CN108358776A - The preparation method of 4- chloromethyl benzoic acid chlorides - Google Patents
The preparation method of 4- chloromethyl benzoic acid chlorides Download PDFInfo
- Publication number
- CN108358776A CN108358776A CN201810085139.9A CN201810085139A CN108358776A CN 108358776 A CN108358776 A CN 108358776A CN 201810085139 A CN201810085139 A CN 201810085139A CN 108358776 A CN108358776 A CN 108358776A
- Authority
- CN
- China
- Prior art keywords
- benzoic acid
- acid chlorides
- chlorine
- product
- dosage
- 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.)
- Withdrawn
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
- C07C51/58—Preparation of carboxylic acid halides
- C07C51/60—Preparation of carboxylic acid halides by conversion of carboxylic acids or their anhydrides or esters, lactones, salts into halides with the same carboxylic acid part
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/62—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by introduction of halogen; by substitution of halogen atoms by other halogen atoms
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/093—Preparation of carboxylic acids or their salts, halides or anhydrides by hydrolysis of —CX3 groups, X being halogen
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/58—Preparation of carboxylic acid halides
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/58—Preparation of carboxylic acid halides
- C07C51/62—Preparation of carboxylic acid halides by reactions not involving the carboxylic acid halide group
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a kind of preparation method of 4 chloromethyl benzoic acid chlorides, step is:(1)Under the effect of catalyst dibenzoyl peroxide, the step of chlorination occurs, prepares 4 methylol, three benzyl chloride crude product by 4 xylyl alcohols and chlorine;(2)By step(1)The step of hydrolysis occurs for 4 methylol, the three benzyl chloride crude product and water prepared;(3)By step(2)Hydrolysate and excessive oxalyl chloride, under catalyst DMF effect, the step of acylation reaction occurs, prepares 4 chloromethyl benzoic acid chlorides of target product.Technique raw material of the present invention are easy to get, cheap;It is easy to operate;The rare side reaction of whole process occurs;Low energy consumption;Product quality is high;Product cost is low;The three wastes are few, and total yield of products is between 85 ~ 90%, 99% or more purity.
Description
Technical field
The present invention relates to a kind of preparation methods of 4- chloromethyl benzoic acid chlorides, belong to fine chemistry industry organic synthesis technology neck
Domain.
Background technology
4- chloromethyl benzoic acid chlorides, colourless liquid, CAS:876-08-4, molecular formula C8H6Cl2O is a kind of important doctor
Medicine, pesticide, dyestuff and material intermediate, structural formula are as follows:
In recent years, multiple fields are increasingly used in as raw material drug due to 4- chloromethyl benzoic acid chlorides, this
As a result market is promoted to increase the demand of 4- chloromethyl benzoic acid chlorides year by year, to make practitioner see 4- chloromethylbenzene first
Therefore the broad prospect of application of acyl chlorides studies the preparation method of 4- chloromethyl benzoic acid chlorides to have obtained more and more attention.
Currently, in relation to 4- chloromethyl benzoic acid chlorides preparation of industrialization research be rarely reported, but be summed up mainly have with
Lower synthetic route:
(1) 4- chlorotoluenes pendant chlorine generates one benzyl chloride of 4- chlorine, then reacts generation with oxalyl chloride under the action of catalyst
4- chloromethyl benzoic acid chlorides.Synthetic route is as follows:
(2) 4- methyl benzoic acids pendant chlorine generate 4- chloromethyl benzoic acids, then under the action of catalyst with oxalyl chloride
Reaction generates 4- chloromethyl benzoic acid chlorides, and synthetic route is as follows:
(3) 4- hydroxymethyl-benzoic acids react synthesis 4- chloromethylbenzene first with oxalyl chloride or thionyl chloride under the action of catalyst
Acyl chlorides, synthetic route are as follows:
Other than above common several preparation methods, also document report is led to chlorine with 4- methyl benzoyl chlorides and must be produced
Object.
By the reaction mechanism of method (1) it is found that 4- chlorotoluene pendant chlorines are readily generated one benzyl chloride of 4- chlorine, 4- chlorine dichloros
Three benzyl chloride of benzyl and 4- chlorine, the possibility that chlorination in addition to this occurs on phenyl ring is also very big, that is, is easy to generate dichloro or more chlorine pairs
Product.The chlorination reaction mechanism of method (2) and method (1) some similar, corresponding benzyl dichloride, three benzyl chlorides and dichloro and more chlorine
By-product all it is possible that, this results in above-mentioned preparation method there are following drawback, first, yield is low;Second, by-product
It is more, and some by-products are close with principal product boiling point, it is difficult to detach, cause product purity low, it is of low quality;Third detaches energy
Consumption is big;4th, it is of high cost.As for method (3) due to expensive raw material price, and yield is not high, it is difficult to realize industrialization.
