CN111470952A - Method for preparing high-purity m-cresol by selectively oxidizing m-p-mixed cresol - Google Patents
Method for preparing high-purity m-cresol by selectively oxidizing m-p-mixed cresol Download PDFInfo
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- RLSSMJSEOOYNOY-UHFFFAOYSA-N m-cresol Chemical compound CC1=CC=CC(O)=C1 RLSSMJSEOOYNOY-UHFFFAOYSA-N 0.000 title claims abstract description 128
- 238000000034 method Methods 0.000 title claims abstract description 20
- 230000001590 oxidative effect Effects 0.000 title claims abstract description 9
- QTWJRLJHJPIABL-UHFFFAOYSA-N 2-methylphenol;3-methylphenol;4-methylphenol Chemical compound CC1=CC=C(O)C=C1.CC1=CC=CC(O)=C1.CC1=CC=CC=C1O QTWJRLJHJPIABL-UHFFFAOYSA-N 0.000 title claims description 18
- 229930003836 cresol Natural products 0.000 title claims description 18
- RGHHSNMVTDWUBI-UHFFFAOYSA-N para-hydroxybenzaldehyde Natural products OC1=CC=C(C=O)C=C1 RGHHSNMVTDWUBI-UHFFFAOYSA-N 0.000 claims abstract description 39
- 238000006243 chemical reaction Methods 0.000 claims abstract description 29
- 239000000203 mixture Substances 0.000 claims abstract description 27
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 24
- 239000003054 catalyst Substances 0.000 claims abstract description 22
- 238000001816 cooling Methods 0.000 claims abstract description 19
- HVLGHSGBNCPKCQ-UHFFFAOYSA-N 4-hydroxybenzaldehyde;sodium Chemical compound [Na].OC1=CC=C(C=O)C=C1 HVLGHSGBNCPKCQ-UHFFFAOYSA-N 0.000 claims abstract description 17
- 239000002904 solvent Substances 0.000 claims abstract description 17
- 239000000047 product Substances 0.000 claims abstract description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 16
- 239000012266 salt solution Substances 0.000 claims abstract description 15
- 238000002425 crystallisation Methods 0.000 claims abstract description 13
- 238000010438 heat treatment Methods 0.000 claims abstract description 13
- 230000008025 crystallization Effects 0.000 claims abstract description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 11
- 239000001301 oxygen Substances 0.000 claims abstract description 11
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 11
- 239000012043 crude product Substances 0.000 claims abstract description 10
- 239000012065 filter cake Substances 0.000 claims abstract description 10
- 238000001914 filtration Methods 0.000 claims abstract description 10
- QOINKMNRLBCJOP-UHFFFAOYSA-M sodium;3-methylphenolate Chemical compound [Na+].CC1=CC=CC([O-])=C1 QOINKMNRLBCJOP-UHFFFAOYSA-M 0.000 claims abstract description 10
- 238000003756 stirring Methods 0.000 claims abstract description 10
- 238000001035 drying Methods 0.000 claims abstract description 5
- 238000003760 magnetic stirring Methods 0.000 claims abstract description 5
- -1 parahydroxyben-zaldehyde sodium salt Chemical class 0.000 claims abstract description 5
- IWDCLRJOBJJRNH-UHFFFAOYSA-N p-cresol Chemical compound CC1=CC=C(O)C=C1 IWDCLRJOBJJRNH-UHFFFAOYSA-N 0.000 claims description 50
- 238000007254 oxidation reaction Methods 0.000 claims description 21
- 230000003647 oxidation Effects 0.000 claims description 19
- 239000012452 mother liquor Substances 0.000 claims description 15
- 238000000926 separation method Methods 0.000 claims description 15
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical group OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 12
- 238000004821 distillation Methods 0.000 claims description 12
- 238000004519 manufacturing process Methods 0.000 claims description 8
- 229940011182 cobalt acetate Drugs 0.000 claims description 7
- QAHREYKOYSIQPH-UHFFFAOYSA-L cobalt(II) acetate Chemical compound [Co+2].CC([O-])=O.CC([O-])=O QAHREYKOYSIQPH-UHFFFAOYSA-L 0.000 claims description 7
- OPQARKPSCNTWTJ-UHFFFAOYSA-L copper(ii) acetate Chemical compound [Cu+2].CC([O-])=O.CC([O-])=O OPQARKPSCNTWTJ-UHFFFAOYSA-L 0.000 claims description 7
- PTVDYARBVCBHSL-UHFFFAOYSA-N copper;hydrate Chemical compound O.[Cu] PTVDYARBVCBHSL-UHFFFAOYSA-N 0.000 claims description 6
- 229940100630 metacresol Drugs 0.000 claims description 5
- 239000000376 reactant Substances 0.000 claims description 4
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 3
- 238000009833 condensation Methods 0.000 claims description 3
- 230000005494 condensation Effects 0.000 claims description 3
- 239000011521 glass Substances 0.000 claims description 3
