Preparation method of squaric acid capable of recovering catalyst

Abstract

The invention discloses a preparation method of squaric acid capable of recovering a catalyst, which comprises the following steps: mixing perchloro-1, 3-butadiene, morpholine and an alkaline substance, heating to 85-120 DEG C, reacting for 5-60 hours, filtering after the reaction is finished, and taking filtrate to obtain a first intermediate product; mixing the first intermediate product with a first solid acid catalyst in an organic solvent, stirring and reacting at 25-100 DEG C for 4-24 hours, filtering and recovering the first solid acid catalyst, and carrying out reduced pressure distillation on filtrate to remove the organic solvent, so as to obtain a second intermediate product; mixing the second intermediate product with a second solid acid catalyst and water, reacting at 110 DEG C for 10-24 hours, cooling, filtering and taking filter residues to obtain a squaric acid crude product and second solid acid catalyst mixture; and re-dissolving the squaric acid crude product and the second solid acid catalyst mixture in water, filtering and recovering the solid acid, decolorizing the filtrate with activated carbon, filtering, and recrystallizing to obtain squaric acid. According to the method, the squaric acid yield is increased, and the production management cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical engineering, and in particular relates to a method for preparing squaric acid with a recoverable catalyst. Background Art

[0002] Squaric acid (3,4-dihydroxy-3-cyclobutene-1,2-dione), also known as squaric acid or squaric acid, is an important intermediate for the synthesis of medicines, pesticides, photosensitive materials and dyes. At present, the mainstream preparation method of squaric acid is still the same as many years ago. For example, 1,3-butadiene and morpholine are used as raw materials, and then squaric acid is prepared in toluene (solvent), HOAc-NaOAc buffer solution and 98% sulfuric acid (catalyst) in turn. However, the preparation process has high requirements for reaction temperature, many side reactions, and it is difficult to improve the yield. In addition, the cost remains high. Specifically, (1) the amount of morpholine used is extremely large, and the production cost is high; (2) concentrated sulfuric acid is a hazardous chemical with high management cost; (3) the amount of buffer solution used is large, and the cost of the reaction device is high; (4) the waste acid and waste liquid generated by the buffer solution and concentrated sulfuric acid are large, and the treatment cost is high. It can be seen that the existing preparation process of squaric acid still has many problems. However, more research is currently focusing on the downstream products of squaric acid, while ignoring the improvement of the preparation process of squaric acid itself. Therefore, it is necessary to propose a new preparation method to solve the above problems. Summary of the invention

[0003] In order to solve the above technical problems, the purpose of the present invention is to provide a method for preparing squaric acid with recoverable catalyst, thereby improving the yield and reducing the production management cost.

[0004] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing squaric acid with recoverable catalyst comprises the following steps:

[0006] (1) mixing perchloro-1,3-butadiene, morpholine and an alkaline substance or mixing perchloro-1,3-butadiene, morpholine and an alkaline substance in an organic solvent, heating to 85 to 120° C. for reaction for 5 to 60 hours, filtering after the reaction, washing and collecting the filtrate to obtain a first intermediate product, wherein the alkalinity of the alkaline substance is stronger than that of morpholine;

[0007] (2) mixing the first intermediate product and the first solid acid catalyst in an organic solvent, adding water, stirring and reacting at 25 to 100° C. for 4 to 24 hours, filtering and recovering the first solid acid catalyst, and distilling the obtained filtrate under reduced pressure to remove the organic solvent to obtain a second intermediate product, wherein the first solid acid catalyst is insoluble in water or organic matter;

[0008] (3) mixing the second intermediate product with the second solid acid catalyst and water, reflux stirring, reacting at 80-110° C. for 10-24 hours, cooling, filtering and collecting the residue to obtain a mixture of the crude square acid and the second solid acid catalyst, wherein the second solid acid catalyst is insoluble in water or organic matter;

[0009] (4) The crude squaric acid and the second solid acid catalyst mixture are redissolved in water, the second solid acid catalyst is recovered by filtration, and the filtrate is decolorized by activated carbon, filtered, and recrystallized to obtain squaric acid.

[0010] The first solid acid catalyst in step (2) and the second solid acid catalyst in step (3) may be the same or different. Preferably, in the present invention, the type of the first solid acid catalyst is different from the type of the second solid acid catalyst. More preferably, the first solid acid catalyst is a weakly acidic solid acid catalyst and the second solid acid catalyst is a strongly acidic solid acid catalyst.

[0011] Preferably, in step (1), after the perchloro-1,3-butadiene, morpholine and alkaline substance are mixed, the temperature is first raised to 40-60° C. for reaction, and then the temperature is raised to 85-120° C. for reaction.

[0012] Preferably, in step (1), the molar ratio of morpholine to perchloro-1,3-butadiene is (3-6):1.

[0013] Preferably, in step (1), perchloro-1,3-butadiene and morpholine react to generate hydrogen chloride, and the amount of the alkaline substance input is greater than or equal to the amount of the alkaline substance required to consume the hydrogen chloride.

[0014] Preferably, in step (2), the molar ratio of the added water to the perchloro-1,3-butadiene is greater than or equal to 1, that is, based on 1 mol of perchloro-1,3-butadiene, the water added in step (2) is greater than or equal to 18 g.

[0015] Preferably, in step (3), the molar ratio of the added water to the perchloro-1,3-butadiene is greater than or equal to 10, that is, based on 1 mol of perchloro-1,3-butadiene, the water added in step (3) is greater than or equal to 180 g.

[0016] Preferably, the alkaline substance includes one or more of alkaline inorganic salts, alkaline oxides, inorganic bases or organic Lewis bases without active hydrogen.

[0017] Preferably, the first solid acid catalyst includes one or more of silicate substances, silicon oxide substances, aluminum oxide, titanium dioxide, acidic cationic resin, supported solid acid, and the like.

[0018] Preferably, the second solid acid catalyst includes one or more of phosphotungstic acid, a supported phosphotungstic acid catalyst, a supported phosphomolybdic acid catalyst, an acidic cationic resin, a solid superacid, and the like.

[0019] Preferably, the organic solvent includes one or more of aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, ether solvents, ester solvents, halogenated hydrocarbon solvents, alcohol solvents, ketone solvents or diol derivative solvents.

[0020] Preferably, the organic solvent in step (1) is the same as or different from the organic solvent in step (2); when the organic solvent in step (1) is different from the organic solvent in step (2), after the reaction in step (1) is completed, the organic solvent is first removed by vacuum distillation and then filtered, and after filtering, the filter residue is washed with the organic solvent in step (2).

[0021] Beneficial effects:

[0022] The invention adopts an alkaline substance to consume hydrogen chloride generated by the reaction, thereby avoiding consumption of morpholine, a high-cost raw material, and reducing the raw material cost. In the subsequent reaction, the first solid acid catalyst and the second solid acid catalyst are adopted to effectively reduce the generation of waste liquid and waste acid, and greatly reduce the production management cost. The yield of the square acid of the invention is improved, while the production cost is significantly reduced, which is conducive to the development of square acid-related industries. DETAILED DESCRIPTION

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific implementation methods of the present invention will be described below. Obviously, the following descriptions are only some embodiments of the present invention, and for those of ordinary skill in the art, other implementation methods can also be obtained based on these embodiments without creative work.

