CN109534982A - A kind of production method of 3,5- di-tert-butyl-4-hydroxybenzoic acid - Google Patents
A kind of production method of 3,5- di-tert-butyl-4-hydroxybenzoic acid Download PDFInfo
- Publication number
- CN109534982A CN109534982A CN201811401862.XA CN201811401862A CN109534982A CN 109534982 A CN109534982 A CN 109534982A CN 201811401862 A CN201811401862 A CN 201811401862A CN 109534982 A CN109534982 A CN 109534982A
- Authority
- CN
- China
- Prior art keywords
- tert
- butyl
- hydroxybenzoic acid
- hexamethylene
- water
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/15—Preparation of carboxylic acids or their salts, halides or anhydrides by reaction of organic compounds with carbon dioxide, e.g. Kolbe-Schmitt synthesis
-
- 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
- C07C37/64—Preparation of O-metal compounds with O-metal group bound to a carbon atom belonging to a six-membered aromatic ring
- C07C37/66—Preparation of O-metal compounds with O-metal group bound to a carbon atom belonging to a six-membered aromatic ring by conversion of hydroxy groups to O-metal groups
Abstract
The invention discloses the production methods of one kind 3,5- di-tert-butyl-4-hydroxybenzoic acid, belong to field of fine chemical, with solve to generate the method for product at present there are conversion ratios it is not high enough, production energy consumption is big the problems such as.Phenates is prepared by sodium hydroxide, hexamethylene reflux water-dividing technique using 2,6 di t butyl phenol；Peter-Michael Kolbe-Schmidt reation is carried out as solvent using pyridine simultaneously, carries out carboxylation.It is mild that the method for the present invention can effectively improve reaction conversion ratio, reaction condition, and solvent can be recycled processing cycle and utilize, and greatly improves the efficiency of industrialized production.
Description
Technical field
The invention belongs to field of fine chemical, and in particular to the producer of one kind 3,5- di-tert-butyl-4-hydroxybenzoic acid
Method.
Background technique
3,5- di-tert-butyl-4-hydroxybenzoic acids are a kind of medicine and chemical intermediate having many uses, and structural formula is as follows:
It can be widely applied to prepare salicylic acid ultraviolet absorbing agent (UV2908, UV120 etc.), while in colour development
Use can also be added in liquid, coating, cosmetics and herbicide.Currently, 3 are prepared both at home and abroad, 5- di-t-butyl -4- hydroxy benzenes first
Sour main method is reacted by Peter-Michael Kolbe-Schmidt (Kolbe-Schmitt), difference be the preparation method of phenolate with
And the reaction condition of carboxylation.The preparation of existing phenolate mainly has toluene/sodium hydroxide point water law, buck high temperature dehydration method, first
Sodium alkoxide/methanol dealcoholysis method, sodium hydride/tetrahydrofuran method etc., wherein sodium hydroxide divides water law and buck high temperature dehydration method to there is temperature
The problem that degree is high, energy consumption is high, conversion ratio is low, and methanol used in sodium methoxide/methanol dealcoholysis method and sodium hydride/tetrahydrofuran method
Sodium and sodium hydride have compared with strict requirements production operation.Phenolate lead to carbon dioxide carry out carboxylation reaction report at present in be all
Using solvent-free, dimethylbenzene or n,N-Dimethylformamide as solvent reaction, condition of no solvent reaction temperature all at 200 DEG C or more,
And ball-milling reaction device is used to be reacted, dimethylbenzene conditioned response conversion ratio is low, and n,N-Dimethylformamide is in phenates
It heats under alkaline condition and easily decomposes, decomposition product can destroy the phenates and transition state of reaction system, and after reaction
Waste water COD is up to 50,000 or more.In conclusion to solve to generate the method for product at present there are conversion ratios not high enough, production energy consumption
The problems such as big.
Summary of the invention
The object of the present invention is to provide the production methods of one kind 3,5- di-tert-butyl-4-hydroxybenzoic acid, current to solve
Generate the method for product there are conversion ratios the problems such as not high enough, production energy consumption is big.