- 238000007747 plating Methods 0.000 claims description 3
- 229910052709 silver Inorganic materials 0.000 claims description 3
- 239000004332 silver Substances 0.000 claims description 3
- 230000035484 reaction time Effects 0.000 claims description 2
- 238000005485 electric heating Methods 0.000 claims 1
- 238000004321 preservation Methods 0.000 claims 1
- 239000010413 mother solution Substances 0.000 abstract 2
- 230000006837 decompression Effects 0.000 abstract 1
- 230000020477 pH reduction Effects 0.000 abstract 1
- 239000003921 oil Substances 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 239000000178 monomer Substances 0.000 description 3
- PHVAHRJIUQBTHJ-UHFFFAOYSA-N 3-methylphenol;4-methylphenol Chemical compound CC1=CC=C(O)C=C1.CC1=CC=CC(O)=C1 PHVAHRJIUQBTHJ-UHFFFAOYSA-N 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 238000003889 chemical engineering Methods 0.000 description 2
- 239000007810 chemical reaction solvent Substances 0.000 description 2
- 239000000571 coke Substances 0.000 description 2
- 239000010779 crude oil Substances 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 239000012847 fine chemical Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 239000007800 oxidant agent Substances 0.000 description 2
- 239000008247 solid mixture Substances 0.000 description 2
- 230000002194 synthesizing effect Effects 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 239000003905 agrochemical Substances 0.000 description 1
- 230000029936 alkylation Effects 0.000 description 1
- 238000005804 alkylation reaction Methods 0.000 description 1
- 239000003963 antioxidant agent Substances 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000011280 coal tar Substances 0.000 description 1
- 239000002537 cosmetic Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000000796 flavoring agent Substances 0.000 description 1
- 235000019634 flavors Nutrition 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000000543 intermediate Substances 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
- 239000011782 vitamin Substances 0.000 description 1
- 229940088594 vitamin Drugs 0.000 description 1
- 229930003231 vitamin Natural products 0.000 description 1
- 235000013343 vitamin Nutrition 0.000 description 1
- 150000003722 vitamin derivatives Chemical class 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C37/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring
- C07C37/68—Purification; separation; Use of additives, e.g. for stabilisation
- C07C37/685—Processes comprising at least two steps in series
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C37/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring
- C07C37/68—Purification; separation; Use of additives, e.g. for stabilisation
- C07C37/86—Purification; separation; Use of additives, e.g. for stabilisation by treatment giving rise to a chemical modification
Abstract
A method for preparing high-purity m-cresol by selectively oxidizing m-p-cresol mixture comprises the steps of putting the m-p-cresol mixture, a catalyst, sodium hydroxide and a solvent into a container, stirring, heating to a reaction temperature, continuously introducing oxygen for reaction, adding water, distilling to recover the solvent to obtain a mother solution, performing acidification treatment, adjusting pH, cooling for crystallization, and filtering to obtain a filter cake which is p-hydroxybenzaldehyde sodium salt solution, wherein the mother solution is a m-cresol sodium salt solution; dissolving and acidifying parahydroxyben-zaldehyde sodium salt, adjusting pH, cooling, crystallizing, filtering to obtain filter cake as a wet parahydroxyben-zaldehyde product, and drying to obtain a finished parahydroxyben-zaldehyde product with the purity of more than 99.2%; acidifying the m-cresol sodium salt solution, adjusting the pH, collecting an oil-phase m-cresol crude product and putting the oil-phase m-cresol crude product into a tower kettle of a rectifying tower; starting magnetic stirring in the tower kettle for stirring, starting a high-vacuum mechanical pump for decompression, starting the tower kettle for heating and raising the temperature, and collecting front, main and back distillates to obtain a main distillate which is a m-cresol finished product with the purity of more than 99.5 percent.
