CN1257888C - Method for synthesizing m-trifluoromethyl benzyl cyanide - Google Patents
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Abstract
The present invention relates to a synthesis method of 3-trifluoromethyl phenylacetonitrile, which comprises the following two reaction steps: a chloromethylation reaction and a cyanidation reaction. In the reaction of the step one, trifluoromethyl benzene, paraformaldehyde and chlorosulfonic acid are used as raw materials reacting with each other under the existence of an inorganic acid to generate 3-trifluoromethyl phenylacetonitrile; in the reaction of the step two, the content of organic phase impurities is controlled below 3% by gas phase chromatographic analysis. The method is favorable for the improvement of reaction yield. The method has the advantages of easy acquirement of raw materials for production, simple operation, convenient control, high reaction yield, low production cost, environmental pollution reduction, etc. The present invention is a synthesis method suitable for industrialized production.
Description
Technical Field
The invention relates to a synthetic method of an organic fluorine compound, in particular to a synthetic method of m-trifluoromethyl benzyl cyanide.
Background
The meta-trifluoromethyl benzyl cyanide belongs to a fluorinated aromatic chemical product. In the field of pesticide synthesis, the compound can be used for preparing herbicides; in the field of medicine production, can be used for synthesizing antibacterial drugs, weight-reducing drugs and coronary vasodilators.
The prior art reports that the following methods for synthesizing m-trifluoromethyl phenylacetonitrile mainly exist.
In 1979, The synthesis method of m-trifluoromethyl phenylacetonitrile reported in The U.S. Pat. No. 4, 4,144,265 of The Dow Chemical Company, uses trifluoromethyl benzene, chloromethyl methyl ether and chlorosulfonic acid as raw materials to prepare m-trifluoromethyl chloromethyl benzene, and then reacts The m-trifluoromethyl chloromethyl benzene with sodium cyanide aqueous solution under The action of quaternary ammonium salt to prepare m-trifluoromethyl phenylacetonitrile. Chloromethyl methyl ether is low in boiling point, volatile, pungent and smelly, is a strong carcinogen, belongs to a product prohibited by industrial production issued in China, and is not suitable for large-scale production.
In 1989, German patent 3,717,434 published by Degussa Aktiengesellschaft reports a method for synthesizing m-trifluoromethylphenylacetonitrile, which comprises reacting trifluoromethylbenzene with chlorocyanogen (ClCN) gas at a high temperature of 600-700 ℃ to directly prepare the m-trifluoromethylphenylacetonitrile. Although the one-step reaction can shorten the process flow, the virulent chlorocyanogen needs to be synthesized on site, and the production is not facilitated at the high temperature of 600-700 ℃.
The synthesis of m-trifluoromethylphenylacetonitrile reported in U.S. Pat. No. 4, 4,966,988 by the method of 1990, is carried out by introducing chlorine gas into pyridine solvent to obtain α 0-trichloro-m-xylene, reacting α 1, α 2, α 3-trichloro-m-xylene with hexachloroethane in tetrachloroethylene in the presence of quaternary ammonium salt and aqueous solution of potassium hydroxide to obtain α '-tetrachloro-m-xylene, fluorinating α' -tetrachloro-m-xylene with Hydrogen Fluoride (HF) gas to obtain m-trifluoromethylchloromethylbenzene, and reacting m-trifluoromethylchloromethylbenzene with aqueous solution of sodium cyanide in the presence of quaternary ammonium salt in acetonitrile solvent to obtain m-trifluoromethylphenylacetonitrile.
Disclosure of Invention
The invention provides a method for synthesizing m-trifluoromethyl benzyl cyanide, which comprises two steps, wherein in the first step, a chloromethylation reaction is carried out to synthesize m-trifluoromethyl chloromethyl benzene; the second step of cyanidation reaction generates m-trifluoromethyl phenylacetonitrile.
The reaction formula for the two steps is shown below:
2.
the first step of chloromethylation reaction is to react trifluoromethyl benzene, paraformaldehyde and chlorosulfonic acid as raw materials in the presence of catalyst inorganic acid to generate m-trifluoromethyl chloromethyl benzene, wherein the molar ratio of the raw materials is 1: 1-1.7: 1-1.3.
