CN105017029A - Preparation method of p-bromoaniline - Google Patents
Preparation method of p-bromoaniline Download PDFInfo
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- CN105017029A CN105017029A CN201510420134.3A CN201510420134A CN105017029A CN 105017029 A CN105017029 A CN 105017029A CN 201510420134 A CN201510420134 A CN 201510420134A CN 105017029 A CN105017029 A CN 105017029A
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Abstract
The invention discloses a preparation method of p-bromoaniline, and relates to the organic synthesis technical field; the preparation method comprises the steps: taking aniline as a raw material, firstly under the action of a zinc powder, carrying out an acetylation reaction with acetic acid to generate acetanilide, then undergoing a reaction with bromine to generate p-bromoacetanilide, and finally carrying out hydrolysis and neutralization reaction to obtain p-bromoaniline. The starting material aniline is relatively cheap, the production cost is reduced, moreover, acetic acid, ethanol and mother liquor for production can be used circularly indiscriminately, the COD value of wastewater is reduced greatly, and high economic benefits and social benefits are provided.
Description
Technical field:
The present invention relates to technical field of organic synthesis, be specifically related to a kind of preparation method of para-bromoaniline.
Background technology:
Para-bromoaniline is proterties grey-brown powder shape crystal, there is special odor, for a kind of purposes chemical intermediate widely, be widely used in the synthesis of medicine, dyestuff and other fine chemical products, para-bromoaniline can prepare amine benzenephosphonic acid class medicine in medical, for suppressing the formation of thrombus and preparing chloroquinoline thiazolidinedione as microbiotic etc., convenient at dyestuff, be used for making multiple azoic dyestuff and many rings macromole dyestuff, in addition, also for the preparation of stopper, various sensitive materials, ion exchange resin.The mode that the method for current industrial production para-bromoaniline is still more traditional, there is the problems such as yield is low, purity not high pollution is serious, and production technique is comparatively complicated, is difficult to meet human wants in this traditional production method.
Through retrieval, the synthesis of patent CN 104086444 A para-bromoaniline, and " Institutes Of Technology Of Tianjin's journal " the 26th synthesis of volume the 6th phase o-bromoaniline, take all N-methyl-p-nitroaniline as raw material, be prepared from through steps such as diazotization, bromination, iron powder reducing, steam distillations.But all there is following shortcoming in described method: (1) aniline diazotization is dangerous technique, and misoperation easily security incident occurs; (2) iron powder reducing product separation difficulty, reaction is incomplete, poor product quality; (3) this step of preparation process is long, and production efficiency is low, and cost is high; (4) technique waste discharge many, easily cause environmental pollution, do not meet national cleaner production requirement.
Summary of the invention:
Technical problem to be solved by this invention is to provide the preparation method of the para-bromoaniline that a kind of technique is simple, yield is high.
Technical problem to be solved by this invention adopts following technical scheme to realize:
A preparation method for para-bromoaniline take aniline as raw material, first under zinc powder effect, generates Acetanilide with acetic acid generation acetylization reaction, then generates asepsin with bromine reaction, obtains para-bromoaniline finally by hydrolysis, neutralization reaction.
A preparation method for para-bromoaniline, comprises the following steps:
(1) acetylize: aniline, acetic acid are added in reactor successively, then adds zinc powder, stir, mixture is heated to 50 DEG C of reaction 2-3h, and then vacuum concentration removing acetic acid, adds water in residuum, leave standstill crystallization, filter, dry to obtain Acetanilide;
(2) bromination: above-mentioned obtained Acetanilide is dissolved in acetic acid, the mixture of bromine and acetic acid is dripped after being cooled to less than 10 DEG C, dropwise rear insulation reaction 1-2h, reaction terminates final vacuum concentrated removing acetic acid, in residuum, drip water, and add appropriate sodium bisulfite to remove unreacted bromine, filter, gained solid aqueous acetic acid recrystallization, obtains asepsin;
(3) be hydrolyzed, neutralize: above-mentioned obtained asepsin and ethanol are added in reactor, be heated to boiling, then concentrated hydrochloric acid is added, back flow reaction 1-2h, reaction terminates to add water in backward reaction solution, will pour in cold water in residuum after concentrating out partial solvent, add more than alkali lye adjust ph to 7 again, decrease temperature crystalline, filters washing, namely obtains para-bromoaniline finally by after oven dry.