Invention content
The object of the present invention is to provide a kind of low in raw material price, reaction is simple, side reaction is few, product yield is high, product
The preparation method of high-quality 4- chloromethyl benzoic acid chlorides.
A kind of preparation method of 4- chloromethyl benzoic acid chlorides of the present invention, includes the following steps:
(1) chlorination.Using 4- xylyl alcohols as raw material, it is as catalyst, with triethanolamine using dibenzoyl peroxide
Chlorine is led in the inhibitor of anti-phenyl ring chlorination, heating, and the hydrogen chloride gas of generation enters liquid caustic soda surge tank or water by vacuum absorption
Slot, dibenzoyl peroxide are added portionwise, and per hour plus primary, triethanolamine is added at one time.GC gas-chromatographies track, with 4-
Amount≤0.05% of methylol benzyl dichloride is terminal, stops leading to chlorine, and reaction terminates, and cools down, gained chlorated liquid 4- methylols three
Benzyl chloride crude product is for use.Chlorination route is as follows:
(2) hydrolysis.Above-mentioned chlorated liquid is raised to certain temperature, water is slowly added dropwise, with the amount of three benzyl chloride of 4- methylols
≤ 0.05%, reaction was completed, and reduces temperature to room temperature.Although the reaction has the by-product 4- hydroxymethyl-benzoic acids less than 5%,
But this is also the raw material for synthesizing target product.Hydrolysis is as follows:
(3) acylation reaction.Ether is added in above-mentioned system and quantitative catalyst DMF opens stirring, was added dropwise at room temperature
The oxalyl chloride of amount, amount >=95% with 4- chloromethyl benzoic acid chlorides are reaction end, and normal pressure recycles ether and oxalyl chloride.5% liquid
Alkali neutralization remainder system makes pH=7~8, stands, layering, point falls water layer, to organic phase depressurized (6mmHg) recycling 126~
128 DEG C of fractions obtain product 4- chloromethyl benzoic acid chlorides.Acylation reaction route is as follows:
In above-mentioned steps (1), the logical chlorine speed control of chlorine is in 100~500ml/min.The dosage of dibenzoyl peroxide
It is 0.001~0.005 times of 4- methylol benzylalcohol quality;The dosage of triethanolamine is 0.4 times of dibenzoyl peroxide quality;
At 60~105 DEG C, the reaction time is subject to the spectrum display of GC gas for holding temperature control.
In above-mentioned steps (2), temperature control is at 50~80 DEG C, and the reaction time is subject to the spectrum display of GC gas, and water is to react
Subject to terminal.
In above-mentioned steps (3), the dosage of ether is 3~6 times, preferably 3~4 times of system quality.The dosage of catalyst DMF
For 0.002~0.01 times of system quality after hydrolysis, preferably 0.002~0.005 times.The mole dosage of oxalyl chloride is 4- methyl benzyls
1.2~2.5 times of alcohol, preferably 2~2.5 times.
The present invention has following remarkable advantage compared with prior art:Raw material are easy to get, cheap;It is easy to operate;It is whole
A rare side reaction of process occurs;Low energy consumption;Product quality is high;Product cost is low;The three wastes are few.Total yield of products is 85~90%
Between, 99% or more purity is suitble to industrialized production, has good application prospect.
Specific implementation mode
Specific embodiment is will be given below, for the present invention is described further.
Embodiment 1
By reaction of the dibenzoyl peroxide of the 4- xylyl alcohols of 300g and the 0.075g input with device for absorbing tail gas
In device, stirring is opened, triethanolamine 5, which is added dropwise, with rubber head dropper drips about 0.12g, and closed reactor starts to warm up, waits rising to 55
DEG C, it opens chlorine valve and leads to chlorine, logical chlorine speed is arranged in 400~500ml/min.The reaction is exothermic reaction, temperature meeting
It is automatic to rise, it waits rising to 60 DEG C or more, starts to keep the temperature, temperature is in 60~75 DEG C always in insulating process.It is every to mend after an hour
Add dibenzoyl peroxide 0.075g, is no longer added after adding three times.The spectrum tracking of GC gas keeps the temperature gas spectrum display after 8h, 4- hydroxyls
Amount≤0.05% of methyl dichloro benzyl is terminal, stops leading to chlorine, and reaction terminates, and drives extra chlorine away with nitrogen, cools down, institute
Three benzyl chloride crude product about 571g of chlorated liquid 4- methylols is obtained, for use.
