CN103232338A - Preparation method of phenylacetic acid - Google Patents
Preparation method of phenylacetic acid Download PDFInfo
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- CN103232338A CN103232338A CN2013101375185A CN201310137518A CN103232338A CN 103232338 A CN103232338 A CN 103232338A CN 2013101375185 A CN2013101375185 A CN 2013101375185A CN 201310137518 A CN201310137518 A CN 201310137518A CN 103232338 A CN103232338 A CN 103232338A
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- benzyl cyanide
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- hydrochloric acid
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- acid
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Abstract
The invention discloses a preparation method of phenylacetic acid, which comprises the following steps of: 1) heating benzyl cyanide to 50-100 DEG C, dropwise adding hydrochloric acid to the benzyl cyanide or dropwise adding the molten benzyl cyanide to hydrochloric acid, wherein the molar ratio of the hydrochloric acid to the benzyl cyanide is (1.2-5):1; after dropwise adding, performing a heat preservation reaction for 1-5 hours; and ending the reaction when the mass content of the benzyl cyanide in the reaction system is less than 5%; and 2) performing reduced-pressure distillation for recovering the unreacted benzyl cyanide in the reaction system of the step 1) until the mass content of the benzyl cyanide in the reaction system is less than 0.2%; adding water to the reaction system, and stirring and mixing; cooling for crystallization and performing suction filtration; and washing the obtained crystal with water, and drying to obtain a phenylacetic acid product. According to the preparation method disclosed by the invention, a technology of directly hydrolyzing benzyl cyanide with hydrochloric acid to prepare phenylacetic acid is adopted, few kinds of reactants are used, other organic matters except the raw material benzyl cyanide are not required, the consumption is low, the after-treatment is simple, and both the appearance and quality of the product meet requirements.
Description
Technical field
The present invention relates to the synthesis technical field of toluylic acid, particularly a kind of benzyl cyanide hydrolysis prepares the method for toluylic acid.
Background technology
Benzyl cyanide hydrolysis is to prepare toluylic acid method commonly used, its processing condition are simple relatively, easy and the easy control of operation, be that present domestic research at most also is the most ripe industrialized preparing process, hydrolysis process is divided into two kinds: with highly basic such as sodium hydroxide or potassium hydroxide benzyl cyanide is made sodium phenylacetate for first kind, decolouring back acidifying, crystallization get product; Second kind directly gets toluylic acid with acid hydrolysis, crystallization.Reaction equation is as follows:
1, basic hydrolysis
2, acid hydrolysis
1) sulphuric acid hydrolysis
2) hydrogenchloride adds the tetrahydrofuran (THF) hydrolysis
3) concentrated hydrochloric acid and the hydrolysis of propionic acid mixture (concentrated hydrochloric acid: propionic acid=1:2)
Problem and shortcoming that above-mentioned two kinds of hydrolysis processs exist are:
1) alkali process hydrolysis had not only consumed alkali but also consumption acids, and Atom economy is poor, but also wants by-product ammonia and salt;
2) alkali process hydrolysis generates ammonia, takes organism out of when ammonia is overflowed, and contaminate environment adopts water to absorb or sour the absorption all can't directly be used because organism exceeds standard;
3) sodium phenylacetate solution needs decolouring, produces solid uselessly, and decolorization discharges foul smell, and operating environment is poor;
4) adopt sulphuric acid hydrolysis, the liquid carbonization coking that can induce reaction under the pyroreaction, the aftertreatment difficulty also influences outward appearance and the quality of product, produces that to contain the organism spent acid in a large number difficult;
5) adopt hydrogenchloride/tetrahydrofuran (THF) hydrolysis, need to feed continuously hydrogen chloride gas, need the Separation and Recovery tetrahydrofuran (THF) after reaction finishes, operating process is loaded down with trivial details, and operating environment is relatively poor;
6) use propionic acid and the hydrolysis of concentrated hydrochloric acid mixture, consume lot of organic acids, reclaim difficulty, industrial value is little.
Summary of the invention
In view of this, the invention provides a kind of preparation method of toluylic acid, this method can avoid alkali process hydrolysis to consume shortcomings high, that by-product is many, can avoid the easy carbonization coking of sulfuric acid process hydrolysis, aftertreatment complexity, difficult, the ropy shortcoming of product appearance of waste liquid again, and need not to add other organism except the benzene feedstock acetonitrile, consume lowly, aftertreatment is simple.
