CN104326928A - Method for preparing 4-aminobenzoic acid by catalytic hydrogenation - Google Patents
Method for preparing 4-aminobenzoic acid by catalytic hydrogenation Download PDFInfo
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- CN104326928A CN104326928A CN201410656591.8A CN201410656591A CN104326928A CN 104326928 A CN104326928 A CN 104326928A CN 201410656591 A CN201410656591 A CN 201410656591A CN 104326928 A CN104326928 A CN 104326928A
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Abstract
The invention relates to the field of production of 4-aminobenzoic acid and specifically relates to a method for preparing 4-aminobenzoic acid by catalytic hydrogenation. The method comprises the following steps: preparing a water solution of a neutral sodium salt from 4-nitrobenzoic acid and the equal molar amount of an alkali (sodium hydroxide) for preparing 4-nitrobenzoate by using 3 times the mass of solvent water the mass of which is 3 times that of 4-nitrobenzoic acid and alkali, performing hydrogenation reduction for 2h by taking 5% Pd/C as a catalyst, controlling the pressure of hydrogen to 1-2MPa and controlling the temperature to 60-70 degrees till the pressure is not reduced basically to obtain the water solution of the sodium salt, further acidifying and filtering to obtain white 4-aminobenzoic acid, wherein the yield is above 95% and the purity is above 99%. The method provided by the invention has the advantages of perfect process, low energy consumption, short reaction period and no corrosion and is safe to operate, and the environment-friendly process for preparing 4-aminobenzoic acid by taking 4-nitrobenzoic acid as a raw material and performing catalytic hydrogenation at low temperature and low pressure is high in production efficiency.
Description
Technical field
The present invention relates to PABA production field, be specifically related to a kind of method that shortening prepares PABA.
Background technology
Para-amino benzoic acid is one of body cell growth and the integral part dividing necessary material folic acid, and in yeast, liver, wheat bran, Fructus Hordei Germinatus, content is very high.
Be mainly used in dyestuff and medicine intermediate.For the production of reactive red M-80, M-10B, dyestuffs such as reactive red violet X-2R and produce cyanobenzoic acid and produce medicine para-amino-methyl-benzoic acid.Para-amino benzoic acid can be used as sun-screening agent, and its derivative, to dimethylamino octyl formate, is excellent sun-screening agent.
The synthetic method of this compound has following several at present:
One: take p-nitrobenzoic acid as raw material iron powder reducing gained
This technique is the main route of current suitability for industrialized production, but at present iron powder reducing technique to there is wastewater flow rate very large, a lot of and very unmanageable problem of solid waste iron mud; Need to use a large amount of hydrochloric acid, to the serious corrosion of equipment simultaneously; The reaction time of reduction is long, often criticizes the shortcoming about needing 10h.
Two: take p-nitrobenzoic acid as raw material, Raney's nickel Hydrogenation is for gained
This technique is also one of main route of suitability for industrialized production at present, but the reduction temperature that this reduction requires is higher, and need to reach about 140 degree, also higher needs reaches 4MPa to the hydrogen pressure reduced simultaneously, time needed for reduction is relatively also long, about needs 6h.The safety coefficient that therefore can there is this hydrogenation requires high, the shortcoming that observable index is higher.
Three: be that raw material first reduces at oxidation gained with para-nitrotoluene
This operational path is long, and the meaning of suitability for industrialized production is not very large.
Summary of the invention
In order to solve the problem, the present invention proposes a kind of method that shortening prepares PABA, with 4-nitrobenzoic acid for shortening under raw material low temperature, low pressure prepares the environmental protection technique of PABA, energy consumption is low, low to equipment corrosion, reaction times is short, greatly enhances productivity.
In order to reach foregoing invention object, the present invention proposes following technical scheme:
A kind of shortening prepares the method for PABA, 4-nitrobenzoic acid and equimolar amount prepare the alkali (sodium hydroxide) of 4-nitrobenzoate, the aqueous solvent of 3 times of quality is mixed with the aqueous solution of its neutral sodium-salt, and 5% Pd/C is catalyzer, controls hydrogen pressure at 1-2MPa, temperature is at 60-70 degree, hydrogenating reduction 2h extremely not step-down substantially, its sodium-salt aqueous solution of gained, then acidifying filtration obtains white PABA, yield more than 95%, purity more than 99%.
Between the quality of described aqueous solvent is 2 times-10 times of 4-nitrobenzoic acid quality, present method requires that 3 times for good.
The alkali of described preparation 4-nitrobenzoate can be the one in sodium hydroxide, potassium hydroxide, lithium hydroxide.
Described catalyzer can be the one in 5%Pd/C, 10%Pd/C, 7 ‰ Pd/Al2O3,5%Pt/C, 5%Ru/C, and present method requires that 5%Pd/C is good.
The pressure of described hydrogen can between 0.5-6MPa, and present method requires that 1-2MPa is good.
The temperature of described reduction can between 40-100 degree, and present method requires that 60-70 degree is good.
Advantage of the present invention is perfect technology, operational safety, and energy consumption is low, and reaction time is short, corrosion-free, and with 4-nitrobenzoic acid for shortening under raw material low temperature, low pressure prepares the environmental protection technique of PABA, production efficiency is high.
Embodiment
Example one:
50g 4-nitrobenzoic acid and 12g sodium hydroxide, 150g water are mixed with the aqueous solution of 4-nitrobenzoyl acid sodium-salt, join in 1L autoclave, and add 0.5g 5%Pd/C, after nitrogen replacement three times, hydrogen exchange secondary, supplementary pressure is to 2MPa, control temperature is at 60-70 degree, react and substantially do not fall to pressure, after about 2h, reclaim catalyzer.Gained reaction solution concentrated hydrochloric acid is acidified to pH value 3, filters washing and obtains white solid PABA, obtain product 38.9g, yield 95%, purity 99.5%(HPLC after drying).