[0024] The present invention provides a method for preparing squaric acid with a recoverable catalyst, comprising the following steps:

[0025] (1) mixing perchloro-1,3-butadiene, morpholine and an alkaline substance or mixing perchloro-1,3-butadiene, morpholine and an alkaline substance in an organic solvent, heating to 85 to 120° C. for reaction for 5 to 60 hours, filtering after the reaction, washing and collecting the filtrate to obtain a first intermediate product, wherein the alkalinity of the alkaline substance is stronger than that of morpholine;

[0026] (2) mixing the first intermediate product and the first solid acid catalyst in an organic solvent, adding water, stirring and reacting at 25 to 100° C. for 4 to 24 hours, filtering and recovering the first solid acid catalyst, and distilling the obtained filtrate under reduced pressure to remove the organic solvent to obtain a second intermediate product;

[0027] (3) mixing the second intermediate product with the second solid acid catalyst and water, reflux stirring, reacting at 80-110° C. for 10-24 hours, cooling, filtering and collecting the residue to obtain a mixture of the crude square acid and the second solid acid catalyst;

[0028] (4) The crude squaric acid and the second solid acid catalyst mixture are redissolved in water, the second solid acid catalyst is recovered by filtration, and the filtrate is decolorized by activated carbon, filtered, and recrystallized to obtain squaric acid.

[0029] The reaction mechanism of the present invention is as follows:

[0030]

[0031] The three chlorines in perchloro-1,3-butadiene are replaced by morpholine to generate perchloro-1,3-butadiene substituted product, which is the first intermediate product. At the same time, three molecules of hydrogen chloride are generated, which are consumed by the alkaline substance.

[0032] The first intermediate product is mixed with the first solid acid catalyst and cyclized at 25 to 100° C. to obtain a second intermediate product;

[0033] The second intermediate product is mixed with a second solid acid catalyst, and the second solid acid catalyst is used as a catalyst at 80-110° C. to obtain square acid.

[0034] In step (1), three chlorines in perchloro-1,3-butadiene are replaced by morpholine to generate hydrogen chloride, which is consumed by an additional alkaline substance. In the traditional preparation process, hydrogen chloride needs to be consumed by additional morpholine to generate morpholine hydrochloride, so the consumption of morpholine is extremely large, while in the present invention, the generated hydrogen chloride is consumed by the alkaline substance, avoiding the consumption of morpholine, a key raw material. Compared with the existing process, the amount of morpholine used in the present invention is greatly reduced, and the production cost is reduced.

[0035] Preferably, in step (1), the reaction time may be 6 to 60 hours, and the reaction temperature may be 85 to 110°C.

[0036] Preferably, in step (1), based on perchloro-1,3-butadiene, the molar ratio of morpholine to perchloro-1,3-butadiene is (3-6):1. For example, when perchloro-1,3-butadiene is 1 mol, the amount of morpholine can be 3 mol, 3.1 mol, 3.2 mol, 3.3 mol, 3.4 mol, 3.5 mol, 3.6 mol, 3.7 mol, 3.8 mol, 3.9 mol, 4.0 mol, 4.1 mol, 4.2 mol, 4.3 mol. ol, 4.4mol, 4.5mol, 4.6mol, 4.7mol, 4.8mol, 4.9mol, 5.0mol, 5.1mol, 5.2mol, 5.3mol, 5.4mol, 5.5mol, 5.6mol, 5.7mol, 5.8mol, 5.9mol, 6.0mol, more preferably, the molar ratio of morpholine to perchloro-1,3-butadiene is (3-4):1, and morpholine is slightly excessive to ensure complete reaction of perchloro-1,3-butadiene.

[0037] The role of the alkaline substance is to consume the generated hydrogen chloride. Its alkalinity needs to be stronger than morpholine, otherwise morpholine hydrochloride will be generated first, resulting in insufficient morpholine required for the substitution reaction and incomplete reaction of perchloro-1,3-butadiene. Alkaline substances include alkaline inorganic salts, alkaline oxides, inorganic bases or organic Lewis bases without active hydrogen. If the organic Lewis base contains active hydrogen, it will react with perchloro-1,3-butadiene.

[0038] For example, the alkaline inorganic salt can be a strong base and weak acid salt, such as carbonate, bicarbonate, metal sulfide, hypochlorite, etc. Preferably, the alkaline inorganic salt can be sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium sulfide, potassium sulfide, etc. The alkaline inorganic salt reacts with hydrogen chloride to generate salt and gas and / or water. The salt exists in the reaction system in a solid form, which is convenient for subsequent separation. The generated gas leaves the reaction system. If water is generated, the water can be removed in the subsequent reduced pressure distillation.

[0039] The alkaline oxide can be sodium oxide, potassium oxide, magnesium oxide, calcium oxide, etc. The alkaline oxide reacts with hydrogen chloride to generate salt and water. The salt exists in the reaction system in a solid form, which is convenient for subsequent separation. The water is removed in the subsequent reduced pressure distillation.

[0040] The inorganic base can be potassium hydroxide, sodium hydroxide, etc. The inorganic base reacts with hydrogen chloride to generate salt and water. The salt exists in the reaction system in a solid form, which is convenient for subsequent separation. The water is removed in the subsequent reduced pressure distillation.

[0041] In the present invention, the organic Lewis base containing no active hydrogen can be triethylamine, 1.8-diazabicyclo[5.4.0]undecene-7, 1,4-diazabicyclo[2.2.2]octane, etc. Similar to other types of alkaline substances, the organic Lewis base selected in the present invention reacts with hydrogen chloride, and the generated organic hydrochloride is also present in the system in a solid form, which is convenient for subsequent filtration and separation. The organic Lewis base can be mixed with perchloroprene and morpholine, and the excess organic Lewis base is also evaporated in the reduced pressure distillation of step (2) and removed from the reaction system.

[0042] Due to space limitations, the present invention lists some examples of alkaline substances. It is easy to understand that the alkaline substances of the present invention should not be limited to the above-mentioned substances. In the present invention, any alkaline substance that meets the following conditions can be applied to the present invention: the alkalinity is stronger than morpholine; it does not react with perchloro-1,3-butadiene, morpholine, and organic solvents; it does not decompose at the reaction temperature; the hydrochloride generated by the reaction with hydrogen chloride exists in the reaction system in a solid form; and the liquid alkaline substance can be removed by reduced pressure distillation in step (2).

[0043] Taking the alkaline substance as sodium carbonate as an example, in step (1), sodium carbonate reacts with hydrogen chloride to generate sodium chloride, carbon dioxide and water. Since perchloro-1,3-butadiene and morpholine are both organic substances, sodium carbonate and sodium chloride cannot be dissolved and can only exist in solid form. Carbon dioxide evaporates and leaves the reaction system, and water is miscible with the raw materials. The filtering operation of step (1) separates sodium chloride and the remaining unreacted sodium carbonate from the first intermediate product, and the generated water is removed by reduced pressure distillation in step (2).

[0044] Taking the alkaline substance as triethylamine as an example, in step (1), liquid triethylamine is miscible with the reaction raw material, triethylamine reacts with hydrogen chloride to generate triethylamine hydrochloride, and triethylamine hydrochloride exists in the system in a solid form. The triethylamine hydrochloride can be separated from the first intermediate product by filtering operation, and the excess triethylamine is removed by reduced pressure distillation in step (2). The triethylamine hydrochloride generated by the present invention has a high purity and can be sold as a product, further improving the economic benefit.