Technical solution of the present invention is as follows: the production method of one kind 3,5- di-tert-butyl-4-hydroxybenzoic acid, using 2,6- bis-
Tert-butyl phenol prepares phenates by sodium hydroxide, hexamethylene reflux water-dividing technique；Simultaneously using pyridine as solvent carry out section
Er Bei-Schmidt reation carries out carboxylation.
As a further improvement of the present invention, after pyridine being added, the hexamethylene of removal system remnants is distilled, then in 115-
Between 120 DEG C, it is passed through dry carbon dioxide, 0.2-0.4Mpa is kept to react 8-10 hours, cool down pressure release, and concentration and recovery is a large amount of
Water is added in pyridine, residue, and toluene is added and is stirred removal of impurities, and water phase adds hydrochloric acid to be acidified, and obtains 3,5- after centrifugal filtration washing
Di-tert-butyl-4-hydroxybenzoic acid.
As a further improvement of the present invention, the mass ratio of 2, the 6- DI-tert-butylphenol compounds, sodium hydroxide, hexamethylene
Are as follows: 1:(0.195-0.215): (3.6-4.5), reaction temperature are system reflux.
As a further improvement of the present invention, the additional amount of the pyridine is the 0.45- of 2,6- DI-tert-butylphenol compounds quality
0.6 times.
As a further improvement of the present invention, increase the drying tower for filling molecular sieve in phenates preparation, separated to drying
Hexamethylene.
The present invention has the advantages that
1, phenates is prepared using sodium hydroxide, hexamethylene reflux water-dividing technique, reaction condition is mild；
2, the drying tower that molecular sieve is filled by increasing can effectively improve reaction 20% or more the rate of preparation of phenates.
3, Peter-Michael Kolbe-Schmidt (Kolbe-Schmitt) reaction is carried out as solvent using pyridine, the conversion of phenates can be made
Rate is increased to 95% or more.
4, the hexamethylene and pyridine that entire technique uses can efficiently separate recovery processing and recycle, and reduce and be produced into
This, reduces three waste discharge.
Specific embodiment
Below with reference to embodiment, the more specific description contents of the present invention.
In the present invention, if not refering in particular to, all parts, percentage are unit of weight, and all equipment and raw material etc. are equal
It is commercially available or the industry is common.Method in subordinate's embodiment is unless otherwise instructed the routine of this field
Method.
Increase the drying tower for filling molecular sieve in following embodiment phenates preparations, to the dry hexamethylene separated.To mention
Height reaction divides water efficiency.
Embodiment 1
In 3000 liters of reaction kettles, 300kg 2,6- DI-tert-butylphenol compounds, 1080kg hexamethylene, 58.5kg sodium hydroxide, steaming is added
Vapour is heated to reflux a point water and switches hexamethylene kettle channel when water distribution component product reaches 10 liters, begin through the hexamethylene separated and fill
Reaction kettle is returned to after the drier of molecular sieve, water distribution component product reaches 26 liters and arrives reaction end (water-separating time 12-14 hours) substantially,
The content of HPLC detection 2,6- DI-tert-butylphenol compounds is lower than 2% after sampling addition benzyl chloride derivatization, and the pyridine of 135kg is added, rises
After a large amount of n-hexane of system is distilled off in temperature, it is continuously heating to 115 DEG C and is passed through dry carbon dioxide, keep 0.2MPa, instead
It answers 8 hours, the pyridine in system is recovered under reduced pressure in cooling pressure release to normal pressure, and 450kg water, 210 kilograms of toluene are then added in kettle
Stirring removal of impurities (needs 2-3 times, water phase samples HPLC detection control 2,6- DI-tert-butylphenol compounds and 2,6- di-t-butyl benzoquinone level
It is transferred to acidification kettle lower than water phase 0.2%), is separated, dilute hydrochloric acid tune PH=1-2 product is added and is precipitated, centrifugal filtration is dry available
Off-white color 3,5- di-tert-butyl-4-hydroxybenzoic acid 310kg, HPLC content >=99%, yield 85.1%.