In described step (1), the mol ratio of aniline and acetic acid is 1:2-10, preferred 1:6.
In described step (2), the mol ratio of Acetanilide and bromine is 1:0.7-1.5, preferred 1:1.03.
In described step (3), asepsin and ethanol weight ratio are 1:2-5, preferred 1:2.
Principle of work of the present invention:
Acetic acid is not only as reaction solvent but also as reaction raw materials in step (1), zinc powder add the acetylize that can promote aniline; Reaction solution is poured in frozen water by aftertreatment, is conducive to Acetanilide crystallization, and can remove out partial impurities and pigment; And the recovery of acetic acid in mother liquor, be conducive to reducing waste liquid, reducing costs.
Acetanilide intermediate is dissolved in cold acetic acid by step (2), and then under agitation drip the miscellany of bromine and acetic acid, object prevents the volatilization of raw material bromine and the generation of side reaction; During aftertreatment, the feed postition of water is for dripping, and crystalline particle can be made larger, improve and separate out yield.
Hydrolyzed solution is steamed part ethanol by step (3), residuum adds water, and is neutralized to pH value for more than 7 with sig water, and object is convenient to product separate out, and lingering section alcohol solvent is conducive to removing out a part of impurity, improves the quality of products.
The invention has the beneficial effects as follows: starting raw material aniline of the present invention is more cheap, reduces production cost, and production acetic acid, ethanol and mother liquor can recycleds, the COD value in waste water greatly reduces, and has higher economic benefit and social benefit.
Embodiment:
The technique means realized to make the present invention, creation characteristic, reaching object and effect is easy to understand, below in conjunction with specific embodiment, setting forth the present invention further.
Embodiment 1
(1) acetylize: in 250mL there-necked flask, adds aniline 20g, acetic acid 52g successively, adds 1g zinc powder simultaneously; stir; 50 DEG C of reacting by heating 3h, then vacuum concentration goes out acetic acid, obtains thick liquid; saturated aqueous solution 30g after adding water or above criticizing Acetanilide crystallization; after stirring, cooling leaves standstill crystallization to completely, filters, obtains Acetanilide solid; 60 DEG C of air blast dry to obtain Acetanilide 28g (94.5%) mp 113-115 DEG C, purity GC >=99.8%.Filtrate cover is used in next batch Acetanilide concentrated solution, for crystallization.
(2) bromination: in 500mL there-necked flask, is dissolved in 50mL acetic acid by Acetanilide 25g and adds successively, and be chilled to less than 10 DEG C, then under agitation drips the mixed platform thing of 36g bromine and 50mL acetic acid, after about 30min adds.At 10 DEG C, continue reaction 1h, then vacuum concentration goes out acetic acid, then adds 250mL water, stirs, then adds 1-2g sodium bisulfite to remove unreacted bromine.Gained solids filters, and obtains 36.2g (95.0%) asepsin with 50% aqueous acetic acid recrystallization.Mp 167-169 DEG C, purity GC >=98.7%.
(3) be hydrolyzed, neutralize: in 500mL there-necked flask, the ethanol (95%) of 50g and 25g asepsin are added, then after being under agitation heated to boil, dividing is added in flask by 30mL concentrated hydrochloric acid three times, after backflow 1h. add 250mL water. then steam about l50mL liquid (second alcohol and water), residuum is poured in 100mL cold water, and the NaOH solution with 5% is neutralized to pH value for 7-8, and be cooled to less than 5 DEG C, crystallization, filtration, with water washing.Obtain para-bromoaniline product 18.8g (96.7%).Mp 62-64 DEG C, purity GC >=98.5%.
Embodiment 2
(1) acetylize: in 1000mL there-necked flask, adds aniline 80g, acetic acid 108g successively, adds 4g zinc powder simultaneously; stir; 50 DEG C of reacting by heating 2h, then vacuum concentration goes out acetic acid, obtains thick liquid; add water 120g; after stirring, cooling leaves standstill crystallization to completely, filters, obtains Acetanilide solid; 60 DEG C of air blast dry to obtain Acetanilide 110g (94.1%) mp 113-115 DEG C, purity GC >=98.8%.Filtrate cover is used in next batch Acetanilide concentrated solution, for crystallization.