[0045] It should be noted that if a liquid alkaline substance, such as triethylamine, is added in step (1), the present invention can also be carried out normally and with better effect by adopting a reaction temperature slightly higher than the boiling point of triethylamine (such as 100-120° C.) under the condition of reflux stirring reaction. Triethylamine does not decompose within the reaction temperature range of the present invention.

[0046] The amount of alkaline substance input is also related to perchloro-1,3-butadiene. In step (1), perchloro-1,3-butadiene reacts with morpholine to generate hydrogen chloride. One molecule of perchloro-1,3-butadiene can generate three molecules of hydrogen chloride. The amount of alkaline substance input is greater than or equal to the amount of alkaline substance required to consume hydrogen chloride. Preferably, the amount of alkaline substance input is equal to the amount of alkaline substance required to consume hydrogen chloride.

[0047] Preferably, based on perchloro-1,3-butadiene, the molar ratio of the alkaline substance to perchloro-1,3-butadiene is (0-4):1, wherein the amount of the alkaline substance is not zero. For example, 1 mol of perchloro-1,3-butadiene generates 3 mol of hydrogen chloride. When 1 mol of alkaline substance can completely react with 1 mol of hydrogen chloride, the molar ratio of alkaline substance to perchloro-1,3-butadiene is (3-4):1 based on perchloro-1,3-butadiene, and the alkaline substance is slightly excessive to ensure that the hydrogen chloride is completely consumed; when 1 mol of alkaline substance can completely react with 2 mol of hydrogen chloride, the molar ratio of alkaline substance to perchloro-1,3-butadiene is (1.5-2):1 based on perchloro-1,3-butadiene; when 1 mol of alkaline substance can completely react with 3 mol of hydrogen chloride, the molar ratio of alkaline substance to perchloro-1,3-butadiene is (1-1.5):1 based on perchloro-1,3-butadiene.

[0048] In step (1), perchloro-1,3-butadiene, morpholine and alkaline substances can be directly mixed for reaction, or reacted in an organic solvent. Specifically, when the raw materials are not reacted in an organic solvent, the temperature can be first raised to 40-60° C. for reaction, and then raised to 85-120° C. for reaction to reduce side reactions. Alternatively, when the raw materials are reacted in an organic solvent, the temperature can be directly raised to 85-120° C. for reaction. It is easy to understand that when the raw materials are mixed with an organic solvent for reaction, the temperature can also be first raised to 40-60° C., and then raised to 85-120° C. for reaction.

[0049] When an organic solvent is added in step (1), the organic solvents in steps (1) and (2) may be the same or different. In step (1), the organic solvent does not react with the raw materials and does not decompose at the reaction temperature.

[0050] In step (1), when an organic solvent is used to mix the raw materials, after the reaction is completed, the organic solvent is mixed with the first intermediate product and other substances. The organic solvent can be evaporated before filtering, and then the filtering operation is performed. The same or different organic solvent is used to wash the filter residue. The organic solvent for washing the filter residue will enter step (2). The organic solvent for washing the filter residue is the same as the organic solvent in step (2).

[0051] It is easy to understand that in step (1), if the organic solvent used in the reaction is the same as the organic solvent used to wash the filter residue after filtration, the operation of distilling out the organic solvent in step (1) can be omitted. If they are different, the former organic solvent is distilled out and then the latter organic solvent is used.

[0052] In the present invention, the organic solvent cannot dissolve morpholine hydrochloride, and the organic solvent includes aromatic hydrocarbon solvents (such as benzene, toluene, xylene, etc.), aliphatic hydrocarbon solvents (pentane, hexane, octane, etc.), alicyclic hydrocarbon solvents (cyclohexane, cyclohexanone, toluene cyclohexanone, etc.), ether solvents (ethyl ether, propylene oxide, etc.), ester solvents (methyl acetate, ethyl acetate, propyl acetate, etc.), glycol derivative solvents (ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, etc.), halogenated hydrocarbon solvents (chlorobenzene, dichlorobenzene, dichloromethane, etc.), alcohol solvents (methanol, ethanol, isopropanol, etc.), ketone solvents (acetone, methyl butyl ketone, methyl isobutyl ketone, etc.) or other solvents (acetonitrile, pyridine, phenol, etc.).

[0053] Preferably, when the raw materials are mixed with an organic solvent in step (1), the organic solvent is an aromatic hydrocarbon solvent, an aliphatic hydrocarbon solvent, an alicyclic hydrocarbon solvent, an ether solvent, an ester solvent or a diol derivative solvent.

[0054] More preferably, the organic solvent of the present invention is an aromatic hydrocarbon solvent or an ester solvent, such as toluene, ethyl acetate, propyl acetate, butyl acetate, etc. It is easy to understand that when the organic solvent is an ester solvent, such as butyl acetate, under alkaline conditions, the ester organic matter may be partially hydrolyzed, but in the present invention, no water is added as a raw material in step (1), and water is generated by the reaction of alkaline substances and hydrogen chloride, and the alkaline substances have been consumed, so the effect on the ester solvent is small and can be ignored. In the subsequent step (2), although water is added, the reaction system is not conducive to the decomposition of ester substances, and the effect on the ester solvent can also be ignored.

[0055] In step (1), the reaction temperature and the reaction time are in a negatively correlated relationship, that is, when the reaction temperature is higher, the reaction time is generally shorter to avoid more side reactions. For example, when the final reaction temperature is 85°C, the reaction time is close to 60h. It is easy to understand that the choice of reaction temperature is also related to the properties of the alkaline substance, and the decomposition of the alkaline substance should be avoided under the conditions of the reaction temperature.

[0056] After the filtration operation in step (1), it is generally necessary to clean the filter residue so that the first intermediate product attached to the filter residue enters the filtrate. The cleaning operation uses an organic solvent, and the organic solvent is mixed with the first intermediate product and enters step (2). In step (2), the same organic solvent is added again to immerse the first solid acid catalyst, which is convenient for the subsequent stirring reaction.

[0057] In step (2), during the conversion of the first intermediate product to the second intermediate product, morpholine will be produced, and the first solid acid catalyst will not only play a catalytic role, but also play a role in consuming morpholine, thereby increasing the yield of the second intermediate product. The first solid acid catalyst is insoluble in an organic solvent, which is convenient for subsequent separation and reuse, reduces processing costs, and also greatly reduces the generation of waste liquid and waste acid. It should be noted that the salt generated by the reaction of the first solid acid catalyst with morpholine can be regenerated by soaking it in hydrochloric acid to form the first solid acid catalyst, or, it can be roasted and regenerated to form the first solid acid catalyst.

[0058] In step (2), as long as the first solid acid catalyst meets the following conditions, it is applicable to the present invention: the first solid acid catalyst is a weakly acidic solid acid catalyst; it has a catalytic effect on the reaction of converting the first intermediate product into the second intermediate product; it does not dissolve in the reaction system and remains in a solid state; and it can react with morpholine to remove morpholine.