The temperature of above-mentioned system is risen to 60 DEG C or more, starts that water, rate of addition control is added dropwise with 200ml constant pressure funnels
System is added dropwise after 1h to suspend and is added dropwise in 1 drop/5s, the spectrum tracking of GC gas, after 19h gas spectrum show the amount of three benzyl chloride of 4- methylols≤
0.05%, reaction terminates, and institute's water consumption is 116g, is then cooled to room temperature, weighs to whole system, gross weight 659g, root
According to the conservation of mass it is found that there is the hydrogen chloride gas of 28g to enter device for absorbing tail gas.
The DMF catalyst of the ether of 2636g and 2g are put into above-mentioned system, open stirring, and temperature is controlled in room
Temperature.Starting that oxalyl chloride 624g is added dropwise, rate of addition is controlled in 100g/h, is added dropwise that the reaction was continued, the spectrum tracking of GC gas, after 14h,
The amount of 4- chloromethyl benzoic acid chlorides is 96.3%, and reaction terminates, and normal pressure recycling ether and oxalyl chloride, recycling finish, with 5% liquid caustic soda
Remaining system is neutralized, is terminal with pH=7~8, is stood, layering, after removing water layer, (6mmHg) is depressurized to organic phase and is returned
126~128 DEG C of fractions are received, product 4- chloromethyl benzoic acid chlorides 412g, yield 88.8%, purity 99.4% are obtained.
Embodiment 2
By reaction of the dibenzoyl peroxide of the 4- xylyl alcohols of 300g and the 0.075g input with device for absorbing tail gas
In device, stirring is opened, triethanolamine 5, which is added dropwise, with rubber head dropper drips about 0.12g, and closed reactor starts to warm up, waits rising to 55
DEG C, it opens chlorine valve and leads to chlorine, logical chlorine speed is arranged in 100~150ml/min.The reaction is exothermic reaction, temperature meeting
It is automatic to rise, it waits rising to 60 DEG C or more, starts to keep the temperature, temperature is in 60~75 DEG C always in insulating process.It is every to mend after an hour
Add dibenzoyl peroxide 0.075g, is no longer added after adding three times.The spectrum tracking of GC gas keeps the temperature gas spectrum display after 12h, 4- hydroxyls
Amount≤0.05% of methyl dichloro benzyl is terminal, stops leading to chlorine, and reaction terminates, and drives extra chlorine away with nitrogen, cools down, institute
Three benzyl chloride crude product about 560g of chlorated liquid 4- methylols is obtained, for use.
The temperature of above-mentioned system is risen to 50 DEG C or more, starts that water, rate of addition control is added dropwise with 200ml constant pressure funnels
System is added dropwise after 1h to suspend and is added dropwise in 1 drop/5s, the spectrum tracking of GC gas, after 21h gas spectrum show the amount of three benzyl chloride of 4- methylols≤
0.05%, reaction terminates, and institute's water consumption is 116g, is then cooled to room temperature, weighs to whole system, gross weight 645g, root
According to the conservation of mass it is found that there is the hydrogen chloride gas of 31g to enter device for absorbing tail gas.
The DMF catalyst of the ether of 1935g and 1.3g are put into above-mentioned system, open stirring, and temperature control is existed
Room temperature.Start that oxalyl chloride 654g is added dropwise, rate of addition is controlled in 100g/h, is added dropwise that the reaction was continued, the spectrum tracking of GC gas, 12h
Afterwards, the amount of 4- chloromethyl benzoic acid chlorides is 95.5%, and reaction terminates, and normal pressure recycling ether and oxalyl chloride, recycling finish, with 5%
It is terminal with pH=7~8 with remaining system in liquid caustic soda, stands, layering depressurizes organic phase after removing water layer
(6mmHg) recycles 126~128 DEG C of fractions, obtains product 4- chloromethyl benzoic acid chlorides 418g, yield 90.1%, purity 99.6%.
Embodiment 3
By reaction of the dibenzoyl peroxide of the 4- xylyl alcohols of 300g and the 0.375g input with device for absorbing tail gas
In device, stirring is opened, triethanolamine 25, which is added dropwise, with rubber head dropper drips about 0.6g, and closed reactor starts to warm up, waits rising to 70
DEG C, it opens chlorine valve and leads to chlorine, logical chlorine speed is arranged in 400~500ml/min.The reaction is exothermic reaction, temperature meeting
It is automatic to rise, it waits rising to 70 DEG C or more, starts to keep the temperature, temperature is in 70~85 DEG C always in insulating process.It is every to mend after an hour
Add dibenzoyl peroxide 0.375g, is no longer added after adding three times.The spectrum tracking of GC gas keeps the temperature gas spectrum display after 6.5h, 4-
Amount≤0.05% of methylol benzyl dichloride is terminal, stops leading to chlorine, and reaction terminates, and drives extra chlorine away with nitrogen, cools down,
Three benzyl chloride crude product about 549g of gained chlorated liquid 4- methylols, for use.