Description
Technical Field
The invention relates to the field of fine chemical engineering, in particular to a method for preparing high-purity m-cresol by selectively oxidizing m-p-mixed cresol.
Background
The metacresol has two main purposes: organic synthesis and analytical reagents. It is an important raw material for synthesizing cosmetics, antioxidants, agricultural chemicals, etc., and it is used in synthesizing adhesives, synthetic resins, and developers for color films. With the demand for vitamin preparation in the pharmaceutical industry and the development of the flavor industry, the demand for m-cresol, especially m-cresol of high purity, has increased year by year. In the process of separating mixed cresol, because the boiling points of m-cresol and p-cresol only differ by 0.4 ℃ and the melting points differ by 24.6 ℃, the separation and purification of m-cresol and p-cresol are difficult by common distillation or rectification technology. The mixed phenol has limited application, and m-cresol and p-cresol monomers have higher additional values. At present, the production of m-cresol and p-cresol in China is difficult to meet the demand, a large amount of cresol monomers are imported, and if the cresol monomers can be separated by a simple, safe and economic method, the international competitiveness of subsequent products of the substances can be powerfully improved. This requires finding a suitable way to separate them.
The traditional separation process of m-cresol and p-cresol mixture mainly comprises the following steps: azeotropic method, extraction method, adsorption separation method, high-pressure crystallization separation method, complex extraction crystallization method, chelate-like separation method, complex separation method, alkylation method, melt crystallization separation method, and the like. The traditional separation method is difficult to obtain high-purity m-cresol at lower cost.
Chinese patent CN109776276A discloses a method for separating m-cresol and p-cresol mixtures by using selective oxidation catalysts. The method comprises the following steps: 1) oxidation of m-p-cresol mixture: adding the m-cresol-p-cresol mixture, the catalyst and the solvent into a high-pressure reaction kettle, closing the reaction kettle, starting stirring, introducing oxygen or air to a specified pressure, heating to the reaction temperature, and keeping for 2-10 hours. Cooling to room temperature after the reaction is finished, exhausting gas, opening the reaction kettle and collecting mother liquor after the reaction; 2) rectification and separation: carrying out reduced pressure distillation treatment on the mother liquor obtained in the step 1), removing the reaction solvent and water generated in the reaction, recycling the reaction solvent, collecting the residual solid mixture, and adding the solid mixture into a tower kettle of a rectifying tower.
Disclosure of Invention
The invention aims to provide a method for preparing high-purity m-cresol by selectively oxidizing m-p-mixed cresol aiming at the problems in the prior art.
The invention comprises the following steps:
1) and (3) oxidation: placing m-cresol and p-cresol mixture, catalyst, sodium hydroxide and solvent into a container, stirring, heating to a reaction temperature, continuously introducing oxygen for reaction, adding water, and distilling to recover the solvent to obtain mother liquor;
in step 1), the molar ratio of m-cresol to p-cresol in the m-p-mixed cresol may be (50: 1) to (0.01: 1), preferably (2: 1) to (1: 9); the catalyst can be a mixture of cobalt acetate, copper acetate and water, the catalyst components can be cobalt acetate, copper acetate and water in a mass ratio of 4: 1, and the catalyst accounts for 1-4%, preferably 2-3% of the reactants in the mass ratio; the molar ratio of the sodium hydroxide to the m-cresol and p-cresol mixture can be (3-5): 1, preferably (3.5-4): 1; the solvent can be methanol, and the molar ratio of the solvent to the m-cresol and p-cresol mixture can be (10-15): 1, preferably (12-13): 1; the reaction temperature can be 50-70 ℃, and preferably 60-65 ℃; the time of the oxygen reaction can be 4-10 h.