Embodiment 2
In 3000 liters of reaction kettles, 300kg 2,6- DI-tert-butylphenol compounds, 1080kg hexamethylene, 61kg sodium hydroxide, steam is added
It is heated to reflux a point water, when water distribution component product reaches 10 liters, switches hexamethylene kettle channel, begin through the hexamethylene separated and fill point
Reaction kettle is returned to after the drier of son sieve, water distribution component product reaches 26 liters substantially to reaction end (water-separating time 12-14 hours), takes
The content of HPLC detection 2,6- DI-tert-butylphenol compounds is lower than 2% after sample addition benzyl chloride derivatization, and the pyridine of 150kg is added, heats up
It after a large amount of n-hexane of system is distilled off, is continuously heating to 115 DEG C and is passed through dry carbon dioxide, keep 0.2MPa, reaction 9
Hour, the pyridine in system is recovered under reduced pressure in cooling pressure release to normal pressure, and 450kg water is then added in kettle, and 210 kilograms of toluene stir
Removal of impurities is mixed (to need 2-3 times, water phase samples HPLC detection control 2,6- DI-tert-butylphenol compounds and 2, and 6- di-t-butyl benzoquinone level is low
It in 0.2%), separates water phase and is transferred to acidification kettle, dilute hydrochloric acid tune PH=1-2 product is added and is precipitated, class can be obtained in centrifugal filtration drying
White 3,5- di-tert-butyl-4-hydroxybenzoic acid 288kg, HPLC content >=99%, yield 79.1%.
Embodiment 3
In 3000 liters of reaction kettles, 300kg 2,6- DI-tert-butylphenol compounds, 1080kg hexamethylene, 61kg sodium hydroxide, steam is added
It is heated to reflux a point water, when water distribution component product reaches 10 liters, switches hexamethylene kettle channel, begin through the hexamethylene separated and fill point
Reaction kettle is returned to after the drier of son sieve, water distribution component product reaches 26 liters substantially to reaction end (water-separating time 9-10 hours), takes
The content of HPLC detection 2,6- DI-tert-butylphenol compounds is lower than 2% after sample addition benzyl chloride derivatization, and the pyridine of 180kg is added, heats up
It after a large amount of n-hexane of system is distilled off, is continuously heating to 118 DEG C and is passed through dry carbon dioxide, keep 0.2MPa, reaction 9
Hour, the pyridine in system is recovered under reduced pressure in cooling pressure release to normal pressure, and 450kg water is then added in kettle, and 210 kilograms of toluene stir
Removal of impurities is mixed (to need 2-3 times, water phase samples HPLC detection control 2,6- DI-tert-butylphenol compounds and 2, and 6- di-t-butyl benzoquinone level is low
It in 0.2%), separates water phase and is transferred to acidification kettle, dilute hydrochloric acid tune PH=1-2 product is added and is precipitated, class can be obtained in centrifugal filtration drying
White 3,5- di-tert-butyl-4-hydroxybenzoic acid 315kg, HPLC content >=99%, yield 86.5%.
Embodiment 4
In 3000 liters of reaction kettles, 300kg 2,6- DI-tert-butylphenol compounds, 1100kg hexamethylene, 64.5kg sodium hydroxide, steaming is added
Vapour is heated to reflux a point water and switches hexamethylene kettle channel when water distribution component product reaches 10 liters, begin through the hexamethylene separated and fill
Reaction kettle is returned to after the drier of molecular sieve, water distribution component product reaches 26 liters and arrives reaction end (water-separating time 9-10 hours) substantially,
The content of HPLC detection 2,6- DI-tert-butylphenol compounds is lower than 2% after sampling addition benzyl chloride derivatization, and the pyridine of 170kg is added, rises
After a large amount of n-hexane of system is distilled off in temperature, it is continuously heating to 116 DEG C and is passed through dry carbon dioxide, keep 0.3MPa, instead
It answers and arrives within 10 hours terminal, the pyridine in system is recovered under reduced pressure in cooling pressure release to normal pressure, then the addition 450kg water in kettle, and 210
Kilogram toluene stirring removal of impurities (needs 2-3 time, water phase samples HPLC detection and controls 2,6- DI-tert-butylphenol compounds and 2,6- di-t-butyl
Benzoquinone level is transferred to acidification kettle lower than water phase 0.2%), is separated, and dilute hydrochloric acid tune PH=1-2 product is added and is precipitated, centrifugal filtration is dry
It is dry that off-white color 3,5- di-tert-butyl-4-hydroxybenzoic acid 323kg, HPLC content >=99%, yield 88.7% can be obtained.