The temperature of above-mentioned system is risen to 70 DEG C or more, starts that water, rate of addition control is added dropwise with 200ml constant pressure funnels
System is added dropwise after 1h to suspend and is added dropwise in 1 drop/5s, the spectrum tracking of GC gas, after 19h gas spectrum show the amount of three benzyl chloride of 4- methylols≤
0.05%, reaction terminates, and institute's water consumption is 116g, is then cooled to room temperature, weighs to whole system, gross weight 637g, root
According to the conservation of mass it is found that there is the hydrogen chloride gas of 28g to enter device for absorbing tail gas.
The DMF catalyst of the ether of 1911g and 3.2g are put into above-mentioned system, open stirring, and temperature control is existed
Room temperature.Start that oxalyl chloride 654g is added dropwise, rate of addition is controlled in 100g/h, is added dropwise that the reaction was continued, the spectrum tracking of GC gas, 14h
Afterwards, the amount of 4- chloromethyl benzoic acid chlorides is 96.1%, and reaction terminates, and normal pressure recycling ether and oxalyl chloride, recycling finish, with 5%
It is terminal with pH=7~8 with remaining system in liquid caustic soda, stands, layering depressurizes organic phase after removing water layer
(6mmHg) recycles 126~128 DEG C of fractions, obtains product 4- chloromethyl benzoic acid chlorides 409g, yield 88.1%, purity 99.3%.
Embodiment described above is only described the preferred embodiment of the present invention, not to the present invention's
Range is set, and without departing from the spirit of the invention, those of ordinary skill in the art are to technical scheme of the present invention
The modification and improvement done should all be fallen into the protection domain of claims of the present invention determination.
Claims (9)
1. the method for preparing 4- chloromethyl benzoic acid chlorides, which is characterized in that include the following steps:
(1)Under the effect of catalyst dibenzoyl peroxide, chlorination is occurred into for 4- xylyl alcohols and chlorine, prepares 4- hydroxyl first
The step of three benzyl chloride crude product of base,
;
(2)By step(1)The step of hydrolysis, occurs for the three benzyl chloride crude product of 4- methylols and water of preparation,
(3)Under catalyst DMF effects, by step(2)Hydrolysate and excessive oxalyl chloride occur acylation reaction, prepare mesh
The step of marking product 4- chloromethyl benzoic acid chlorides,
。
2. the method as described in claim 1, which is characterized in that step(1)In, chlorine be passed through speed control 100 ~
500ml/min。
3. the method as described in claim 1, which is characterized in that step(1)In, the dosage of dibenzoyl peroxide is 4- hydroxyl first
0.001 ~ 0.005 times of base benzylalcohol quality.
4. the method as described in claim 1, which is characterized in that step(1)In, it reacts in anti-three ethyl alcohol of phenyl ring chlorination inhibitor
It is carried out in the presence of amine, the dosage of triethanolamine is 0.4 times of dibenzoyl peroxide quality.
5. the method as described in claim 1, which is characterized in that step(1)In, chlorination temperature is controlled at 60 ~ 105 DEG C.
6. the method as described in claim 1, which is characterized in that step(2)In, hydrolysising reacting temperature is controlled at 50 ~ 80 DEG C.
7. the method as described in claim 1, which is characterized in that step(3)In, the solvent of reaction system is ether, ether
Dosage is 3 ~ 6 times of system quality.
8. the method as described in claim 1, which is characterized in that step(3)In, the dosage of catalyst DMF is step(2)Water
Solve 0.002 ~ 0.01 times of product quality.