The preparation method of toluylic acid of the present invention may further comprise the steps:
1) benzyl cyanide is heated to 50 ~ 100 ℃, dripping hydrochloric acid or the benzyl cyanide of molten state dropped in the hydrochloric acid in the benzyl cyanide then, the mol ratio of hydrochloric acid and benzyl cyanide is 1.2 ~ 5:1, dropwised the back insulation reaction 1 ~ 5 hour, the mass content of benzyl cyanide was less than 5% o'clock termination reaction in the reaction system;
Its chemical equation is:
2) the underpressure distillation recycling step 1) reaction system in unreacted benzyl cyanide, the mass content of benzyl cyanide adds water then less than 0.2% in reaction system in reaction system, stir miscible, crystallisation by cooling then, suction filtration, the gained crystal washes with water, after the drying, obtain the toluylic acid product.
Further, the massfraction of described hydrochloric acid is 15% ~ 37%.
Further, described step 2) in, in the reaction system of step 1), add in the ammoniacal liquor and excessive hydrochloric acid earlier, unreacted benzyl cyanide in the reaction system is reclaimed in underpressure distillation again.
Further, described step 2) excessive hydrochloric acid in the reaction system in, first underpressure distillation recycling step 1) continues underpressure distillation again and reclaims unreacted benzyl cyanide in the reaction system.
Beneficial effect of the present invention is:
1) the present invention adopts hydrochloric acid direct hydrolysis benzyl cyanide to prepare the technology of toluylic acid, compare with concentrated hydrochloric acid mixture hydrolysis process with hydrogenchloride/tetrahydrofuran (THF) hydrolysis or propionic acid, reactant species is few, need not to add other organism except the benzene feedstock acetonitrile, consume lowly, aftertreatment is simple;
2) compare with alkali process hydrolysis, only consume hydrochloric acid and generate ammonium chloride, Atom economy is good, and no ammonia or sodium salt produce, and have avoided follow-up a series of problem;
3) compare with sulphuric acid hydrolysis technology, can not produce the coking phenomenon, hydrolysis is thorough, and excessive hydrochloric acid is recyclable, has avoided producing the big waste acid water of intractability;
4) pilot process dispense with decoloration operation, good operational environment, product appearance and quality all meet the demands.
Embodiment
The preparation method of toluylic acid of the present invention may further comprise the steps:
1) benzyl cyanide is heated to 50 ~ 100 ℃, dripping hydrochloric acid or the benzyl cyanide of molten state dropped in the hydrochloric acid in the benzyl cyanide then, the mol ratio of hydrochloric acid and benzyl cyanide is 1.2 ~ 5:1, dropwised the back insulation reaction 1 ~ 5 hour, the mass content of benzyl cyanide was less than 5% o'clock termination reaction in the reaction system; The massfraction of described hydrochloric acid preferred 15% ~ 37%;
2) the underpressure distillation recycling step 1) reaction system in unreacted benzyl cyanide, the mass content of benzyl cyanide adds water then less than 0.2% in reaction system in reaction system, stir miscible, crystallisation by cooling then, suction filtration, the gained crystal washes with water, after the drying, obtain the toluylic acid product; Also can add in the ammoniacal liquor and excessive hydrochloric acid in the reaction system of step 1) earlier, unreacted benzyl cyanide in the reaction system be reclaimed in underpressure distillation again; All right first underpressure distillation recycling step 1) excessive hydrochloric acid in the reaction system continues underpressure distillation again and reclaims unreacted benzyl cyanide in the reaction system.
To be described in detail an embodiment below.
The preparation of the toluylic acid of present embodiment may further comprise the steps:
1) takes back the benzyl cyanide 236.5g(2mol that adds content 99% in the four-hole boiling flask that flows prolong, thermometer, dropping funnel at 1000mL), adding massfraction in the dropping funnel is 37% hydrochloric acid 493.5g(5mol), the confined reaction system, be heated to 95 ℃, dripping hydrochloric acid dropwises the back 95 ℃ of insulation reaction 5 hours, sampling, HPLC analyzes and learns that the toluylic acid mass content is 94.5% in the reaction system, and the benzyl cyanide mass content is 4.8%, termination reaction;
2) after underpressure distillation steams 200 ml waters, sampling, HPLC analyzes and learns that the toluylic acid mass content is 97.9% in the reaction system, and the benzyl cyanide mass content is 0.15%; In reaction system, add 700mL water then, stir misciblely, be cooled to 30 ℃ of crystallizations then, suction filtration, gained crystal with the washing of 300mL warm water, 30 ~ 40 ℃ of drying under reduced pressure after, obtain white toluylic acid product 249.8g, product purity is 99.3%, yield is 91.2%.