Example two:
100g 4-nitrobenzoic acid and 24g sodium hydroxide, 300g water are mixed with the aqueous solution of 4-nitrobenzoyl acid sodium-salt, join in 1L autoclave, and add 1.0g 5%Pd/C, after nitrogen replacement three times, hydrogen exchange secondary, supplementary pressure is to 2MPa, control temperature is at 60-70 degree, react and substantially do not fall to pressure, after about 2h, reclaim catalyzer.Gained reaction solution concentrated hydrochloric acid is acidified to pH value 3, filters washing and obtains white solid PABA, obtain product 78.8g, yield 96.1%, purity 99.4%(HPLC after drying).
Example three:
150g 4-nitrobenzoic acid and 36g sodium hydroxide, 450g water are mixed with the aqueous solution of 4-nitrobenzoyl acid sodium-salt, join in 1L autoclave, and add 1.5g 5%Pd/C, after nitrogen replacement three times, hydrogen exchange secondary, supplementary pressure is to 2MPa, control temperature is at 60-70 degree, react and substantially do not fall to pressure, after about 2h, reclaim catalyzer.Gained reaction solution concentrated hydrochloric acid is acidified to pH value 3, filters washing and obtains white solid PABA, obtain product 118.5g, yield 96.3%, purity 99.6%(HPLC after drying).
Example four:
200g 4-nitrobenzoic acid and 48g sodium hydroxide, 600g water are mixed with the aqueous solution of 4-nitrobenzoyl acid sodium-salt, join in 1L autoclave, and add 2.0g 5%Pd/C, after nitrogen replacement three times, hydrogen exchange secondary, supplementary pressure is to 2MPa, control temperature is at 60-70 degree, react and substantially do not fall to pressure, after about 2h, reclaim catalyzer.Gained reaction solution concentrated hydrochloric acid is acidified to pH value 3, filters washing and obtains white solid PABA, obtain product 158.5g, yield 96.5%, purity 99.5%(HPLC after drying).
Claims (6)
1. a shortening prepares the method for PABA, it is characterized in that 4-nitrobenzoic acid and equimolar amount prepare the alkali of 4-nitrobenzoate, the aqueous solvent of 3 times of quality is mixed with the aqueous solution of its neutral sodium-salt, 5% Pd/C is catalyzer, control hydrogen pressure at 1-2MPa, temperature is at 60-70 degree, and hydrogenating reduction 2h is to not step-down substantially, its sodium-salt aqueous solution of gained, then acidifying filtration obtains white PABA.
2. a kind of shortening according to claim 1 prepares the method for PABA, and between it is characterized in that the quality of described aqueous solvent is 2 times-10 times of 4-nitrobenzoic acid quality, present method requires that 3 times for good.
3. a kind of shortening according to claim 1 prepares the method for PABA, it is characterized in that the alkali of described preparation 4-nitrobenzoate can for the one in sodium hydroxide, potassium hydroxide, lithium hydroxide.
4. a kind of shortening according to claim 1 prepares the method for PABA, and it is characterized in that described catalyzer can for the one in 5%Pd/C, 10%Pd/C, 7 ‰ Pd/Al2O3,5%Pt/C, 5%Ru/C, present method requires that 5%Pd/C is good.
5. a kind of shortening according to claim 1 prepares the method for PABA, and it is characterized in that the pressure of described hydrogen can between 0.5-6MPa, present method requires that 1-2MPa is good.
6. a kind of shortening according to claim 1 prepares the method for PABA, and it is characterized in that the temperature of described reduction can between 40-100 degree, present method requires that 60-70 degree is good.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410656591.8A CN104326928A (en) | 2014-11-18 | 2014-11-18 | Method for preparing 4-aminobenzoic acid by catalytic hydrogenation |
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| CN201410656591.8A CN104326928A (en) | 2014-11-18 | 2014-11-18 | Method for preparing 4-aminobenzoic acid by catalytic hydrogenation |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106995382A (en) * | 2016-01-25 | 2017-08-01 | 济南和润化工科技有限公司 | A kind of method of catalytic hydrogenation production 3- methyl-PABA |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3882171A (en) * | 1971-04-21 | 1975-05-06 | Universal Oil Prod Co | Hydrogenation of nitrobenzoic acids |
| CN104003892A (en) * | 2014-06-13 | 2014-08-27 | 江苏恒祥化工有限责任公司 | Catalytic hydrogenation preparation method of 3,5-diaminobenzoic acid |
| CN104045574A (en) * | 2014-06-13 | 2014-09-17 | 江苏康恒化工有限公司 | Method for preparing 4-aminobenzoic acid from 4-nitrobenzoic acid by catalytic hydrogenation |
-
2014
- 2014-11-18 CN CN201410656591.8A patent/CN104326928A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3882171A (en) * | 1971-04-21 | 1975-05-06 | Universal Oil Prod Co | Hydrogenation of nitrobenzoic acids |
| CN104003892A (en) * | 2014-06-13 | 2014-08-27 | 江苏恒祥化工有限责任公司 | Catalytic hydrogenation preparation method of 3,5-diaminobenzoic acid |
| CN104045574A (en) * | 2014-06-13 | 2014-09-17 | 江苏康恒化工有限公司 | Method for preparing 4-aminobenzoic acid from 4-nitrobenzoic acid by catalytic hydrogenation |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106995382A (en) * | 2016-01-25 | 2017-08-01 | 济南和润化工科技有限公司 | A kind of method of catalytic hydrogenation production 3- methyl-PABA |
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Application publication date: 20150204 |