (28), the circulating flow ratio to the diverted flow ratio is 8:2, and the temperature of the secondary evaporator (28) is 35°C.

[0114] After the above treatment, 96 kg of dimethyl dicarbonate product can be obtained per hour, with a content of 99.8% and a yield of about 79%.

[0115] Example 13 (Comparative Example 1)

[0116] The catalyst used was trimethyloctadecylammonium chloride.

[0117] 1.2g catalyst, 50g toluene and 65g methyl chloroformate were mixed evenly, and then 176g 12% sodium hydroxide solution was added dropwise for 20min. Strong stirring was maintained during the addition process, and phase separation was performed after the addition was completed. The organic phase was washed once with 1g 85% concentrated sulfuric acid and 2g 75% phosphoric acid, respectively. Phase separation can obtain a mixed solution containing dimethyl dicarbonate, methyl chloroformate, toluene and methanol. 10.8g dimethyl dicarbonate was obtained by distillation with a theoretical yield of 23.4%.

[0118] Embodiment 14

[0119] The catalyst used was trilaurylamine.

[0120] 1.2g catalyst, 40g toluene and 60g methyl chloroformate were mixed evenly, and then 155g 12% sodium hydroxide solution was added dropwise for 20min. Strong stirring was maintained during the addition process, and phase separation was performed after the addition was completed. The organic phase was washed once with 1g 85% concentrated sulfuric acid and 2g 75% phosphoric acid, respectively. Phase separation can obtain a mixed solution containing dimethyl dicarbonate, methyl chloroformate, toluene and methanol. 21.5g dimethyl dicarbonate was obtained by distillation, and the theoretical yield was 46.6%.

[0121] Embodiment 15

[0122] The rest is the same as Example 9, except that the catalyst used is triisooctylamine.

[0123] 100 kg / h of methyl chloroformate and 67 kg / h of toluene (including recovery) are pumped into the oil phase mixing kettle (8) through a feed pump, mixed evenly, and transferred to the reactor (4); 302.3 kg / h of a 14% by mass NaOH solution and 1.53 kg / h of a catalyst are pumped into the reactor (4), and the feed temperature is maintained at about 6°C.

[0124] Reaction: temperature is 10°C, phase separation temperature is 15°C, and reaction residence time is 30 min.

[0125] Extraction: 5kg / h 85% sulfuric acid, 5.5kg / h 75% phosphoric acid, each extraction once, extraction temperature 30°C, residence time 50min.

[0126] Toluene distillation: bottom temperature is 35°C and absolute pressure is 10kpa.

[0127] Product distillation: tower bottom temperature 30°C, product condenser 25 temperature 25°C, tower top condenser 23 temperature 18°C, tower top secondary condenser 24 temperature 10°C, absolute pressure 0.8 kPa. The product distillation tower circulation pump diverts part of the product to the secondary evaporator 28, the circulation flow ratio and diversion flow ratio is 8:2, and the temperature of the secondary evaporator 28 is 35°C.

[0128] Through the above treatment, 29 kg of dimethyl dicarbonate product can be obtained per hour, with a content of 99.8% and a yield of about 40.9%.

[0129] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Use of a catalyst in the synthesis of dimethyl dicarbonate, characterized in that: The catalyst has the following structure: Where R1 is C 12 ~ 16 The alkyl group; R2 is -((CH2)4O) M -(CH2CH2O) N -H polyglycol, M = 2 to 4, N = 6 to 12; R3 may be H, a C1-C5 alkyl group, or the same as R2.

2. The use according to claim 1, characterized in that: R1 is hexadecyl.

3. The use according to claim 1 or 2, characterized in that: R2 is -((CH2)4O)2-(CH2CH2O)8-H.

4. A method for synthesizing dimethyl dicarbonate, characterized in that: The synthesis is carried out according to the following method: the catalyst, solvent and methyl chloroformate described in any one of claims 1 to 3 are added into a reaction container and mixed evenly, the alkali solution is added dropwise at a temperature below 15° C., strong stirring is maintained during the dropping process, phase separation is carried out after the dropping is completed, the organic phase is washed with concentrated sulfuric acid and / or phosphoric acid, and dimethyl dicarbonate can be obtained by phase separation.

5. The synthetic method of dimethyl dicarbonate according to claim 4, characterized in that: The solvent is one of benzene and toluene, the added amount of the catalyst is 1%-2% of the mass of methyl chloroformate, the alkali solution is sodium hydroxide solution or potassium hydroxide solution, and the mass concentration of the alkali solution is 10-30%.