[0059] Preferably, the first solid acid catalyst includes one or more of silicate substances, silicon oxide substances, alumina, titanium dioxide, acidic cationic resins, supported solid acids, etc., wherein silicate substances include zeolite, silica-alumina molecular sieve, ZSM-5, KL molecular sieve, diatomaceous earth, kaolin, activated clay, attapulgite, bentonite, montmorillonite, hydroxyapatite, etc.; silicon oxide substances include multi-level porous silica, silica gel, pure silicon molecular sieve, SBA-15, ZSM-5, MCM-41, etc.; supported solid acids include weakly acidic supported phosphotungstic acid catalysts, HF / Al2O3, HCl / silica gel, H2SO4 / silica gel, H2SO4 / diatomaceous earth, etc. It should be noted that HF / Al2O3, HCl / silica gel, H2SO4 / silica gel, H2SO4 / diatomaceous earth are formed by mixing acid with a carrier.

[0060] It should be noted that the amount of the first solid acid catalyst is related to the amount of morpholine produced. The first solid acid catalyst consumes morpholine and plays a catalytic role. Therefore, the amount of the first solid acid catalyst is greater than the amount of morpholine produced in step (2). Preferably, based on 1 mol of perchloro-1,3-butadiene, the amount of the first solid acid catalyst used is greater than or equal to 210g.

[0061] In step (2), the operation of reduced pressure distillation can not only evaporate the organic solvent, but also remove the alkaline substances in the liquid remaining in step (1) and the water produced in step (1).

[0062] It should be noted that water needs to be added as a reaction substance in step (2), and the molar ratio of the added water to perchloro-1,3-butadiene is greater than or equal to 1, that is, based on 1 mol of perchloro-1,3-butadiene, the water added in step (2) is greater than or equal to 1 mol (i.e., greater than or equal to 18 g). Excess water in step (2) is removed by distillation under reduced pressure.

[0063] In step (3), the second solid acid catalyst is insoluble in water or organic matter, and mainly plays a catalytic role to improve the yield of square acid. Preferably, the second solid acid catalyst is a strongly acidic solid acid catalyst. In this step, morpholine hydrochloride is produced during the conversion of the second intermediate product into square acid. The morpholine hydrochloride is soluble in water and insoluble in the organic phase of the reaction system. The morpholine hydrochloride can be removed in the subsequent filtering operation.

[0064] Water also needs to be added in step (3). The purpose of adding water is different from that in step (2). In step (3), water not only participates in the reaction but also serves as a solvent for removing morpholine hydrochloride. Therefore, more water needs to be added. Specifically, based on perchloro-1,3-butadiene, the molar ratio of water participating in the reaction in step (3) to perchloro-1,3-butadiene is greater than or equal to 3, that is, when 1 mol of perchloro-1,3-butadiene is used as the raw material, at least 3 mol (i.e., 54 g) of water needs to be added in step (3) as a reactant; and more water is needed to dissolve morpholine hydrochloride in step (3). Based on 1 mol of perchloro-1,3-butadiene, the morpholine hydrochloride generated in step (3) needs at least 125 g (about 7 mol) of water to dissolve. Therefore, in step (3), the molar ratio of water added to perchloro-1,3-butadiene is greater than or equal to 10. If based on 1 mol of perchloro-1,3-butadiene, the water added in step (3) is greater than or equal to 180 g.

[0065] Preferably, the second solid acid catalyst includes one or more of phosphotungstic acid, supported phosphotungstic acid catalyst, supported phosphomolybdic acid catalyst, acidic cationic resin, solid superacid, etc., wherein the supported phosphotungstic acid catalyst includes phosphotungstic acid modified SBA-15, phosphotungstic acid modified MCM-41, silicotungstic acid modified SBA-15, etc.; the solid superacid includes SO4 2- / TiO2、SO4 2- / ZrO2、SO4 2- / Fe2O3、SO4 2- / Al2O3, etc.; supported phosphomolybdic acid catalysts include phosphomolybdic acid modified MCM-41, etc. More preferably, based on 1 mol of perchloro-1,3-butadiene, the amount of the second solid acid catalyst used is greater than or equal to 12.8 g.

[0066] The solubility of square acid at room temperature is very low, and the solubility is only 20g / L under the condition of 30°C. In step (3), the generated square acid mainly exists in the form of solid and is mixed with the second solid acid catalyst. It is easy to understand that since the amount of square acid dissolved in water at room temperature is very small, and the filtrate of step (3) also contains morpholine hydrochloride, it will be time-consuming and labor-intensive to recover the square acid in the aqueous solution. Therefore, the present invention mainly purifies the square acid from the filter residue of step (3). In step (4), the square acid crude product and the second solid acid catalyst mixture are redissolved in a large amount of water. Since the second solid acid catalyst is insoluble in water, and the square acid is soluble in water, the separation of square acid and the second solid acid catalyst is achieved, and the second solid acid catalyst is recovered and can be reused. The square acid solution is decolorized with activated carbon and then refined by recrystallization to obtain square acid.

[0067] The technical solution of the present invention is described in detail below with specific embodiments.

[0068] Example 1

[0069] 1 mol of perchloro-1,3-butadiene, 3 mol of morpholine and 3 mol of triethylamine were mixed in 400 ml of butyl acetate, the temperature was raised to 110° C., the reaction was performed for 7 hours, and after the reaction was completed, the mixture was filtered, and the filtrate was a solution of the first intermediate product;

[0070] The solution of the first intermediate product was mixed with 210 g of the first solid acid catalyst (multi-level porous silica), 20 mL of water was added, and solvent butyl acetate was added to immerse the first solid acid catalyst, and the mixture was stirred at 60° C. for 10 h, filtered to obtain a filtrate, and then the mixture including butyl acetate was distilled off under reduced pressure to obtain a second intermediate product;

[0071] The second intermediate product was mixed with 12.8 g of the second solid acid catalyst (phosphotungstic acid-modified SBA-15), 282 mL of water was added, refluxed with stirring, reacted at 100° C. for 12 h, and then filtered to precipitate a mixture of the second solid acid catalyst and square acid;

[0072] The mixture was redissolved in water and filtered to obtain a filtrate. The filtrate was decolorized with activated carbon and then filtered. After recrystallization, 90 g of white granular square acid was obtained with a yield of 78.95%.

[0073] Example 2

[0074] 1 mol of perchloro-1,3-butadiene, 3 mol of morpholine and 3 mol of triethylamine were mixed in 400 ml of propyl acetate, the temperature was raised to 100° C., and the reaction was performed for 20 hours. After the reaction was completed, the mixture was filtered, and the filtrate was a solution of the first intermediate product;

[0075] The solution of the first intermediate product was mixed with 210 g of the first solid acid catalyst (hierarchical porous silica), 20 mL of water was added, and solvent propyl acetate was added to immerse the first solid acid catalyst, and the mixture was stirred at 60° C. for 12 h, filtered to obtain a filtrate, and then the mixture including propyl acetate was distilled off under reduced pressure to obtain a second intermediate product;

[0076] The second intermediate product was mixed with 12.8 g of the second solid acid catalyst (phosphotungstic acid-modified SBA-15), 282 mL of water was added, refluxed with stirring, reacted at 100° C. for 12 h, and then filtered to precipitate a mixture of the second solid acid catalyst and square acid;

[0077] The crude product of square acid and the crude product of the second solid acid catalyst mixture were redissolved in water and filtered to obtain a filtrate, the filtrate was decolorized with activated carbon and then filtered, and white granular crystals were obtained after recrystallization; the mother liquor was concentrated and cooled to precipitate a white solid, the white granular crystals and the white solid were refined to obtain square acid to obtain 91g square acid, and the yield was 79.82%.