Embodiment 5
In 3000 liters of reaction kettles, 300kg 2,6- DI-tert-butylphenol compounds, 1350kg hexamethylene, 62kg sodium hydroxide, steam is added
It is heated to reflux a point water, when water distribution component product reaches 10 liters, switches hexamethylene kettle channel, begin through the hexamethylene separated and fill point
Reaction kettle is returned to after the drier of son sieve, water distribution component product reaches 26 liters substantially to reaction end (water-separating time 7.5-9 hours), takes
The content of HPLC detection 2,6- DI-tert-butylphenol compounds is lower than 2% after sample addition benzyl chloride derivatization, and the pyridine of 180kg is added, heats up
It after a large amount of n-hexane of system is distilled off, is continuously heating to 120 DEG C and is passed through dry carbon dioxide, keep 0.4MPa, reaction 9
Hour, the pyridine in system is recovered under reduced pressure in cooling pressure release to normal pressure, and 450kg water is then added in kettle, and 210 kilograms of toluene stir
Removal of impurities is mixed (to need 2-3 times, water phase samples HPLC detection control 2,6- DI-tert-butylphenol compounds and 2, and 6- di-t-butyl benzoquinone level is low
It in 0.2%), separates water phase and is transferred to acidification kettle, dilute hydrochloric acid tune PH=1-2 product is added and is precipitated, class can be obtained in centrifugal filtration drying
White 3,5- di-tert-butyl-4-hydroxybenzoic acid 330kg, HPLC content >=99%, yield 90.6%.
Embodiment 6
In 3000 liters of reaction kettles, 300kg 2,6- DI-tert-butylphenol compounds, 1200kg hexamethylene, 62kg sodium hydroxide, steam is added
It is heated to reflux a point water, when water distribution component product reaches 10 liters, switches hexamethylene kettle channel, begin through the hexamethylene separated and fill point
Reaction kettle is returned to after the drier of son sieve, water distribution component product reaches 26 liters substantially to reaction end (water-separating time 7.5-9 hours), adds
Enter the content of HPLC detection 2,6- DI-tert-butylphenol compounds after benzyl chloride derivatization lower than 2%, the pyridine of 165kg, heating distillation is added
It after a large amount of n-hexane of removing system, is continuously heating to 115 DEG C and is passed through dry carbon dioxide, keep 0.4MPa, reaction 10 is small
When to terminal, the pressure release that cools down is recovered under reduced pressure the pyridine in system, 450kg water, 210 kilograms of first is then added in kettle to normal pressure
Benzene stirring removal of impurities (needs 2-3 times, water phase samples HPLC detection control 2,6- DI-tert-butylphenol compounds and 2, and 6- di-t-butyl benzoquinones contains
Amount is transferred to acidification kettle lower than water phase 0.2%), is separated, and dilute hydrochloric acid tune PH=1-2 product is added and is precipitated, centrifugal filtration drying can obtain
To 3,5- di-tert-butyl-4-hydroxybenzoic acid 324kg, HPLC content >=99%, yield 89%.