9. the method as described in claim 1, which is characterized in that step(3)In, the mole dosage of oxalyl chloride is 4- xylyl alcohols
1.2 ~ 2.5 times.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN201810085139.9A CN108358776A (en) | 2018-01-29 | 2018-01-29 | The preparation method of 4- chloromethyl benzoic acid chlorides |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN201810085139.9A CN108358776A (en) | 2018-01-29 | 2018-01-29 | The preparation method of 4- chloromethyl benzoic acid chlorides |
Publications (1)
Publication Number | Publication Date |
---|---|
CN108358776A true CN108358776A (en) | 2018-08-03 |
Family
ID=63007401
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CN201810085139.9A Withdrawn CN108358776A (en) | 2018-01-29 | 2018-01-29 | The preparation method of 4- chloromethyl benzoic acid chlorides |
Country Status (1)
Country | Link |
---|---|
CN (1) | CN108358776A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN109721466A (en) * | 2019-01-22 | 2019-05-07 | 江苏佳麦化工有限公司 | A kind of synthetic method of benzyl chloride |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2004108699A1 (en) * | 2003-06-06 | 2004-12-16 | Natco Pharma Limited | Process for the preparation of the anti-cancer drug imatinib and its analogues |
CN102351704A (en) * | 2011-08-25 | 2012-02-15 | 浙江巍华化工有限公司 | Method for synthesizing methyl 3-(trifluoromethyl)benzoate |
CN102863383A (en) * | 2011-07-08 | 2013-01-09 | 华东理工大学 | Preparation method of oxygen bleaching activator tribasic copper chloride (TBCC) |
-
2018
- 2018-01-29 CN CN201810085139.9A patent/CN108358776A/en not_active Withdrawn
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2004108699A1 (en) * | 2003-06-06 | 2004-12-16 | Natco Pharma Limited | Process for the preparation of the anti-cancer drug imatinib and its analogues |
CN102863383A (en) * | 2011-07-08 | 2013-01-09 | 华东理工大学 | Preparation method of oxygen bleaching activator tribasic copper chloride (TBCC) |
CN102351704A (en) * | 2011-08-25 | 2012-02-15 | 浙江巍华化工有限公司 | Method for synthesizing methyl 3-(trifluoromethyl)benzoate |
Non-Patent Citations (1)
Title |
---|
于康平 等: "对氯苯甲酰氯的合成", 《现代农药》 * |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN109721466A (en) * | 2019-01-22 | 2019-05-07 | 江苏佳麦化工有限公司 | A kind of synthetic method of benzyl chloride |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CN109534975B (en) | Catalytic synthesis method of 2-hydroxybenzophenone compound | |
CN105037139B (en) | A kind of 2 phenylpropionic acid preparation methods | |
CN108358776A (en) | The preparation method of 4- chloromethyl benzoic acid chlorides | |
CN105777584B (en) | The preparation method of alanine derivatives | |
CN103058984B (en) | Synthesis method of watermelon ketone | |
CN107652226B (en) | Preparation method of N-Boc-4-piperidine formaldehyde | |
CN107324964B (en) | Synthetic method of biphenyl derivative | |
CN105330556A (en) | Preparation method of dimethylaminoethyl acrylate and catalyst thereof | |
CN113233958B (en) | Preparation method of 2- (trans-4-n-propylcyclohexyl) propane-1, 3-diol | |
CN112592274B (en) | Process for synthesizing methyl p-hydroxyphenylpropionate | |
CN104030922A (en) | Method for preparing dimethyl n-butyl malonate | |
TW310317B (en) | ||
CN106831362A (en) | The production method of 2 propoxyl group chloroethanes | |
CN105732540A (en) | Method for preparing amic acid and application thereof | |
CN104003929B (en) | A kind of synthetic method of α, α-diphenyl-4-piperidine carbinols | |
CN102206155A (en) | Method for synthesizing ethyl 4,4-difluoroacetoacetate | |
CN107880011B (en) | The synthetic method of Lu Makatuo key intermediate | |
JP2002179611A (en) | Method for producing dicarboxylic acid compound | |
TW202000636A (en) | Process for preparing bis(2-hydroxyethyl) terephthalate | |
CN109180441A (en) | A kind of synthetic method of triethyl orthoformate | |
CN110483319A (en) | A kind of preparation method of N- alkyloxy oxalyl alanine ester | |
CN103342639A (en) | Method for synthesizing 2-phenylcarboxylate | |
CN109851518A (en) | The preparation method of the aceted intermediate of the fluoro- 3- methyl isobenzofuran -3- ketone of one kind (S) -5- | |
CN108395415A (en) | A method of preparing 1- (3- bromopropyls) -1,4- phenodiazine cycloheptane hydrobromates | |
CN106588680A (en) | Lauryl betaine preparation method |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PB01 | Publication | ||
SE01 | Entry into force of request for substantive examination | ||
SE01 | Entry into force of request for substantive examination | ||
WW01 | Invention patent application withdrawn after publication | ||
WW01 | Invention patent application withdrawn after publication |
Application publication date: 20180803 |