(2) bromination: in 1000mL there-necked flask, is dissolved in 100mL acetic acid by Acetanilide 50g and adds successively, and be chilled to less than 5 DEG C, then under agitation drips the mixed platform thing of 70g bromine and 100mL acetic acid, after about 30min adds.At 5 DEG C, continue reaction 1h, then vacuum concentration goes out acetic acid, then adds 500mL water, stirs, then adds 3-5g sodium bisulfite to remove unreacted bromine.Gained solids filters, and obtains 73.1g (95.2%) asepsin with 50% aqueous acetic acid recrystallization.Mp 167-169 DEG C, purity GC >=98.7%.
(3) be hydrolyzed, neutralize: in 1000mL there-necked flask, the ethanol (95%) of 1000mL and 50g asepsin are added, then after being under agitation heated to boil, dividing is added in flask by 60mL concentrated hydrochloric acid three times, after backflow 2h. add 500mL water. then steam about 250mL liquid (second alcohol and water), residuum is poured in 100mL cold water. and the NaOH solution with 5% is neutralized to pH value for 7-7.5 and is cooled to less than 5 degree, and crystallization, filtration, with water washing.Obtain para-bromoaniline product 36.5g (96.4%).Mp 62-64 DEG C, purity GC >=98.9%.
Embodiment 3
(1) amine acetylize: in 250L enamel reaction still, adds aniline 20kg, acetic acid 52kg successively, adds 1kg zinc powder simultaneously; stir; 50 DEG C of reacting by heating 3h, then vacuum concentration goes out acetic acid, obtains thick liquid; add water 30kg; after stirring, cooling leaves standstill crystallization to completely, filters, obtains Acetanilide solid; 60 DEG C of air blast dry to obtain Acetanilide 29kg (95.5%) mp 113-115 DEG C, purity GC >=99.8%.Filtrate cover is used in next batch Acetanilide concentrated solution, for crystallization.
(2) bromination: in 500L enamel reaction still, is dissolved in 50L acetic acid by Acetanilide 25kg and adds successively, and be chilled to less than 10 DEG C, then under agitation drips the mixed platform thing of 35kg bromine and 50L acetic acid, after about 45min adds.At 10 DEG C, continue reaction 2h, then vacuum concentration goes out acetic acid, then adds 250L water, stirs, then adds about 2kg sodium bisulfite to remove unreacted bromine.Gained solids filters, and obtains 35.2kg (94.0%) asepsin with 50% aqueous acetic acid recrystallization.Mp 167-168 DEG C, purity GC >=98.7%.
(3) be hydrolyzed, neutralize: in 500L tri-enamel reaction still, the ethanol (95%) of 50L and 25kg asepsin are added, then after being under agitation heated to boil, dividing is added in flask by 30L concentrated hydrochloric acid three times, after backflow 1h. add 250L water. then steam about l50L liquid (second alcohol and water), then add 50L water.Be neutralized to pH value for 7-8 with 5%NaOH solution, then cool to less than 5 DEG C, sedimentation and filtration. with water washing.Obtain para-bromoaniline product 18.6kg (96.4%).Mp 62-63 DEG C, purity GC >=98.7%.
Embodiment 4
(1) amine acetylize: in 1000L enamel reaction still, adds aniline 80kg, acetic acid 208kg successively, adds 4kg zinc powder simultaneously; stir; 50 DEG C of reacting by heating 2h, then vacuum concentration goes out acetic acid, obtains thick liquid; add water 120kg; after stirring, cooling leaves standstill crystallization to completely, filters, obtains Acetanilide solid; 60 DEG C of air blast dry to obtain Acetanilide 120kg (95.8%) mp 113-114 DEG C, purity GC >=99.5%.Filtrate cover is used in next batch Acetanilide concentrated solution, for crystallization.