2) And (3) crystallization separation: acidifying the mother liquor obtained in the step 1), adjusting the pH value, cooling to crystallize, cooling to 5-10 ℃, and filtering to obtain a filter cake which is p-hydroxybenzaldehyde sodium salt and mother liquor which is m-cresol sodium salt solution;
in the step 2), the pH value can be 10-11.
3) Post-treatment of p-hydroxybenzaldehyde sodium salt: dissolving and acidifying the p-hydroxybenzaldehyde sodium salt obtained in the step 2), adjusting pH, cooling for crystallization, cooling to 5-10 ℃, filtering to obtain a filter cake which is a wet p-hydroxybenzaldehyde product, and drying to obtain a p-hydroxybenzaldehyde finished product with the purity of more than 99.2%;
in the step 3), the pH value can be 6-7.
4) After-treatment of the meta-cresol sodium salt solution: acidifying the m-cresol sodium salt solution obtained in the step 2), adjusting the pH value, standing for phase splitting, collecting an oil phase m-cresol crude product and putting the oil phase m-cresol crude product into a tower kettle of a rectifying tower; the height of the rectifying tower is 1.5m, the diameter is 2cm, the glass spring is filled, the tower body is insulated by vacuum silver plating, the tower kettle is heated by an electric jacket and stirred by magnetic force, the condenser is cooled by low-temperature water condensation, and the receiving bottle is connected with a high-vacuum mechanical pump. Starting magnetic stirring in the tower kettle for stirring, starting a high-vacuum mechanical pump for pressure reduction, starting the tower kettle for heating when the vacuum degree of the system reaches 100-200 Pa, heating, and gradually collecting front distillation, main distillation and back distillation to obtain the m-cresol finished product with the purity of more than 99.5%.
In the step 4), the pH value can be 6-7.
The invention uses the catalyst of selective oxidation to carry out oxidation treatment on the mixture of m-cresol and p-cresol, the p-cresol in the mixture is completely oxidized into p-hydroxybenzaldehyde, and the m-cresol does not react. After oxidation reaction, because the p-hydroxybenzaldehyde sodium salt is separated by a crystallization mode, the p-hydroxybenzaldehyde sodium salt is dissolved, acidified and filtered to obtain p-hydroxybenzaldehyde, mother liquor is acidified to obtain a m-cresol crude product, and the high-purity m-cresol can be obtained by rectification.
Compared with the prior art, the invention has the following outstanding advantages:
1) the raw material source range of the p-hydroxybenzaldehyde product is expanded: deep processing of the coke and semi-coke coal tar to obtain m-cresol and a byproduct of coal-made natural gas and m-cresol;
2) the raw materials contain 1-99% of p-cresol and 1-99% of m-cresol, which are all applicable to the invention;
3) the purity of the obtained p-hydroxybenzaldehyde is more than 99.2 percent, the purity of the m-cresol is more than 99.5 percent, and the use requirements of fine chemical engineering and medical intermediates are met;
4) the separation method of the invention uses oxygen as oxidant, has mild reaction condition, simple reaction operation and low production cost, and is easy for industrialized production.
Detailed Description
The present invention will be described in detail below with reference to examples, and the scope of the present invention is not limited to the following examples.