[0078] Example 3

[0079] 1 mol of perchloro-1,3-butadiene, 3 mol of morpholine and 3 mol of triethylamine were mixed in 400 ml of ethyl acetate, the temperature was raised to 85° C., the reaction was performed for 60 hours, and after the reaction was completed, the filtrate was filtered, and the filtrate was a solution of the first intermediate product;

[0080] The solution of the first intermediate product was mixed with 210 g of the first solid acid catalyst (multi-level porous silica), 20 mL of water was added, and solvent ethyl acetate was added to immerse the first solid acid catalyst, and the mixture was stirred at 60° C. for 12 h, filtered to obtain a filtrate, and then the mixture such as ethyl acetate was distilled off under reduced pressure to obtain a second intermediate product;

[0081] The second intermediate product was mixed with 12.8 g of the second solid acid catalyst (phosphotungstic acid-modified SBA-15), 282 mL of water was added, refluxed with stirring, reacted at 100° C. for 12 h, and then filtered to precipitate a mixture of the second solid acid catalyst and square acid;

[0082] The crude product of square acid and the crude product of the second solid acid catalyst mixture were redissolved in water and filtered to obtain a filtrate, the filtrate was decolorized with activated carbon and then filtered, and white granular crystals were obtained after recrystallization; the mother liquor was concentrated and cooled to precipitate a white solid, the white granular crystals and the white solid were refined to obtain square acid to obtain 92g square acid, and the yield was 80.70%.

[0083] Example 4

[0084] 1 mol of perchloro-1,3-butadiene, 3 mol of morpholine and 3 mol of triethylamine were mixed in 400 ml of amyl acetate, the temperature was raised to 120° C., the reaction was performed for 5 hours, and after the reaction was completed, the filtrate was filtered, and the filtrate was a solution of the first intermediate product;

[0085] The solution of the first intermediate product was mixed with 210 g of the first solid acid catalyst (multi-level porous silica), 20 mL of water was added, and solvent amyl acetate was added to immerse the first solid acid catalyst, and the mixture was stirred at 60° C. for 12 h, filtered to obtain a filtrate, and then the mixture including amyl acetate was distilled off under reduced pressure to obtain a second intermediate product;

[0086] The second intermediate product was mixed with 12.8 g of the second solid acid catalyst (phosphotungstic acid-modified SBA-15), 282 mL of water was added, refluxed with stirring, reacted at 100° C. for 12 h, and then filtered to precipitate a mixture of the second solid acid catalyst and square acid;

[0087] The crude product of square acid and the crude product of the second solid acid catalyst mixture were redissolved in water and filtered to obtain a filtrate, the filtrate was decolorized with activated carbon and then filtered, and white granular crystals were obtained after recrystallization; the mother liquor was concentrated and cooled to precipitate a white solid, the white granular crystals and the white solid were refined to obtain square acid to obtain 87g square acid, and the yield was 76.32%.

[0088] Example 5

[0089] 1 mol of perchloro-1,3-butadiene, 3 mol of morpholine and 3.2 mol of triethylamine were mixed in 400 ml of ethylene glycol monobutyl ether, heated to 120° C., reacted for 5 hours, filtered after the reaction was completed, and the filtrate was a solution of the first intermediate product;

[0090] The solution of the first intermediate product was mixed with 210 g of the first solid acid catalyst (multi-level porous silica), 20 mL of water was added, and a solvent of ethylene glycol monobutyl ether was added to immerse the first solid acid catalyst, and the mixture was stirred at 60° C. for 12 h, filtered to obtain a filtrate, and then the mixture of ethylene glycol monobutyl ether and the like was distilled off under reduced pressure to obtain a second intermediate product;

[0091] The second intermediate product was mixed with 12.8 g of the second solid acid catalyst (phosphotungstic acid-modified SBA-15), 282 mL of water was added, refluxed with stirring, reacted at 100° C. for 12 h, and then filtered to precipitate a mixture of the second solid acid catalyst and square acid;

[0092] The crude product of square acid and the crude product of the second solid acid catalyst mixture were redissolved in water and filtered to obtain a filtrate, the filtrate was decolorized with activated carbon and then filtered, and white granular crystals were obtained after recrystallization; the mother liquor was concentrated and cooled to precipitate a white solid, the white granular crystals and the white solid were refined to obtain square acid to obtain 85g square acid, and the yield was 74.56%.

[0093] Example 6

[0094] 1 mol of perchloro-1,3-butadiene, 3 mol of morpholine and 3 mol of triethylamine were mixed in 400 ml of xylene, the temperature was raised to 120° C., the reaction was performed for 5 hours, and after the reaction was completed, the filtrate was filtered, and the filtrate was a solution of the first intermediate product;

[0095] The solution of the first intermediate product was mixed with 420 g of the first solid acid catalyst (multi-level porous silica), 20 mL of water was added, and solvent xylene was added to immerse the first solid acid catalyst, and the mixture was stirred at 60° C. for 12 h, filtered to obtain a filtrate, and then the mixture such as xylene was distilled off under reduced pressure to obtain a second intermediate product;

[0096] The second intermediate product was mixed with 12.8 g of the second solid acid catalyst (phosphotungstic acid-modified SBA-15), 282 mL of water was added, refluxed with stirring, reacted at 110° C. for 12 h, and then filtered to precipitate a mixture of the second solid acid catalyst and square acid;

[0097] The crude product of square acid and the crude product of the second solid acid catalyst mixture were redissolved in water and filtered to obtain a filtrate, the filtrate was decolorized with activated carbon and then filtered, and white granular crystals were obtained after recrystallization; the mother liquor was concentrated and cooled to precipitate a white solid, the white granular crystals and the white solid were refined to obtain square acid to obtain 84g square acid, and the yield was 73.68%.

[0098] Example 7

[0099] 1 mol of perchloro-1,3-butadiene, 3 mol of morpholine and 3 mol of triethylamine were mixed in 400 ml of pyridine, heated to 110° C., reacted for 7 hours, filtered after the reaction was completed, and the filtrate was a solution of the first intermediate product;

[0100] The solution of the first intermediate product was mixed with 210 g of the first solid acid catalyst (multi-level porous silica), 20 mL of water was added, and solvent pyridine was added to immerse the first solid acid catalyst, and the mixture was stirred at 60° C. for 12 h, filtered to obtain a filtrate, and then the mixture including pyridine was distilled off under reduced pressure to obtain a second intermediate product;

[0101] The second intermediate product was mixed with 12.8 g of the second solid acid catalyst (phosphotungstic acid-modified SBA-15), 282 mL of water was added, refluxed and stirred, reacted at 110° C. for 10 h, and then filtered to precipitate a mixture of the second solid acid catalyst and square acid;

[0102] The crude product of square acid and the crude product of the second solid acid catalyst mixture were redissolved in water and filtered to obtain a filtrate, the filtrate was decolorized with activated carbon and then filtered, and white granular crystals were obtained after recrystallization; the mother liquor was concentrated and cooled to precipitate a white solid, the white granular crystals and the white solid were refined to obtain square acid to obtain 90g square acid, and the yield was 78.95%.