(2) bromination: in 1000L enamel reaction still, is dissolved in 100L acetic acid by Acetanilide 50kg and adds successively, and be chilled to less than 5 DEG C, then under agitation drips the mixed platform thing of 70kg bromine and 100L acetic acid, after about 60min adds.At 10 DEG C, continue reaction 2h, then vacuum concentration goes out acetic acid, then adds 500L water, stirs, then adds about 4kg sodium bisulfite to remove unreacted bromine.Gained solids filters, and obtains 69.5kg (93.5%) asepsin with 50% aqueous acetic acid recrystallization.Mp 168-169 DEG C, purity GC >=98.6%.
(3) be hydrolyzed, neutralize: in 1000L tri-enamel reaction still, the ethanol (95%) of 100L and 50kg asepsin are added, then after being under agitation heated to boil, dividing is added in flask by 60L concentrated hydrochloric acid three times, after backflow 1h. add 500L water. then steam about 250L liquid (second alcohol and water), then add 100L water.NaOH solution with 5% is neutralized to pH value for 7-8, then lowers the temperature less than 5 DEG C, by sedimentation and filtration. with water washing.Obtain para-bromoaniline product 37.5kg (96.5%).Mp 62-63 DEG C, purity GC >=98.7%.
More than show and describe ultimate principle of the present invention and principal character and advantage of the present invention.The technician of the industry should understand; the present invention is not restricted to the described embodiments; what describe in above-described embodiment and specification sheets just illustrates principle of the present invention; without departing from the spirit and scope of the present invention; the present invention also has various changes and modifications, and these changes and improvements all fall in the claimed scope of the invention.Application claims protection domain is defined by appending claims and equivalent thereof.
Claims (4)
1. a preparation method for para-bromoaniline, is characterized in that: take aniline as raw material, first under zinc powder effect, generates Acetanilide with acetic acid generation acetylization reaction, then generates asepsin with bromine reaction, obtains para-bromoaniline finally by hydrolysis, neutralization reaction.
2. a preparation method for para-bromoaniline, is characterized in that, comprises the following steps:
(1) acetylize: aniline, acetic acid are added in reactor successively, then adds zinc powder, stir, mixture is heated to 50 DEG C of reaction 2-3h, and then vacuum concentration removing acetic acid, adds water in residuum, leave standstill crystallization, filter, dry to obtain Acetanilide;
(2) bromination: above-mentioned obtained Acetanilide is dissolved in acetic acid, the mixture of bromine and acetic acid is dripped after being cooled to less than 10 DEG C, dropwise rear insulation reaction 1-2h, reaction terminates final vacuum concentrated removing acetic acid, in residuum, drip water, and add appropriate sodium bisulfite to remove unreacted bromine, filter, gained solid aqueous acetic acid recrystallization, obtains asepsin;
(3) be hydrolyzed, neutralize: above-mentioned obtained asepsin and ethanol are added in reactor, be heated to boiling, then concentrated hydrochloric acid is added, back flow reaction 1-2h, reaction terminates to add water in backward reaction solution, will pour in cold water in residuum after concentrating out partial solvent, add more than alkali lye adjust ph to 7 again, decrease temperature crystalline, filters washing, namely obtains para-bromoaniline finally by after oven dry.
3. the preparation method of para-bromoaniline according to claim 2, is characterized in that: in described step (1), the mol ratio of aniline and acetic acid is 1:2-10, preferred 1:6.
4. the preparation method of para-bromoaniline according to claim 2, is characterized in that: in described step (2), the mol ratio of Acetanilide and bromine is 1:0.7-1.5, preferred 1:1.03.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107652198A (en) * | 2017-10-09 | 2018-02-02 | 新乡市锦源化工有限公司 | The preparation method of antifebrin |
| CN107935877A (en) * | 2017-12-07 | 2018-04-20 | 新乡市锦源化工有限公司 | A kind of method of new catalytic synthesis antifebrin |
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2015
- 2015-07-15 CN CN201510420134.3A patent/CN105017029A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107652198A (en) * | 2017-10-09 | 2018-02-02 | 新乡市锦源化工有限公司 | The preparation method of antifebrin |
| CN107652198B (en) * | 2017-10-09 | 2020-04-07 | 新乡市锦源化工有限公司 | Process for preparing acetanilide |
| CN107935877A (en) * | 2017-12-07 | 2018-04-20 | 新乡市锦源化工有限公司 | A kind of method of new catalytic synthesis antifebrin |
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Application publication date: 20151104 |