The embodiment of the invention comprises the following steps:
1) and (3) oxidation: placing m-cresol and p-cresol mixture, catalyst, sodium hydroxide and solvent into a container, stirring, heating to a reaction temperature, continuously introducing oxygen for reaction, adding water, and distilling to recover the solvent to obtain mother liquor; the molar ratio of cresol to p-cresol in the m-cresol and p-cresol mixture is (50: 1) to (0.01: 1); the catalyst is a mixture of cobalt acetate, copper acetate and water, the catalyst components can be cobalt acetate, copper acetate and water in a mass ratio of 4: 1, and the catalyst accounts for 1-4% of the reactants in the mass ratio; the molar ratio of the using amount of the sodium hydroxide to the m-cresol and p-cresol mixture is (3-5): 1; the solvent can be methanol, and the molar ratio of the using amount of the solvent to the m-p-mixed cresol is (10-15): 1; the reaction temperature is 50-70 ℃; the time of the oxygen reaction is 4-10 h.
2) And (3) crystallization separation: acidifying the mother liquor obtained in the step 1), adjusting the pH value, cooling to crystallize, cooling to 5-10 ℃, and filtering to obtain a filter cake which is p-hydroxybenzaldehyde sodium salt and mother liquor which is m-cresol sodium salt solution; the pH value is 10-11.
3) Post-treatment of p-hydroxybenzaldehyde sodium salt: dissolving and acidifying the p-hydroxybenzaldehyde sodium salt obtained in the step 2), adjusting pH, cooling to crystallize, cooling to 5-10 ℃, filtering to obtain a filter cake which is a wet p-hydroxybenzaldehyde product, and drying to obtain a p-hydroxybenzaldehyde finished product with the purity of more than 99.2%; the pH value is 6-7.
4) After-treatment of the meta-cresol sodium salt solution: acidifying the m-cresol sodium salt solution obtained in the step 2), adjusting the pH value, standing for phase splitting, collecting an oil phase m-cresol crude product and putting the oil phase m-cresol crude product into a tower kettle of a rectifying tower; the height of the rectifying tower is 1.5m, the diameter is 2cm, the glass spring is filled, the tower body is insulated by vacuum silver plating, the tower kettle is heated by an electric jacket and stirred by magnetic force, the condenser is cooled by low-temperature water condensation, and the receiving bottle is connected with a high-vacuum mechanical pump. Starting magnetic stirring in the tower kettle for stirring, starting a high-vacuum mechanical pump for pressure reduction, starting the tower kettle for heating when the vacuum degree of the system reaches 100-200 Pa, heating, and gradually collecting front distillation, main distillation and back distillation to obtain the m-cresol finished product with the purity of more than 99.5%. The pH value is 6-7.
In step 1) of the method for separating m-p-mixed cresol according to the present invention, the catalyst is a mixture of cobalt acetate, copper acetate and water. The addition of a small amount of water makes the selective catalytic effect better, effectively preventing the oxidation of m-cresol. The amount of the catalyst is preferably 2-3% of the weight of the reactants. When the dosage is too small, the catalytic effect is not obvious, and the reaction time is too long; when the amount is too large, the catalyst is wasted, and the cost is increased.
The molar ratio of the intermediate-to-mixed cresol of the step 1) to the p-cresol is preferably (2: 1) to (1: 9). When the content of m-cresol is higher than 70%, the reaction can still be well carried out, the yield of the p-hydroxybenzaldehyde can be greatly reduced, the cost of raw materials is increased, and the method is not suitable for large-scale production.
Specific examples are given below.
Example 1
1) And (3) oxidation: putting m-cresol-p-cresol (1080g, m-cresol: p-cresol: 2: 1, mol ratio), catalyst (2.5 wt%), sodium hydroxide (1500g) and solvent (methanol: 10000ml) into a flask, starting stirring, heating to reaction temperature (65 ℃), continuously introducing oxygen (2000ml/min), and reacting for 8 h. After the reaction, water is added and the solvent is recovered by distillation.
Conversion was determined by gas chromatography using an Agilent 6890N DB-5 quartz capillary column (30m × 0.32.32 mm), hydrogen Flame Ionization Detector (FID).
2) And (3) crystallization separation: acidifying the mother liquor obtained in the step 1), adjusting the pH to 10, cooling to crystallize, cooling to 5 ℃, and filtering to obtain a filter cake which is p-hydroxybenzaldehyde sodium salt and a mother liquor which is m-cresol sodium salt solution.