Inorganic acid is added as a catalyst, so that paraformaldehyde can be dissolved in trifluoromethyl benzene, the contact area between molecules is increased, and the reaction speed is accelerated; the strong acidity can also enable the acidic gas generated in the reaction to rapidly escape from the system, reduce side reactions and improve the reaction yield. The inorganic acid is generally selected from sulfuric acid with the concentration range of 60-90%, and the dosage of the inorganic acid is 20-35% of that of the trifluoromethyl benzene
After adding the trifluoromethyl benzene, the paraformaldehyde and the inorganic acid catalyst, dropwise adding chlorosulfonic acid, controlling the temperature of the materials to be 10-30 ℃, reacting for 1-2 hours at 35-55 ℃ after dropwise adding, standing for layering, removing an acid water phase, washing with water, and neutralizing with a 5-15% sodium hydroxide solution until the pH is 6-7. Then, carrying out reduced pressure distillation at the vacuum degree of 0.09-0.099 MPa, and collecting the front fraction (unreacted trifluoromethyl benzene which can be used indiscriminately) at the temperature of 50-55 ℃. And collecting the fraction at 75-80 ℃ to obtain the m-trifluoromethyl chloromethyl benzene, wherein the content of the m-trifluoromethyl chloromethyl benzene is more than 97%, and the yield is 65-67% (based on the trifluoromethyl benzene). The residual feed liquid can be recycled to prepare 3, 3' -bis (trifluoromethyl) phenylmethane as a byproduct, and the recycling amount is about 15-20% of the trifluoromethyl benzene.
The second step of cyanidation is to react m-trifluoromethyl chloromethyl benzene with sodium cyanide aqua in the presence of phase transfer catalyst to produce m-trifluoromethyl benzyl cyanide. The reaction molar ratio of m-trifluoromethyl chloromethyl benzene to sodium cyanide in the reaction is 1: 1-1.5. In the production, the sodium cyanide is preferably 20-35% aqueous solution, and the reaction is carried out at 45-60 ℃ for 10-16 hours.
A small amount of phase transfer catalyst (such as tetrabutylammonium bromide) is added in order to make the water phase and the organic phase fully contact and react to accelerate the reaction speed, but the side reaction can also be generated while the main reaction is accelerated, and the reaction yield is reduced by the generation of some impurities. To improve the reaction yield. According to our experiments, the impurity content is higher than 3%, and the impurity has a sudden and abrupt process. The mutation process can be weakened and inhibited through quality control, and once the generation speed of impurities is found to be increased, the reaction temperature is reduced, so that the main reaction speed and the auxiliary reaction speed are both reduced. Therefore, to prevent this mutation process, we strictly controlled the impurity content below 3%.
The amount of the phase transfer catalyst added is generally 1.0 to 1.5% by weight based on m-trifluoromethyl chloromethyl benzene.
After the reaction is finished, removing the water phase by layering, washing with clear water, and carrying out reduced pressure distillation to obtain a trifluoromethyl phenylacetonitrile product with the total content of 99.1-99.5%, wherein: the content of m-trifluoromethyl phenylacetonitrile reaches 94.4-94.6%, the content of o-trifluoromethyl phenylacetonitrile is less than 1.5%, the content of p-trifluoromethyl phenylacetonitrile is less than 3.5%, and the reaction yield is 90-92% (calculated by m-trifluoromethyl chloromethyl benzene).
The invention relates to a process for synthesizing m-trifluoromethyl phenylacetonitrile, which takes trifluoromethyl benzene, paraformaldehyde and chlorosulfonic acid as raw materials to carry out chloromethylation reaction in the presence of a sulfuric acid catalyst to generate m-trifluoromethyl chloromethylphenyl, and the yield can reach 65-67%. Then, in the presence of a quaternary ammonium salt phase transfer catalyst, carrying out a cyanidation reaction on m-trifluoromethyl chloromethyl benzene and a sodium cyanide aqueous solution, tracking by adopting gas chromatography analysis, controlling organic phase impurities to enable the impurity content to be lower than 3%, wherein the total content of the prepared product trifluoromethyl phenylacetonitrile can reach 99.1-99.5%, the m-trifluoromethyl phenylacetonitrile content can reach 94.4-94.6%, the o-trifluoromethyl phenylacetonitrile content is lower than 1.5%, the p-trifluoromethyl phenylacetonitrile content is lower than 3.5%, the second-step reaction yield can reach 90-92%, and the second-step reaction total yield is 59-62%. The yield and the total yield of the two-step reaction are higher than those of the prior art.