[0103] Example 8

[0104] 1 mol of perchloro-1,3-butadiene, 3.5 mol of morpholine and 3 mol of triethylamine were mixed in 400 ml of 1,4-dioxane, the temperature was raised to 100° C., and the reaction was performed for 20 hours. After the reaction was completed, the mixture was filtered, and the filtrate was a solution of the first intermediate product;

[0105] The solution of the first intermediate product was mixed with 210 g of the first solid acid catalyst (multi-level porous silica), 20 mL of water was added, and the solvent 1,4-dioxane was added to immerse the first solid acid catalyst, and the mixture was stirred at 60° C. for 12 h, filtered to obtain a filtrate, and then the mixture of 1,4-dioxane and the like was distilled off under reduced pressure to obtain a second intermediate product;

[0106] The second intermediate product was mixed with 12.8 g of the second solid acid catalyst (phosphotungstic acid-modified SBA-15), 282 mL of water was added, refluxed with stirring, reacted at 90° C. for 20 h, and then filtered to precipitate a mixture of the second solid acid catalyst and square acid;

[0107] The crude product of square acid and the crude product of the second solid acid catalyst mixture were redissolved in water and filtered to obtain a filtrate, the filtrate was decolorized with activated carbon and then filtered, and white granular crystals were obtained after recrystallization; the mother liquor was concentrated and cooled to precipitate a white solid, the white granular crystals and the white solid were refined to obtain square acid to obtain 91g square acid, and the yield was 79.82%.

[0108] Example 9

[0109] 1 mol of perchloro-1,3-butadiene, 3 mol of morpholine and 3 mol of 1.8-diazabicyclo[5.4.0]undecene-7 were mixed in 400 ml of butyl acetate, heated to 110° C., reacted for 7 hours, filtered after the reaction, and the filtrate was a solution of the first intermediate product;

[0110] The solution of the first intermediate product was mixed with 210 g of the first solid acid catalyst (multi-level porous silica), 20 mL of water was added, and solvent butyl acetate was added to immerse the first solid acid catalyst, and the mixture was stirred at 60° C. for 12 h, filtered to obtain a filtrate, and then the mixture including butyl acetate was distilled off under reduced pressure to obtain a second intermediate product;

[0111] The second intermediate product was mixed with 12.8 g of the second solid acid catalyst (phosphotungstic acid-modified SBA-15), 282 mL of water was added, refluxed with stirring, reacted at 100° C. for 12 h, and then filtered to precipitate a mixture of the second solid acid catalyst and square acid;

[0112] The crude product of square acid and the crude product of the second solid acid catalyst mixture were redissolved in water and filtered to obtain a filtrate, the filtrate was decolorized with activated carbon and then filtered, and white granular crystals were obtained after recrystallization; the mother liquor was concentrated and cooled to precipitate a white solid, the white granular crystals and the white solid were refined to obtain square acid to obtain 88g square acid, and the yield was 77.19%.

[0113] Example 10

[0114] 1 mol of perchloro-1,3-butadiene, 3 mol of morpholine and 3 mol of 1,4-diazabicyclo[2.2.2]octane were mixed in 400 ml of butyl acetate, heated to 110° C., reacted for 7 hours, filtered after the reaction was completed, and the filtrate was a solution of the first intermediate product;

[0115] The solution of the first intermediate product was mixed with 210 g of the first solid acid catalyst (multi-level porous silica), 20 mL of water was added, and solvent butyl acetate was added to immerse the first solid acid catalyst, and the mixture was stirred at 60° C. for 12 h, filtered to obtain a filtrate, and then the mixture including butyl acetate was distilled off under reduced pressure to obtain a second intermediate product;

[0116] The second intermediate product was mixed with 12.8 g of the second solid acid catalyst (phosphotungstic acid-modified SBA-15), 282 mL of water was added, refluxed with stirring, reacted at 100° C. for 12 h, and then filtered to precipitate a mixture of the second solid acid catalyst and square acid;

[0117] The crude product of square acid and the crude product of the second solid acid catalyst mixture were redissolved in water and filtered to obtain a filtrate, the filtrate was decolorized with activated carbon and then filtered, and white granular crystals were obtained after recrystallization; the mother liquor was concentrated and cooled to precipitate a white solid, the white granular crystals and the white solid were refined to obtain square acid to obtain 86g square acid, and the yield was 75.44%.

[0118] Embodiment 11

[0119] 1 mol of perchloro-1,3-butadiene, 3 mol of morpholine and 3 mol of sodium carbonate (which can be converted into sodium bicarbonate) are mixed in 400 ml of butyl acetate, heated to 110° C., reacted for 7 hours, filtered after the reaction, and the filtrate is a solution of the first intermediate product;

[0120] The solution of the first intermediate product was mixed with 210 g of the first solid acid catalyst (multi-level porous silica), 20 mL of water was added, and solvent butyl acetate was added to immerse the first solid acid catalyst, and the mixture was stirred at 60° C. for 12 h, filtered to obtain a filtrate, and then the mixture including butyl acetate was distilled off under reduced pressure to obtain a second intermediate product;

[0121] The second intermediate product was mixed with 12.8 g of the second solid acid catalyst (phosphotungstic acid-modified SBA-15), 282 mL of water was added, refluxed with stirring, reacted at 100° C. for 12 h, and then filtered to precipitate a mixture of the second solid acid catalyst and square acid;

[0122] The crude product of square acid and the crude product of the second solid acid catalyst mixture were redissolved in water and filtered to obtain a filtrate, the filtrate was decolorized with activated carbon and then filtered, and white granular crystals were obtained after recrystallization; the mother liquor was concentrated and cooled to precipitate a white solid, the white granular crystals and the white solid were refined to obtain square acid to obtain 78g square acid, and the yield was 68.42%.

[0123] Example 12

[0124] 1 mol of perchloro-1,3-butadiene, 3 mol of morpholine and 3 mol of potassium hydroxide were mixed in 400 ml of butyl acetate, the temperature was raised to 110° C., the reaction was performed for 7 hours, and after the reaction was completed, the mixture was filtered, and the filtrate was a solution of the first intermediate product;

[0125] The solution of the first intermediate product was mixed with 210 g of the first solid acid catalyst (multi-level porous silica), 20 mL of water was added, and solvent butyl acetate was added to immerse the first solid acid catalyst, and the mixture was stirred at 60° C. for 12 h, filtered to obtain a filtrate, and then the mixture including butyl acetate was distilled off under reduced pressure to obtain a second intermediate product;

[0126] The second intermediate product was mixed with 12.8 g of the second solid acid catalyst (phosphotungstic acid-modified SBA-15), 282 mL of water was added, refluxed with stirring, reacted at 100° C. for 12 h, and then filtered to precipitate a mixture of the second solid acid catalyst and square acid;

[0127] The crude product of square acid and the crude product of the second solid acid catalyst mixture were redissolved in water and filtered to obtain a filtrate, the filtrate was decolorized with activated carbon and then filtered, and white granular crystals were obtained after recrystallization; the mother liquor was concentrated and cooled to precipitate a white solid, the white granular crystals and the white solid were refined to obtain square acid to obtain 69g square acid, and the yield was 60.53%.