Embodiment 7
In 3000 liters of reaction kettles, 300kg 2,6- DI-tert-butylphenol compounds, 1350kg hexamethylene, 62kg sodium hydroxide, steam is added
It is heated to reflux a point water, when water distribution component product reaches 10 liters, switches hexamethylene kettle channel, begin through the hexamethylene separated and fill point
Reaction kettle is returned to after the drier of son sieve, water distribution component product reaches 26 liters substantially to reaction end (water-separating time 7-9 hours), sampling
The content of HPLC detection 2,6- DI-tert-butylphenol compounds is lower than 2% after addition benzyl chloride derivatization, and the pyridine of 175kg is added, and heating is steamed
It after a large amount of n-hexane of system is removed in distillation, is continuously heating to 118 DEG C and is passed through dry carbon dioxide, keep 0.3MPa, reaction 9 is small
When, the pyridine in system is recovered under reduced pressure in cooling pressure release to normal pressure, and 450kg water, 210 kilograms of toluene stirrings are then added in kettle
Removal of impurities (needs 2-3 times, water phase samples HPLC detection control 2,6- DI-tert-butylphenol compounds and 2, and 6- di-t-butyl benzoquinone level is lower than
0.2%) it, separates water phase and dilute hydrochloric acid acidification PH=1-2 product precipitation, dry available 3, the 5- di-t-butyl -4- of centrifugal filtration is added
Hydroxybenzoic acid 328kg, HPLC content >=99%, yield 90.1%.
Claims (5)
1. one kind 3, the production method of 5- di-tert-butyl-4-hydroxybenzoic acid, it is characterised in that: use 2,6- DI-tert-butylphenol compounds
Phenates is prepared by sodium hydroxide, hexamethylene reflux water-dividing technique；Peter-Michael Kolbe-Schmidt is carried out as solvent using pyridine simultaneously
Reaction carries out carboxylation.
2. a kind of production method of 3,5- di-tert-butyl-4-hydroxybenzoic acid according to claim 1, it is characterised in that:
After pyridine is added, the hexamethylene of distillation removal system remnants is passed through dry carbon dioxide then between 115-120 DEG C, protects
It holds 0.2-0.4Mpa to react 8-10 hours, cool down pressure release, a large amount of pyridines of concentration and recovery, and water is added in residue, and toluene is added and carries out
Stirring removal of impurities, water phase add hydrochloric acid to be acidified, and obtain 3,5- di-tert-butyl-4-hydroxybenzoic acid after centrifugal filtration washing.
3. a kind of production method of 3,5- di-tert-butyl-4-hydroxybenzoic acid according to claim 1 or 2, feature exist
In: 2,6- DI-tert-butylphenol compounds, sodium hydroxide, hexamethylene mass ratio are as follows: 1:(0.195-0.215): (3.6-4.5),
Reaction temperature is system reflux.
4. a kind of production method of 3,5- di-tert-butyl-4-hydroxybenzoic acid according to claim 3, it is characterised in that:
The additional amount of the pyridine is 0.45-0.6 times of 2,6 di t butyl phenol quality.
5. a kind of production method of 3,5- di-tert-butyl-4-hydroxybenzoic acid according to claim 4, it is characterised in that:
Increase the drying tower for filling molecular sieve in phenates preparation, to the dry hexamethylene separated.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811401862.XA CN109534982A (en) | 2018-11-22 | 2018-11-22 | A kind of production method of 3,5- di-tert-butyl-4-hydroxybenzoic acid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811401862.XA CN109534982A (en) | 2018-11-22 | 2018-11-22 | A kind of production method of 3,5- di-tert-butyl-4-hydroxybenzoic acid |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN109534982A true CN109534982A (en) | 2019-03-29 |
Family
ID=65850150