The synthesis method of m-trifluoromethyl benzyl cyanide of the invention has the advantages that the raw materials for producing trifluoromethyl benzene, formaldehyde, chlorosulfonic acid and the like are sold in markets, thereby avoiding the use of volatile highly toxic raw materials such as chloromethyl methyl ether, chlorocyanogen and the like and also avoiding the use of harsh conditions such as high-temperature equipment and the like. The method adds a sulfuric acid catalyst in the first step of reaction, controls the content of organic phase impurities to be lower than 3% by adopting gas chromatography analysis in the second step of reaction, accelerates the reaction speed and improves the reaction yield. Referring to the results shown in the following synthetic examples and comparative examples, the yield of the comparative example was lower than that of the synthetic example. For example, example 5 shows that in the case where sulfuric acid is not added in the first reaction step, although the reaction time is increased to 12 hours (example 1 is 2 hours) at 40 ℃, the yield is still lower than that of example 1. If the reaction time is 2 hours, the yield is lower. In addition, the by-product 3, 3' -bis (trifluoromethyl) phenylmethane generated in the first reaction step is also a useful fluorine-containing aromatic chemical product, and can be recycled, so that the production cost is reduced. Especially, the used raw material-paraformaldehyde is solid particles, which is convenient for storage and transportation, simple in production operation and convenient for control, and the method has the characteristics of high reaction yield and low production cost, so that the method is a synthetic method suitable for industrial production.
Detailed Description
The invention is further illustrated by the following examples, without limiting the scope of the invention.
EXAMPLE 1 Synthesis of m-trifluoromethylphenylacetonitrile
100 kg of 85% sulfuric acid, 298 kg of 98% trifluoromethylbenzene (2.00kmol) and 90 kg of 98% trioxymethylene (2.94kmol, melting point 64-67 ℃) were added to a reaction vessel, and 265 kg of 98% chlorosulfonic acid (2.23kmol) was added dropwise thereto at 15 ℃ to 25 ℃. After the dropwise addition, the reaction is carried out for 2 hours at 40 ℃, an acid water phase is separated after standing, the reaction solution is washed twice by clean water, the reaction solution is neutralized to PH6 by 10% sodium hydroxide solution, reduced pressure distillation is carried out at the vacuum degree of 0.092MPa, 110 kg of fraction trifluoromethyl benzene with the content of 96% (applicable) is collected before 50-55 ℃, and then fraction with the temperature of 75-80 ℃ is collected at the vacuum degree of 0.099MPa, so that 170 kg of m-trifluoromethyl chloromethyl benzene with the content of 97.5% is obtained, and the yield is 66.73% (calculated by the content of the trifluoromethyl benzene). The remaining liquid can be used for preparing 28 kg of 3, 3' -bis (trifluoromethyl) phenylmethane.
170 kg of prepared 97.5% m-trifluoromethyl chloromethyl benzene (0.85kmol), 165 kg of 33% sodium cyanide aqueous solution (1.11kmol) and 2 kg of tetrabutylammonium bromide are added into a reaction pot for cyanidation reaction, the reaction is carried out for 12 hours at 45 ℃, the mass tracking is carried out by gas chromatography analysis, the organic phase impurity is controlled to be less than 3%, the water phase is separated, the washing is carried out twice by clear water, the reduced pressure distillation is carried out at the vacuum degree of 0.099MPa, the fraction at 94-97 ℃ is collected, 153 kg of trifluoromethyl benzyl cyanide products are obtained, the total content reaches 99.5%, the content of the m-trifluoromethyl benzyl cyanide reaches 94.6%, the content of the o-trifluoromethyl benzyl cyanide reaches 1.5%, the content of the p-trifluoromethyl benzyl cyanide reaches 3.4%, and the reaction yield reaches 91.81% (calculated on the m-trifluoromethyl chloromethyl benzene).
The total yield was 61.26%.
