CN111072496A - Method for removing N-methylaniline impurities - Google Patents
Method for removing N-methylaniline impurities Download PDFInfo
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- CN111072496A CN111072496A CN201911364699.9A CN201911364699A CN111072496A CN 111072496 A CN111072496 A CN 111072496A CN 201911364699 A CN201911364699 A CN 201911364699A CN 111072496 A CN111072496 A CN 111072496A
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- methylaniline
- impurities
- dimethylaniline
- nitrite
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
- C07C209/82—Purification; Separation; Stabilisation; Use of additives
- C07C209/84—Purification
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- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a method for removing N-methylaniline impurities, which comprises three steps of analyzing the content of N, N-dimethylaniline in N-methylaniline, adding nitrite into the N-methylaniline, stirring for reaction and filtering to remove impurities. The method for removing the N-methylaniline impurities can effectively separate a small amount of N, N-dimethylaniline in the N-methylaniline, thereby greatly improving the purity of the N-methylaniline product; the method has the advantages of simple operation steps, less equipment investment and high economical and practical properties, and is suitable for industrial production and purification of N-methylaniline.
Description
Technical Field
The invention relates to a method for chemically removing impurities, in particular to a method for removing N-methylaniline impurities.
Background
N-methylaniline is an important intermediate in chemical production of pesticides, dyes, medicines, rubber and the like, and has wide application. It is synthesized by aniline and methanol through gas phase reaction under the catalysis of catalyst, and is separated by a rectifying tower. The purity of the N-methylaniline product obtained by the method is about 98.5 percent, and the N-methylaniline product contains a small amount of N, N-dimethylaniline impurities. Since the N-methylaniline product contains a small amount of N, N-dimethylaniline impurities, the N-methylaniline product is easy to discolor after being stored for a long time and has irritant odor, so how to remove the small amount of N, N-dimethylaniline impurities in the N-methylaniline product is more and more important.
At present, the method for separating N-methylaniline and N, N-dimethylaniline is mainly rectification, but the amount of N, N-dimethylaniline in an N-methylaniline product is small, the investment of rectification equipment is large, and the separation precision of a rectification tower cannot achieve the effect of completely removing a small amount of N, N-dimethylaniline impurities in the N-methylaniline product; in addition, other methods for removing a small amount of N, N-dimethylaniline impurities in N-methylaniline have not been reported in the literature.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a method for removing N-methylaniline impurities.
In order to achieve the purpose, the technical scheme of the invention is to design a method for removing N-methylaniline impurities, which comprises the following steps:
s1: analyzing the content of N, N-dimethylaniline in the N-methylaniline;
s2: adding a certain amount of nitrite compound into a certain amount of N-methylaniline, stirring and heating to 40-60 ℃, and reacting for 0.5-1 h at constant temperature to obtain a reaction mixed solution;
s3: filtering the reaction mixed solution to obtain a pure product of the N-methylaniline and solid impurities.
Preferably, in step S1, the content of N, N-dimethylaniline in N-methylaniline is quantitatively analyzed by gas or liquid chromatography.
In a preferred embodiment, in step S2, the nitrite compound is one of sodium nitrite and potassium nitrite.
Further preferably, in the step S2, the mass of the sodium nitrite or the potassium nitrite is 1 to 1.2 times of the mass of the N, N-dimethylaniline in the N-methylaniline.
The principle of removing a small amount of N, N-dimethylaniline in N-methylaniline is as follows: adding nitrite into N-methylaniline, stirring, heating and keeping the temperature constant for 0.5-1 h, wherein a small amount of N, N-dimethylaniline in the N-methylaniline reacts with the nitrite to generate precipitate impurities (4-nitroso-N, N-dimethylaniline); and removing impurities of the precipitate by filtration to obtain a filtrate, namely the purified N-methylaniline.
The invention has the advantages and beneficial effects that:
the method for removing the N-methylaniline impurities can effectively separate a small amount of N, N-dimethylaniline in the N-methylaniline, thereby greatly improving the purity of the N-methylaniline product; the method has the advantages of simple operation steps, less equipment investment and high economical and practical properties, and is suitable for industrial production and purification of N-methylaniline.