3) Post-treatment of p-hydroxybenzaldehyde sodium salt: dissolving and acidifying the p-hydroxybenzaldehyde sodium salt obtained in the step 2), adjusting the pH value to 6, cooling for crystallization, cooling to 5 ℃, filtering to obtain a filter cake which is a wet p-hydroxybenzaldehyde product, and drying to obtain 301g of a p-hydroxybenzaldehyde finished product with the purity of 99.7%, wherein the yield of the p-hydroxybenzaldehyde is 80.0%.
4) After-treatment of the meta-cresol sodium salt solution: acidifying the m-cresol sodium salt solution obtained in the step 2), adjusting the pH value to be 6, standing for phase splitting, collecting 800g of crude oil phase m-cresol, putting the crude oil phase m-cresol into a tower kettle of a rectifying tower, and performing high vacuum rectification to obtain 660g of finished m-cresol with the purity of 99.5%, wherein the yield of the m-cresol is 91.2%.
The test results are shown in Table 1.
Examples 2 to 7
The selective oxidation effect was examined by adjusting the molar ratio of m-cresol to p-cresol according to the reaction conditions in example 1, and the test results are shown in Table 1.
TABLE 1
According to the data of the embodiment 1-7, the selective oxidation catalyst can be used for efficiently converting p-cresol into p-hydroxybenzaldehyde, and simultaneously, the m-cresol is retained, so that the benefit maximization is realized, and the industrial production is easy to realize.
The above-described embodiments are merely preferred embodiments of the present invention, and should not be construed as limiting the scope of the invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention. The invention can oxidize the mixture of m-cresol and p-cresol by using the catalyst for selective oxidation, wherein the p-cresol in the mixture is completely oxidized into p-hydroxybenzaldehyde, and the m-cresol does not react. After the oxidation reaction, because the p-hydroxybenzaldehyde sodium salt is separated by a crystallization mode, the p-hydroxybenzaldehyde sodium salt is dissolved, acidified and filtered to obtain the p-hydroxybenzaldehyde with the purity of more than 99.2 percent; mother liquor is acidified to obtain m-cresol crude product, and high-purity m-cresol with purity of more than 99.5% can be obtained by rectification. The separation method of the invention uses oxygen as oxidant, has mild reaction condition, simple reaction operation and low production cost, and is easy for industrialized production.
Claims (10)
1. A method for preparing high-purity m-cresol by selectively oxidizing m-p-mixed cresol is characterized by comprising the following steps:
1) and (3) oxidation: placing m-cresol and p-cresol mixture, catalyst, sodium hydroxide and solvent into a container, stirring, heating to a reaction temperature, continuously introducing oxygen for reaction, adding water, and distilling to recover the solvent to obtain mother liquor;
2) and (3) crystallization separation: acidifying the mother liquor obtained in the step 1), adjusting the pH value, cooling to crystallize, cooling to 5-10 ℃, and filtering to obtain a filter cake which is p-hydroxybenzaldehyde sodium salt and mother liquor which is m-cresol sodium salt solution;
3) post-treatment of p-hydroxybenzaldehyde sodium salt: dissolving and acidifying the p-hydroxybenzaldehyde sodium salt obtained in the step 2), adjusting pH, cooling for crystallization, cooling to 5-10 ℃, filtering to obtain a filter cake which is a wet p-hydroxybenzaldehyde product, and drying to obtain a p-hydroxybenzaldehyde finished product with the purity of more than 99.2%;
4) after-treatment of the meta-cresol sodium salt solution: acidifying the m-cresol sodium salt solution obtained in the step 2), adjusting the pH value, standing for phase splitting, collecting an oil phase m-cresol crude product and putting the oil phase m-cresol crude product into a tower kettle of a rectifying tower; the height of the rectifying tower is 1.5m, the diameter is 2cm, the tower body is filled with a glass spring, the vacuum silver plating heat preservation is adopted for the tower body, the electric heating jacket is adopted for the tower kettle, the magnetic stirring is adopted, the condenser is cooled by adopting low-temperature water condensation, and the receiving bottle is connected with a high-vacuum mechanical pump; starting magnetic stirring in the tower kettle for stirring, starting a high-vacuum mechanical pump for pressure reduction, starting the tower kettle for heating when the vacuum degree of the system reaches 100-200 Pa, heating, and gradually collecting front distillation, main distillation and back distillation to obtain the m-cresol finished product with the purity of more than 99.5%.