[0128] Embodiment 13

[0129] 1 mol of perchloro-1,3-butadiene, 3 mol of morpholine and 3 mol of triethylamine were mixed in 400 ml of butyl acetate, the temperature was raised to 120° C., and the reaction was performed for 5 hours. After the reaction was completed, the mixture was filtered, and the filtrate was a solution of the first intermediate product;

[0130] The solution of the first intermediate product was mixed with 420 g of the first solid acid catalyst (silica gel), 20 mL of water was added, and butyl acetate was added to immerse the first solid acid catalyst, and the mixture was stirred at 60° C. for 12 h, filtered to obtain a filtrate, and then butyl acetate and other mixtures were distilled off under reduced pressure to obtain a second intermediate product;

[0131] The second intermediate product was mixed with 12.8 g of the second solid acid catalyst (phosphotungstic acid-modified SBA-15), 282 mL of water was added, refluxed with stirring, reacted at 100° C. for 12 h, and then filtered to precipitate a mixture of the second solid acid catalyst and square acid;

[0132] The crude product of square acid and the crude product of the second solid acid catalyst mixture were redissolved in water and filtered to obtain a filtrate, the filtrate was decolorized with activated carbon and then filtered, and white granular crystals were obtained after recrystallization; the mother liquor was concentrated and cooled to precipitate a white solid, the white granular crystals and the white solid were refined to obtain square acid to obtain 84g square acid, and the yield was 73.68%.

[0133] Embodiment 14

[0134] 1 mol of perchloro-1,3-butadiene, 3 mol of morpholine and 3 mol of triethylamine were mixed in 400 ml of butyl acetate, the temperature was raised to 110° C., the reaction was performed for 7 hours, and after the reaction was completed, the mixture was filtered, and the filtrate was a solution of the first intermediate product;

[0135] The solution of the first intermediate product was mixed with 420 g of the first solid acid catalyst (cation exchange resin), 20 mL of water was added, and solvent butyl acetate was added to immerse the first solid acid catalyst, and the mixture was stirred at 60° C. for 12 h, filtered to obtain a filtrate, and then the mixture including butyl acetate was distilled off under reduced pressure to obtain a second intermediate product;

[0136] The second intermediate product was mixed with 12.8 g of the second solid acid catalyst (phosphotungstic acid-modified SBA-15), 282 mL of water was added, refluxed with stirring, reacted at 100° C. for 12 h, and then filtered to precipitate a mixture of the second solid acid catalyst and square acid;

[0137] The crude product of square acid and the crude product of the second solid acid catalyst mixture were redissolved in water and filtered to obtain a filtrate, the filtrate was decolorized with activated carbon and then filtered, and white granular crystals were obtained after recrystallization; the mother liquor was concentrated and cooled to precipitate a white solid, the white granular crystals and the white solid were refined to obtain square acid to obtain 93g square acid, and the yield was 81.58%.

[0138] Embodiment 15

[0139] 1 mol of perchloro-1,3-butadiene, 3 mol of morpholine and 3 mol of triethylamine were mixed in 400 ml of butyl acetate, the temperature was raised to 110° C., the reaction was performed for 7 hours, and after the reaction was completed, the mixture was filtered, and the filtrate was a solution of the first intermediate product;

[0140] The solution of the first intermediate product was mixed with 210 g of the first solid acid catalyst (multi-level porous silica), 20 mL of water was added, and solvent butyl acetate was added to immerse the first solid acid catalyst, and the mixture was stirred at 25° C. for 24 h, filtered to obtain a filtrate, and then the mixture including butyl acetate was distilled off under reduced pressure to obtain a second intermediate product;

[0141] The second intermediate product was mixed with 12.8 g of the second solid acid catalyst (phosphotungstic acid-modified SBA-15), 282 mL of water was added, refluxed with stirring, reacted at 100° C. for 12 h, and then filtered to precipitate a mixture of the second solid acid catalyst and square acid;

[0142] The crude product of square acid and the crude product of the second solid acid catalyst mixture were redissolved in water and filtered to obtain a filtrate, the filtrate was decolorized with activated carbon and then filtered, and white granular crystals were obtained after recrystallization; the mother liquor was concentrated and cooled to precipitate a white solid, the white granular crystals and the white solid were refined to obtain square acid to obtain 91g square acid, and the yield was 79.82%.

[0143] Example 16

[0144] 1 mol of perchloro-1,3-butadiene, 3 mol of morpholine and 3 mol of triethylamine were mixed in 400 ml of butyl acetate, the temperature was raised to 110° C., the reaction was performed for 7 hours, and after the reaction was completed, the mixture was filtered, and the filtrate was a solution of the first intermediate product;

[0145] The solution of the first intermediate product was mixed with 210 g of the first solid acid catalyst (multi-level porous silica), 20 mL of water was added, and butyl acetate was added to immerse the first solid acid catalyst, and the mixture was stirred at 100° C. for 4 h, filtered to obtain a filtrate, and then butyl acetate and other mixtures were distilled off under reduced pressure to obtain a second intermediate product;

[0146] The second intermediate product was mixed with 12.8 g of the second solid acid catalyst (phosphotungstic acid-modified SBA-15), 282 mL of water was added, refluxed with stirring, reacted at 100° C. for 12 h, and then filtered to precipitate a mixture of the second solid acid catalyst and square acid;

[0147] The crude product of square acid and the crude product of the second solid acid catalyst mixture were redissolved in water and filtered to obtain a filtrate, the filtrate was decolorized with activated carbon and then filtered, and white granular crystals were obtained after recrystallization; the mother liquor was concentrated and cooled to precipitate a white solid, the white granular crystals and the white solid were refined to obtain square acid to obtain 85g square acid, and the yield was 74.56%.

[0148] Embodiment 17

[0149] 1 mol of perchloro-1,3-butadiene, 3 mol of morpholine and 3 mol of triethylamine were mixed in 400 ml of butyl acetate, the temperature was raised to 110° C., the reaction was performed for 7 hours, and after the reaction was completed, the mixture was filtered, and the filtrate was a solution of the first intermediate product;

[0150] The solution of the first intermediate product was mixed with 210 g of the first solid acid catalyst (multi-level porous silica), 20 mL of water was added, and solvent butyl acetate was added to immerse the first solid acid catalyst, and the mixture was stirred at 60° C. for 12 h, filtered to obtain a filtrate, and then the mixture including butyl acetate was distilled off under reduced pressure to obtain a second intermediate product;

[0151] The second intermediate product was mixed with 15 g of the second solid acid catalyst (SBA-15 modified with silicotungstic acid), 282 mL of water was added, refluxed with stirring, reacted at 100° C. for 18 h, and then filtered to precipitate a mixture of the second solid acid catalyst and squaric acid;

[0152] The crude product of square acid and the crude product of the second solid acid catalyst mixture were redissolved in water and filtered to obtain a filtrate, the filtrate was decolorized with activated carbon and then filtered, and white granular crystals were obtained after recrystallization; the mother liquor was concentrated and cooled to precipitate a white solid, the white granular crystals and the white solid were refined to obtain square acid to obtain 90g square acid, and the yield was 78.95%.