Detailed Description
The following further describes embodiments of the present invention with reference to examples. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
Example 1
Analyzing the mass content of the N-methylaniline in the crude product of the N-methylaniline to be 98 percent by utilizing a gas chromatography; 50g N-methylaniline crude product was added to 4 100mL flasks, each flask containing 2% by weight (8.25mmol) of N, N-dimethylaniline, of which 1#A blank sample is obtained; 2#0.570g (8.26mmol) of sodium nitrite is added; 3# 0.627g (9.09mmol) of sodium nitrite was added; 4# 0.684g (9.91mmol) of sodium nitrite are added; stirring each flask for 5min, heating to 40-50 ℃ and keeping the constant temperature for 1 hour to generate precipitates; the precipitate was filtered and analyzed by gas chromatography 1#Blank samples and 2#～4#The mass contents of N-methylaniline and N, N-dimethylaniline in the filtrate, and the analysis results are shown in Table 1.
Table 1 example 1#～4#Results of experimental data
Example 2
Analyzing the mass content of the N-methylaniline in the crude product of the N-methylaniline to be 97 percent by utilizing a gas chromatography; 50g N-methylaniline crude product was added to 4 100mL flasks, each flask containing 3% by mass (12.38mmol) of N, N-dimethylaniline, of which 1#A blank sample is obtained; 2#1.066g (12.53mmol) of potassium nitrite are added; 1.173g (13.78mmol) of potassium nitrite was added to # 3; 4# 1.279g (15.03mmol) of potassium nitrite were added; stirring each flask for 5min, heating to 50-60 ℃, keeping the constant temperature for 0.5 h, and generating precipitates; for treatingThe precipitate was filtered off and analyzed by gas chromatography 1#Blank samples and 2#～4#The mass contents of N-methylaniline and N, N-dimethylaniline in the filtrate, and the analysis results are shown in Table 2.
Table 2 example 1#～4#Results of experimental data
The data in table 1 or table 2 in example 1 or example 2 show that the purity of the N-methylaniline product is greatly improved after the crude N-methylaniline product is added with sodium nitrate or potassium nitrate according to the method of the invention, heated, stirred, filtered and purified, and the method of the invention has simple operation steps and high economical and practical properties, thus achieving the purpose of the invention.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the technical principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (4)
1. A method for removing N-methylaniline impurities is characterized by comprising the following steps:
s1: analyzing the content of N, N-dimethylaniline in the N-methylaniline;
s2: adding a certain amount of nitrite compound into a certain amount of N-methylaniline, stirring and heating to 40-60 ℃, and reacting for 0.5-1 h at constant temperature to obtain a reaction mixed solution;
s3: filtering the reaction mixed solution to obtain a pure product of the N-methylaniline and solid impurities.
2. The method for removing N-methylaniline impurities as claimed in claim 1, wherein in the step S1, the content of N, N-dimethylaniline in N-methylaniline is quantitatively analyzed by gas chromatography or liquid chromatography.
3. The method for removing N-methylaniline impurities as in claim 1, wherein in the step S2, the nitrite compound is one of sodium nitrite and potassium nitrite.
4. The method for removing N-methylaniline impurities as claimed in claim 3, wherein in the step S2, the mass of the sodium nitrite or the potassium nitrite is 1-1.2 times of the mass of the N, N-dimethylaniline in the N-methylaniline.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911364699.9A CN111072496A (en) | 2019-12-26 | 2019-12-26 | Method for removing N-methylaniline impurities |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911364699.9A CN111072496A (en) | 2019-12-26 | 2019-12-26 | Method for removing N-methylaniline impurities |
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| CN201911364699.9A Pending CN111072496A (en) | 2019-12-26 | 2019-12-26 | Method for removing N-methylaniline impurities |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101585772A (en) * | 2009-06-09 | 2009-11-25 | 台州市知青化工有限公司 | Method of preparing p-nitrosoaniline derivatives |
| CN101607916A (en) * | 2008-06-19 | 2009-12-23 | 天津市化学试剂研究所 | A kind of to amino-N, the preparation method of accelerine hydrochloride |
| CN105130926A (en) * | 2015-07-31 | 2015-12-09 | 江苏恒润制药有限公司 | Preparation method of methylene blue |
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2019
- 2019-12-26 CN CN201911364699.9A patent/CN111072496A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101607916A (en) * | 2008-06-19 | 2009-12-23 | 天津市化学试剂研究所 | A kind of to amino-N, the preparation method of accelerine hydrochloride |
| CN101585772A (en) * | 2009-06-09 | 2009-11-25 | 台州市知青化工有限公司 | Method of preparing p-nitrosoaniline derivatives |
| CN105130926A (en) * | 2015-07-31 | 2015-12-09 | 江苏恒润制药有限公司 | Preparation method of methylene blue |
Non-Patent Citations (1)
| Title |
|---|
| 轻工院校《有机化学》编写组: "《有机化学》", 30 June 1988 * |
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Application publication date: 20200428 |