Explanation is at last, above embodiment is only unrestricted in order to technical scheme of the present invention to be described, although by invention has been described with reference to the preferred embodiments of the present invention, but those of ordinary skill in the art is to be understood that, can make various changes to it in the form and details, and not depart from the spirit and scope of the present invention that appended claims limits.
Claims (4)
1. the preparation method of a toluylic acid is characterized in that: may further comprise the steps:
1) benzyl cyanide is heated to 50 ~ 100 ℃, dripping hydrochloric acid or the benzyl cyanide of molten state dropped in the hydrochloric acid in the benzyl cyanide then, the mol ratio of hydrochloric acid and benzyl cyanide is 1.2 ~ 5:1, dropwised the back insulation reaction 1 ~ 5 hour, the mass content of benzyl cyanide was less than 5% o'clock termination reaction in the reaction system;
2) the underpressure distillation recycling step 1) reaction system in unreacted benzyl cyanide, the mass content of benzyl cyanide adds water then less than 0.2% in reaction system in reaction system, stir miscible, crystallisation by cooling then, suction filtration, the gained crystal washes with water, after the drying, obtain the toluylic acid product.
2. the preparation method of toluylic acid according to claim 1, it is characterized in that: the massfraction of described hydrochloric acid is 15% ~ 37%.
3. the preparation method of toluylic acid according to claim 1 and 2 is characterized in that: described step 2), add in the ammoniacal liquor and excessive hydrochloric acid in the reaction system of step 1) earlier, more unreacted benzyl cyanide in the underpressure distillation recovery reaction system.
4. the preparation method of toluylic acid according to claim 1 and 2 is characterized in that: described step 2), first underpressure distillation recycling step 1) reaction system in excessive hydrochloric acid, continue underpressure distillation again and reclaim unreacted benzyl cyanide in the reaction system.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2013101375185A CN103232338A (en) | 2013-04-19 | 2013-04-19 | Preparation method of phenylacetic acid |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2013101375185A CN103232338A (en) | 2013-04-19 | 2013-04-19 | Preparation method of phenylacetic acid |
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| CN103232338A true CN103232338A (en) | 2013-08-07 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104892393A (en) * | 2015-04-29 | 2015-09-09 | 浙江普洛医药科技有限公司 | Preparation method of substituted phenylacetic acid derivative |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2489348A (en) * | 1947-01-15 | 1949-11-29 | Hoffmann La Roche | Production of arylacetic acids and amides |
| CN101161626A (en) * | 2007-11-15 | 2008-04-16 | 浙江大学 | Method for preparing phenylacetic acid by non-catalyzed hydrolysis of benzene acetonitrile in near-critical water medium |
-
2013
- 2013-04-19 CN CN2013101375185A patent/CN103232338A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2489348A (en) * | 1947-01-15 | 1949-11-29 | Hoffmann La Roche | Production of arylacetic acids and amides |
| CN101161626A (en) * | 2007-11-15 | 2008-04-16 | 浙江大学 | Method for preparing phenylacetic acid by non-catalyzed hydrolysis of benzene acetonitrile in near-critical water medium |
Non-Patent Citations (1)
| Title |
|---|
| WILHELM WENNER: ""HYDROLYSIS OF ARYLACETONITRILES"", 《THE JOURNAL OF ORGANIC CHEMISTRY》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104892393A (en) * | 2015-04-29 | 2015-09-09 | 浙江普洛医药科技有限公司 | Preparation method of substituted phenylacetic acid derivative |
| CN104892393B (en) * | 2015-04-29 | 2016-08-24 | 浙江普洛医药科技有限公司 | A kind of preparation method of substituted phenylacetic acid derivant |
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Application publication date: 20130807 |