[0153] Embodiment 18

[0154] 1 mol of perchloro-1,3-butadiene, 3 mol of morpholine and 3 mol of triethylamine were mixed in 400 ml of butyl acetate, the temperature was raised to 110° C., the reaction was performed for 7 hours, and after the reaction was completed, the mixture was filtered, and the filtrate was a solution of the first intermediate product;

[0155] The solution of the first intermediate product was mixed with 210 g of the first solid acid catalyst (multi-level porous silica), 20 mL of water was added, and solvent butyl acetate was added to immerse the first solid acid catalyst, and the mixture was stirred at 60° C. for 12 h, filtered to obtain a filtrate, and then the mixture including butyl acetate was distilled off under reduced pressure to obtain a second intermediate product;

[0156] The second intermediate product was mixed with 14 g of a second solid acid catalyst (MCM-41 modified with phosphomolybdic acid), 282 mL of water was added, the mixture was refluxed and stirred, reacted at 100° C. for 24 h, and then filtered to precipitate a mixture of the second solid acid catalyst and squaric acid;

[0157] The crude product of square acid and the crude product of the second solid acid catalyst mixture were redissolved in water and filtered to obtain a filtrate, the filtrate was decolorized with activated carbon and then filtered, and white granular crystals were obtained after recrystallization; the mother liquor was concentrated and cooled to precipitate a white solid, the white granular crystals and the white solid were refined to obtain square acid to obtain 90g square acid, and the yield was 78.95%.

[0158] Embodiment 19

[0159] 1 mol of perchloro-1,3-butadiene, 3 mol of morpholine and 3 mol of triethylamine were mixed, the temperature was raised to 100°C, and the reaction was carried out for 16 hours. After the reaction was completed, the temperature was lowered, ethanol was added to dissolve and filtered, and the filtrate was a solution of the first intermediate product;

[0160] The solution of the first intermediate product was mixed with 210 g of the first solid acid catalyst (multi-level porous silica), 20 mL of water was added, and solvent ethanol was added to immerse the first solid acid catalyst, and the mixture was stirred at 60° C. for 10 h, filtered to obtain a filtrate, and then the mixture such as ethanol was distilled off under reduced pressure to obtain a second intermediate product;

[0161] The second intermediate product was mixed with 12.8 g of the second solid acid catalyst (phosphotungstic acid-modified SBA-15), 282 mL of water was added, refluxed with stirring, reacted at 100° C. for 12 h, and then filtered to precipitate a mixture of the second solid acid catalyst and square acid;

[0162] The mixture was redissolved in water and filtered to obtain a filtrate. The filtrate was decolorized with activated carbon and then filtered. After recrystallization, 95 g of white granular square acid was obtained with a yield of 83.33%.

[0163] Comparative Example 1

[0164] This comparative example is an existing process for preparing square acid.

[0165] In a 3L three-necked flask, 178ml (1.15mol) of perchloro-1,3-butadiene, 602ml (6.90mol) of morpholine and 450ml of toluene were placed, and the mixture was refluxed with stirring for 7h to precipitate a large amount of light yellow solid.

[0166] The mixture was cooled to 80°C, 2000 ml of 1 mol / L HOAc-NaOAc buffer solution was added, and the mixture was stirred at 60°C for 16 h. About 1500 ml of a mixture of toluene, morpholine and water was distilled off under reduced pressure.

[0167] Then slowly add 750 ml of 98% sulfuric acid, reflux and stir for 24 hours, let stand overnight, pour out the upper solution to obtain the mother liquor, and filter to obtain a brown crude product.

[0168] The brown crude product was dissolved in water, decolorized by activated carbon, and recrystallized to obtain white granular crystals. The mother liquor was concentrated and cooled to precipitate some white solids, which were purified, combined and dried to obtain 69.7 g of square acid with a yield of 53.2%.

[0169] According to the comparison between Examples 1-19 and Comparative Example 1, in the existing process, a large amount of morpholine is required, which is equivalent to 6 times the amount of perchloro-1,3-butadiene, and a large amount of waste liquid is generated after the buffer solution is added. The reduced pressure distillation in step (2) consumes a large amount of energy. The present invention reduces the amount of morpholine by half and greatly reduces the generation of waste liquid. The first solid acid catalyst and the second solid acid catalyst used in the present invention are present in the reaction system in solid form, which is convenient for separation, recovery and reuse, significantly reducing costs, and significantly improving the yield. It is significantly superior to the existing square acid production process in terms of cost reduction and efficiency improvement.

[0170] The embodiments provided by the present invention are described in detail above. Specific examples are used herein to describe the principles and implementation methods of the present invention, and the description of the above embodiments is only used to help understand the core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a squaric acid with a recoverable catalyst, characterized in that: The following steps are involved: (1) mixing perchloro-1,3-butadiene, morpholine and an alkaline substance or mixing perchloro-1,3-butadiene, morpholine and an alkaline substance in an organic solvent, heating to 85 to 120° C. for reaction for 5 to 60 hours, filtering after the reaction, washing and collecting the filtrate to obtain a first intermediate product, wherein the alkalinity of the alkaline substance is stronger than that of morpholine; (2) mixing the first intermediate product and the first solid acid catalyst in an organic solvent, adding water, stirring and reacting at 25 to 100° C. for 4 to 24 hours, filtering and recovering the first solid acid catalyst, and distilling the obtained filtrate under reduced pressure to remove the organic solvent to obtain a second intermediate product, wherein the first solid acid catalyst is insoluble in water or organic matter; (3) mixing the second intermediate product with the second solid acid catalyst and water, reflux stirring, reacting at 80-110° C. for 10-24 hours, cooling, filtering and collecting the residue to obtain a mixture of the crude square acid and the second solid acid catalyst, wherein the second solid acid catalyst is insoluble in water or organic matter; (4) The crude squaric acid and the second solid acid catalyst mixture are redissolved in water, the second solid acid catalyst is recovered by filtration, and the filtrate is decolorized by activated carbon, filtered, and recrystallized to obtain squaric acid.

2. The preparation method according to claim 1, characterized in that: The first solid acid catalyst is a weakly acidic solid acid catalyst, and the second solid acid catalyst is a strongly acidic solid acid catalyst.

3. The preparation method according to claim 1, characterized in that: In step (1), after perchloro-1,3-butadiene, morpholine and alkaline substances are mixed, the temperature is first raised to 40-60° C. for reaction, and then the temperature is raised to 85-120° C. for reaction.

4. The preparation method according to claim 1, characterized in that: In step (1), the molar ratio of morpholine to perchloro-1,3-butadiene is (3-6):

1.

5. The preparation method according to claim 1, characterized in that: In step (1), perchloro-1,3-butadiene and morpholine react to generate hydrogen chloride, and the amount of the alkaline substance input is greater than or equal to the amount of the alkaline substance required to consume the hydrogen chloride.

6. The preparation method according to claim 1, characterized in that: The alkaline substance includes one or more of alkaline inorganic salts, alkaline oxides, inorganic bases or organic Lewis bases without active hydrogen.

7. The preparation method according to claim 2, characterized in that: The first solid acid catalyst includes one or more of silicate substances, silicon oxide substances, aluminum oxide, titanium dioxide, acidic cationic resin, supported solid acid, and the like.

8. The preparation method according to claim 2, characterized in that: The second solid acid catalyst includes one or more of phosphotungstic acid, a supported phosphotungstic acid catalyst, a supported phosphomolybdic acid catalyst, an acidic cationic resin, a solid superacid, and the like.

9. The preparation method according to claim 1, characterized in that: The organic solvent in step (1) is the same as or different from the organic solvent in step (2); When the organic solvent in step (1) is different from the organic solvent in step (2), after the reaction in step (1) is completed, the organic solvent is first removed by vacuum distillation and then filtered. After filtering, the filter residue is washed with the organic solvent in step (2).

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