The spectral analysis of the product m-trifluoromethylphenylacetonitrile was as follows:
characteristic frequency (cm) of infrared absorption spectrum-1)：2254，1600，1495，1454，1336
The absorption peak of each functional group in the infrared spectrogram is consistent with that of astandard spectrogram (Aldrich F1, 335-5);
mass spectrometry analysis:
mass to charge ratio (m/z) 11618515916618689165117
Absorption rate (% RA) 10042.8426.6615.4212.5911.3110.239.83
The mass spectrum is consistent with a standard spectrum (Library Search, C: \ Database \ NIST98.L),
the EI low-resolution mass spectrum has a molecular ion peak of 185, which proves that the molecular weight is 185,
EI high resolution mass spectrum proves that the molecular formula is C9H6F3N。
EXAMPLE 2 Synthesis of m-trifluoromethylphenylacetonitrile
100 kg of 75% sulfuric acid, 298 kg of 98% trifluoromethylbenzene (2.00kmol) and 90 kg of 98% paraformaldehyde (2.94kmol, melting point 121-. After the dropwise addition, the reaction is carried out for 1 hour at 55 ℃, an acid water phase is separated after standing, the reaction solution is washed twice by clean water, the reaction solution is neutralized to PH6 by 10% sodium hydroxide solution, pressure reduction distillation is carried out at the vacuum degree of 0.092MPa, 114 kg of fraction trifluoromethyl benzene with the content of 96.5% (applicable) is collected before 50-55 ℃, 164 kg of fraction m-trifluoromethyl chloromethyl benzene with the content of 97.1% is collected at the vacuum degree of 0.099MPa, and the yield is 65.7% (calculated by the trifluoromethyl benzene). The remaining liquid can be used for preparing 29 kg of 3, 3' -bis (trifluoromethyl) phenylmethane.
164 kg of prepared 97.1% m-trifluoromethyl chloromethyl benzene (0.82kmol), 187 kg of 30% sodium cyanide aqueous solution (1.14kmol) and 2 kg of tetrabutylammonium bromide are added into a reaction pot for cyanidation reaction, the reactionis carried out for 10 hours at 55 ℃, the mass tracking is carried out by gas chromatography analysis, the organic phase impurity is controlled to be less than 3%, the water phase is separated, the washing is carried out twice by clear water, the reduced pressure distillation is carried out at the vacuum degree of 0.099MPa, the fraction at 94-97 ℃ is collected, 145 kg of trifluoromethyl benzyl cyanide is obtained, the total content reaches 99.1%, the content of the m-trifluoromethyl benzyl cyanide reaches 94.4%, the content of the o-trifluoromethyl benzyl cyanide reaches 1.4%, the content of the p-trifluoromethyl benzyl cyanide reaches 3.3%, and the reaction yield reaches 90.0% (based on the m-trifluoromethyl chloromethyl benzene).
The overall yield was 59.1%.
Example 3 comparative example corresponding to the second cyanation of example 1
170 kg of 97.5% m-trifluoromethyl chloromethyl benzene (0.85kmols), 165 kg of 33% sodium cyanide aqueous solution (1.11kmols) and 2 kg of tetrabutylammonium bromide are added into a reaction kettle for cyanidation reaction, the reaction is carried out for 12 hours at 45 ℃ without mass tracking, the content of organic phase impurities is 5.5%, water phase is removed, the reaction product is washed twice by clean water, reduced pressure distillation is carried out at the vacuum degree of 0.099MPa, 94-97 ℃ fractions are collected, 146 kg of trifluoromethyl benzyl cyanide products are obtained, the total content reaches 98.7%, the content of intermediate-trifluoromethyl benzyl cyanide reaches 94.0%, the content of o-trifluoromethyl benzyl cyanide reaches 1.4%, the content of p-trifluoromethyl benzyl cyanide reaches 3.3%, and the reaction yield is 87.05% (calculated on the m-trifluoromethyl chloromethyl benzene).
Example 4 corresponding comparative example of the second cyanidation of example 2
164 kg of 97.1% m-trifluoromethyl chloromethyl benzene (0.82kmol), 187 kg of 30% sodium cyanide aqueous solution (1.14kmol) and 2 kg of tetrabutylammonium bromide are added into a reaction pot for cyanidation, the reaction is carried out at 55 ℃ for 10 hours without mass tracking, the content of impurities in an organic phase is 10.1%, a water phase is removed, the reaction is washed twice with clear water, reduced pressure distillation is carried out at the vacuum degree of 0.099MPa, fractions at 94-97 ℃ are collected to obtain 125 kg of trifluoromethyl benzyl cyanide products, the total content reaches 98.0%, the content of the m-trifluoromethyl benzyl cyanide reaches 94.0%, the content of the o-trifluoromethyl benzyl cyanide reaches 1.4%, the content of the p-trifluoromethyl benzyl cyanide reaches 3.6%, and the reaction yield is 77.38% (based on the m-trifluoromethyl benzene chloromethyl).