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201811401862.XA Pending CN109534982A (en) | 2018-11-22 | 2018-11-22 | A kind of production method of 3,5- di-tert-butyl-4-hydroxybenzoic acid |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109534982A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116082139A (en) * | 2022-12-27 | 2023-05-09 | 甘肃省化工研究院有限责任公司 | Method and device for preparing salicylic acid ultraviolet absorber |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0834494A1 (en) * | 1996-10-02 | 1998-04-08 | Mitsui Toatsu Chemicals, Incorporated | Process for preparing hydroxybenzoic acids |
| CN1684935A (en) * | 2002-10-01 | 2005-10-19 | 株式会社上野制药应用研究所 | Process for production of hydroxybenzoic acids |
| CN1704395A (en) * | 2004-05-28 | 2005-12-07 | 株式会社上野制药应用研究所 | Method for producing 3,5-di-tert-butyl-4-hydroxybenzoic acid |
| CN104086411A (en) * | 2014-07-18 | 2014-10-08 | 甘肃省化工研究院 | Method for synthesizing 3,5-di-tert-butyl-2-hydroxybenzoic acid |
-
2018
- 2018-11-22 CN CN201811401862.XA patent/CN109534982A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0834494A1 (en) * | 1996-10-02 | 1998-04-08 | Mitsui Toatsu Chemicals, Incorporated | Process for preparing hydroxybenzoic acids |
| CN1684935A (en) * | 2002-10-01 | 2005-10-19 | 株式会社上野制药应用研究所 | Process for production of hydroxybenzoic acids |
| CN1704395A (en) * | 2004-05-28 | 2005-12-07 | 株式会社上野制药应用研究所 | Method for producing 3,5-di-tert-butyl-4-hydroxybenzoic acid |
| CN104086411A (en) * | 2014-07-18 | 2014-10-08 | 甘肃省化工研究院 | Method for synthesizing 3,5-di-tert-butyl-2-hydroxybenzoic acid |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116082139A (en) * | 2022-12-27 | 2023-05-09 | 甘肃省化工研究院有限责任公司 | Method and device for preparing salicylic acid ultraviolet absorber |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN100543012C (en) | Preparation 1,4-diamino-2, the method for 3-dicyan anthraquinone | |
| KR100433023B1 (en) | Manufacturing Method of Diaryl Carbonate | |
| CN108715574B (en) | Method for synthesizing biphenol | |
| US4239913A (en) | Process for preparing 2-hydroxynaphthalenecarboxylic acids | |
| CN103159610B (en) | Method for synthesizing phenoxy carboxylate herbicide original medicine | |
| CN106831315A (en) | A kind of continuous production method of chloroethanes | |
| CN109534982A (en) | A kind of production method of 3,5- di-tert-butyl-4-hydroxybenzoic acid | |
| CN114213217A (en) | Production method and application of p-phenylphenol | |
| US4345095A (en) | Process for the production of 6-hydroxy-2-naphthoic acid | |
| CN109776315A (en) | A method of environment-friendly plasticizer dibenzoic diglycol laurate is prepared by Action In The Liquid Phase Oxidation of Xylene residue | |
| KR950004033B1 (en) | Manufacturing method for 2-hydroxy-naphthalene-6-carboxylic acid | |
| KR870000202B1 (en) | A process for preparing 2-hydroxynaphthalene-6-carboxylic acid selectively | |
| CN107473927B (en) | Preparation process of biphenyl dichlorobenzyl | |
| CN106278983A (en) | A kind of N-Methyl pyrrolidone continuous preparation method | |
| CN109180537B (en) | Method for preparing 3-chloro-p-toluidine-6-sulfonic acid by liquid phase baking method | |
| KR860001855B1 (en) | A process for preparing 2-hydroxynaphthalene-3-carboxylic acid | |
| CN102336690B (en) | Method for separating and purifying high-purity 4,4'-dihydroxydiphenylsulfone | |
| CN100473631C (en) | Process for purifying biphenyl | |
| CN113943218B (en) | Preparation method and application of p-phenyl acetophenone | |
| CN109796331A (en) | A method of 3,5- di-tert-butyl-4-hydroxybenzoic acid is prepared with single solvent | |
| CN109485564B (en) | Novel method for preparing bifenthrin | |
| CN110467538B (en) | Synthesis method of 2-methyl-4-methoxydiphenylamine | |
| JPS61115053A (en) | Production of aromatic hydroxycarboxylic acid | |
| CN1326822C (en) | Process for dehydrating hydrous sodium beta-naphtholate | |
| CN217628182U (en) | Methylamine device and carbon dioxide method DMF wastewater treatment system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20190329 |