6. A production system of dimethyl dicarbonate, characterized in that: It includes alkali liquid feeding system, organic phase feeding system, reaction system, extraction system, catalyst recovery system, toluene distillation system and product distillation system; The reaction system comprises a reactor, wherein an alkali liquid inlet is arranged at the top of the reactor, the alkali liquid inlet is connected to the alkali liquid feeding system, a reaction liquid outlet pipeline is also arranged at the top of the reactor and is connected to a phase separator, a reflux pipeline is arranged at the middle of the reactor and is connected to a forced circulation heat exchanger, an inlet pipeline of the forced circulation heat exchanger is connected to a forced circulation pump and an organic phase feeding system, and the forced circulation pump is connected to a circulation pipeline at the bottom of the reactor; the reaction temperature in the reactor is controlled at 0-15°C; The organic phase feeding system is composed 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. The methyl chloroformate barrel is connected to the oil phase mixing kettle through the methyl chloroformate pump, the oil phase feeding pump is connected to the discharge pipeline of the oil phase mixing kettle, the outlet pipeline of the oil phase feeding pump is connected to a forced circulation heat exchanger, the toluene collecting tank and the toluene charging barrel are respectively connected to the toluene feeding pump through pipelines, the toluene feeding pump is connected to the oil phase mixing kettle, the catalyst recovery pipeline of the catalyst recovery phase separator is connected to the oil phase mixing kettle, the methyl chloroformate concentration of the feed is about 30-70%, and the catalyst concentration is 0.01-0.5%; The upper oil phase of the phase separator enters the extraction system, and the lower water phase enters the catalyst recovery system; The catalyst recovery system includes a neutralization kettle and a catalyst recovery phase separator; the lower water phase of the phase separator enters the neutralization kettle, where it is neutralized with the acid solution from the extraction system, and the neutralization temperature is 30-40°C; the upper oil phase of the neutralization kettle enters the 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. The upper acid inlet of the first-stage extraction tower is connected to the first concentrated sulfuric acid or phosphoric acid storage tank, and the upper acid inlet of the second-stage extraction tower is connected to the second concentrated sulfuric acid or phosphoric acid storage tank. The organic phase separated from the upper layer of the phase separator is extracted in turn by the two-stage extraction towers to remove the extractant and water in the organic phase. The mass concentration of sulfuric acid is 60-85%, and the mass concentration of phosphoric acid is 65-85%. The crude product solution of the second-stage extraction tower enters a toluene distillation system, and the crude product from the toluene distillation system enters a crude product distillation system.

7. The production system of dimethyl dicarbonate according to claim 6, characterized in that: The alkali liquid feeding system consists of an alkali liquid storage tank, an alkali liquid feeding pump, and an alkali liquid feeding heat exchanger; the alkali liquid storage tank is connected to the alkali liquid feeding pump, the outlet pipeline of the alkali liquid feeding pump is connected to the alkali liquid feeding heat exchanger, and the discharge pipeline of the alkali liquid feeding heat exchanger is connected to the reactor; the sodium hydroxide solution enters the reactor after being cooled by the alkali liquid feeding heat exchanger, the feeding temperature is 0-10°C, and the mass concentration of the alkali liquid is 10-30%.

8. The production system of dimethyl dicarbonate according to claim 7, characterized in that: The toluene distillation system consists of a toluene reboiler, a toluene distillation tower, a toluene distillation tower circulation pump, a toluene condenser, and a toluene collecting tank; the crude product solution of the secondary extraction tower enters the toluene distillation tower from the middle of the toluene distillation tower through the toluene reboiler, the top outlet pipeline of the toluene distillation tower is connected to the toluene condenser, the toluene condenser is connected to the toluene collecting tank, the bottom of the toluene distillation tower is provided with an outlet pipeline connected to the toluene reboiler inlet pipeline through the toluene distillation tower circulation pump, and the outlet pipeline of the toluene distillation tower circulation pump is also connected to the top inlet pipeline of the product distillation tower.

9. The production system of dimethyl dicarbonate according to claim 7, characterized in that: The product distillation system is composed of a product distillation tower, a tower top condenser, a tower top secondary condenser, a product condenser, a vacuum buffer tank, a product distillation tower circulation pump, a product distillation tower reboiler, a secondary evaporator, a gas-liquid separator, a heavy component collection tank, and a product collection tank. The tower top pipeline of the product distillation tower is connected to the tower top condenser, the tower top secondary condenser and the vacuum buffer tank in sequence. The vacuum buffer tank is connected to the vacuum system. A product outlet pipeline is arranged at the middle and lower part of the side wall of the product distillation tower and is connected to the product condenser. The outlet pipeline of the product condenser is divided into two branches. Pipes, one of which is connected to the product collecting tank, and the other is connected to the reflux pipeline at the upper part of the product distillation tower, the bottom outlet pipeline of the product distillation tower is connected to the product distillation tower circulation pump, the outlet pipeline of the product distillation tower circulation pump is connected to the product distillation tower reboiler and the secondary evaporator at the same time, the outlet of the product distillation tower reboiler is connected to the reflux pipeline at the middle and lower part of the product distillation tower, the outlet pipeline of the secondary evaporator is connected to the gas-liquid separator, the liquid phase of the gas-liquid separator enters the heavy component collecting tank, and the gas phase returns to the product distillation tower from the upper part of the product distillation tower.

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