2. The method for preparing high-purity m-cresol using selective oxidation of m-p-cresol mixture according to claim 1, wherein in step 1), the molar ratio of cresol to p-cresol in the m-p-cresol mixture is (50: 1) to (0.01: 1), preferably (2: 1) to (1: 9).
3. The method according to claim 1, wherein in the step 1), the catalyst is a mixture of cobalt acetate, copper acetate and water, and the catalyst component is cobalt acetate: copper acetate: water-4: 1 by mass ratio, and the catalyst is used in an amount of 1-4%, preferably 2-3% by mass of the reactants.
4. The method for preparing high-purity m-cresol using selective oxidation of m-p-mixed cresol according to claim 1, wherein in step 1), the molar ratio of the sodium hydroxide to the m-p-mixed cresol is (3-5): 1, preferably (3.5-4): 1.
5. The method for preparing high-purity m-cresol using selective oxidation of m-p-mixed cresol according to claim 1, wherein in step 1), the solvent is methanol, and the molar ratio of the solvent to the m-p-mixed cresol is (10-15): 1, preferably (12-13): 1.
6. The process for preparing m-cresol with high purity by selective oxidation of m-p-cresol mixture according to claim 1, wherein in step 1), the reaction temperature is 50 to 70 ℃, preferably 60 to 65 ℃.
7. The method for preparing m-cresol with high purity by selectively oxidizing m-p-cresol mixed according to claim 1, wherein the reaction time of the oxygen in step 1) is 4-10 h.
8. The method for preparing m-cresol with high purity by selective oxidation of m-p-cresol mixture according to claim 1, wherein in step 2), the pH value is 10 to 11.
9. The process for preparing m-cresol with high purity by selective oxidation of m-p-cresol mixture according to claim 1, wherein in step 3), the pH value is 6 to 7.
10. The process for preparing m-cresol with high purity by selective oxidation of m-p-cresol mixture according to claim 1, wherein in step 4), the pH value is 6 to 7.
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| US4429163A (en) * | 1978-12-13 | 1984-01-31 | Sumitomo Chemical Company, Limited | Preparation of p-hydroxybenzaldehyde derivatives |
| US4929766A (en) * | 1988-02-24 | 1990-05-29 | Bayer Aktiengesellschaft | Process are the preparation of p-hydroxy-benzaldehydes |
| JPH02172941A (en) * | 1988-12-23 | 1990-07-04 | Sumitomo Chem Co Ltd | Production of p-hydroxybenzaldehyde |
| JPH02172940A (en) * | 1988-12-23 | 1990-07-04 | Sumitomo Chem Co Ltd | Production of p-hydroxybenzaldehyde |
| CN103265415A (en) * | 2013-05-30 | 2013-08-28 | 东营海源化工股份有限公司 | Method for preparing p-hydroxybenzaldehyde and m-hydroxybenzaldehyde from mixed cresol |
| CN109776276A (en) * | 2019-03-20 | 2019-05-21 | 中国科学院青岛生物能源与过程研究所 | A method of M-and P-cresols mixture is separated using selective oxidation catalyst |
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| US4429163A (en) * | 1978-12-13 | 1984-01-31 | Sumitomo Chemical Company, Limited | Preparation of p-hydroxybenzaldehyde derivatives |
| US4929766A (en) * | 1988-02-24 | 1990-05-29 | Bayer Aktiengesellschaft | Process are the preparation of p-hydroxy-benzaldehydes |
| JPH02172941A (en) * | 1988-12-23 | 1990-07-04 | Sumitomo Chem Co Ltd | Production of p-hydroxybenzaldehyde |
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