Example 5 comparative example corresponding to the first chloromethylation reaction of example 1
298 kg of 98% trifluoromethylbenzene (2.00kmol) and 90 kg of 98% trioxymethylene (2.94kmol) were added to a reaction vessel, and 265 kg of 98% chlorosulfonic acid (2.15kmol) was added dropwise thereto at 15 ℃ to 25 ℃. After the dropwise addition, the reaction is carried out for 12 hours at 40 ℃, an acid water phase is separated after standing, the reaction solution is washed twice by clean water, the reaction solution is neutralized to PH6 by 10% sodium hydroxide solution, reduced pressure distillation is carried out under the vacuum degree of 0.092MPa, 111 kg of fraction trifluoromethyl benzene with the content of 96.5% (applicable) is collected before 50-55 ℃, reduced pressure distillation is carried out under the vacuum degree of 0.099MPa, the fraction with the temperature of 75-80 ℃ is collected, 125 kg of m-trifluoromethyl chloromethyl benzene with the content of 97.5% is obtained, and the yield is 50.74% (calculated by the trifluoromethyl benzene).
Claims (3)
1. A synthetic method of m-trifluoromethyl benzyl cyanide comprises two steps of reaction, wherein the first step of reaction is used for synthesizing m-trifluoromethyl chloromethyl benzene, and the second step of reaction is used for carrying out cyanidation reaction on the m-trifluoromethyl chloromethyl benzene and a sodium cyanide aqueous solution under the action of a phase transfer catalyst quaternary ammonium salt to generate the m-trifluoromethyl benzyl cyanide, and is characterized in that the first step of reaction is carried out by taking trifluoromethyl benzene, paraformaldehyde and chlorosulfonic acid as raw materials and reacting in the presence of a catalyst inorganic acid to generate the m-trifluoromethyl chloromethyl benzene, wherein the molar ratio of the raw materials is 1: 1-1.7: 1-1.3, the reaction temperature is 35-55 ℃, the reaction time is 1-2 hours, and the using amount of the inorganic acid is 20-35% of the amount of the trifluoromethyl benzene; in the second cyanidation step, the content of organic phase impurities is controlled to be less than 3%.
2. The method of claim 1, wherein the mineral acid in the first step is sulfuric acid.
3. The synthesis process according to claim 1, wherein the second reaction step uses gas chromatography to control the content of impurities in the organic phase to less than 3%.
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Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104447402B (en) * | 2014-11-27 | 2016-05-11 | 上海赫腾精细化工有限公司 | The preparation method of m-trifluoromethyl benzene acetonitrile |
| CN104478654A (en) * | 2014-12-26 | 2015-04-01 | 上海赫腾精细化工有限公司 | Preparation method of alpha-trifluoro-m-xylene |
| CN105130846A (en) * | 2015-07-27 | 2015-12-09 | 湖北仙盛科技有限公司 | Methyl 3-(cyanomethyl)benzoate synthetic method |
| CN106349006B (en) * | 2016-08-26 | 2019-02-05 | 大连奇凯医药科技有限公司 | The preparation method of 3- trifluoromethyl benzyl cyanide |
| CN108383744B (en) * | 2018-02-11 | 2021-05-11 | 浙江工业大学 | Preparation method of 2, 6-dimethyl-tyrosine |
| CN113200815B (en) * | 2021-04-29 | 2023-09-29 | 爱斯特（成都）生物制药股份有限公司 | Method for synthesizing m-trifluoromethyl benzyl chloride through continuous flow |
| CN113666817A (en) * | 2021-08-30 | 2021-11-19 | 宁夏常晟药业有限公司 | Synthesis method of 1-phenyl-3- (3-trifluoromethylphenyl) -2-acetone |
| CN116478066A (en) * | 2023-04-27 | 2023-07-25 | 宁夏思科达生物科技有限公司 | Production process of m-trifluoromethyl benzyl cyanide |
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