CN101066946A - Process of separating methyl pyridine mixture - Google Patents
Process of separating methyl pyridine mixture Download PDFInfo
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- CN101066946A CN101066946A CN 200710041594 CN200710041594A CN101066946A CN 101066946 A CN101066946 A CN 101066946A CN 200710041594 CN200710041594 CN 200710041594 CN 200710041594 A CN200710041594 A CN 200710041594A CN 101066946 A CN101066946 A CN 101066946A
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- entrainer
- alcohol
- mixture
- monohydroxy
- separation method
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Abstract
The present invention relates to process of separating mixture of methyl pyridine isomer and/or homologous compound. The separating process includes the main steps of: normal pressure rectification of the methyl pyridine mixture in the presence of C1-C6 monobasic alcohol water solution as the first azeotropic agent and collecting the fraction comprising the required component and the first azeotropic agent; and the subsequent normal pressure azeotropic rectification of the collected fraction with benzene as the second azeotropic agent to obtain the target product. The present invention can obtain components with purity not lower than 99 wt%, and has cheap material, easy control and low cost.
Description
Technical field
The present invention relates to a kind of main by methyl pyridine isomer or/and the separating mixture that homologue is formed.
Background technology
So far, disclosed separation or/and the method for homologue composition mixture has multiplely, mainly divides three classes by the picoline isomer.The first: adopt adsorption method of separation to separate by the picoline isomer or/and homologue composition mixture (as EP 173440 or U.S.Pat.No.3,064,002 reported method); It two is: chemical transformation, being about to specific compound joins by the picoline isomer or/and in the homologue composition mixture, make the compound and one or more picolines that are added form corresponding derivative, utilize the more segregative characteristics of these derivatives to reach and separate purpose (as U.S.Pat.No.2,516,370 or the described method of JP60214775); It three is: the azeotropic distillation partition method, be about to mainly by the picoline isomer or/and the homologue composition mixture by realize separating (method that is provided as GB 580048) with the entrainer azeotropic distillation.
To sum up, the azeotropic distillation partition method is a kind of separation method that is easy to serialization and mass-producing enforcement, has commercial application value.Used entrainer is a water in the right existing azeotropic distillation isolation technique, cause the boiling point very nearly the same (2 of each azeotrope (each component and water form), the azeotrope mixture cut boiling point of 6-lutidine and water is 95.6 ℃, the boiling point of the azeotrope of 3-picoline and water is 96.7 ℃, the azeotrope cut boiling point of 4-picoline and water is 97 ℃), cause operation and control difficulty, product purity is not high and cost is higher.
Summary of the invention
The objective of the invention is to, the separation method of the low methyl pyridine mixture of a kind of easy handling and control, product purity height and cost (mainly by methyl pyridine isomer or/and homologue form) is provided.
The present inventor is through extensive and deep discovering: adopt C
1～C
6The aqueous solution of monohydroxy-alcohol is entrainer, can increase the gap (disparity between each azeotrope boiling point can expand 4 ℃ to) between the boiling point of each azeotrope in the methyl pyridine mixture (each component and entrainer form), thereby make azeotropic distillation easy handling and control, improved product purity and lowered product cost.
The separation method of the said methyl pyridine mixture of the present invention is characterized in that, the key step of said separation method is: C is being arranged
1～C
6Under the aqueous solution of monohydroxy-alcohol (entrainer 1) existence condition, the 4-methyl pyridine mixture carries out atmospheric distillation, the fraction that collection is made up of required component and entrainer 1 again to the gained fraction, carries out the normal pressure azeotropic distillation with benzene (entrainer 2) and sloughs wherein water and portion C
1～C
6Monohydroxy-alcohol is sloughed C through rectifying again
1～C
6Monohydroxy-alcohol gets target compound.
Wherein: said methyl pyridine mixture is main (as to come from pyridine base cut in the coal tar by methyl pyridine isomer or/and the mixture that homologue is formed, mainly by 3-picoline, 4-picoline and 2, the mixture that the 6-lutidine is formed, each components contents respectively accounts for about 1/3; Said C
1～C
6Monohydroxy-alcohol is meant C
1～C
6Monohydroxy-alcohol in a kind of or two or more mixture.
In an optimal technical scheme of the present invention, said C
1～C
6The concentration of the aqueous solution of monohydroxy-alcohol is 20v/v%～95v/v%, more preferably 80v/v%～90v/v%;
In another optimal technical scheme of the present invention, used entrainer is that concentration is the C of 80v/v%～90v/v%
1～C
3The aqueous solution of monohydroxy-alcohol, wherein C
1～C
3Monohydroxy-alcohol is meant C
1～C
3A kind of or two or more mixture of monohydroxy-alcohol;
In another optimal technical scheme of the present invention, the consumption of entrainer is 5 times～6 times of separated mixture weight.
Embodiment
The separation method of the said methyl pyridine mixture of the present invention comprises the steps:
(1) the pyridine base cut that will come from the coal tar (mainly contains 2 of 34wt%, the 4-picoline of 6-lutidine, 34wt%, the 3-picoline of 30wt% and the unknown impuritie of 2wt%) place rectifying still, add the C of 5 times～6 times of pyridine base cut weight to be separated again
1～C
3The aqueous solution of monohydroxy-alcohol (entrainer 1), carry out normal pressure (1 normal atmosphere) rectifying, collect 2,6-lutidine and used entrainer form azeotrope (when being 80v/v%～90v/v% methanol aqueous solution as used entrainer, then 2, the collection temperature that 6-lutidine and methanol aqueous solution form azeotrope is 62 ℃～63 ℃);
(2) with the still temperature cool to room temperature of rectifying still, add entrainer 1 again, the weight that makes the rectifying still entrainer is 5 times～6 times of mixture weight to be separated, carry out the normal pressure second time (1 normal atmosphere) rectifying, collect 3-picoline and used entrainer and form azeotrope (be that 80v/v%～90v/v% methanol aqueous solution is an example with entrainer equally, the collection temperature of then collecting fraction is 65 ℃～66 ℃);
(3) again the still temperature of rectifying still is chilled to room temperature, add entrainer 1 again, the weight that makes the rectifying still entrainer is 5 times～6 times of mixture weight to be separated, carry out normal pressure (1 normal atmosphere) rectifying for the third time, remove 2 of remnants, 6-lutidine, 3-picoline and unknown impuritie must be rich in the residual solution of 4-picoline;
(4) adopting existing purification process purifying gained cut (is entrainer with benzene earlier promptly, respectively to 2 of gained, 6-lutidine azeotrope, 3-picoline azeotrope and the residual solution that is rich in the 4-picoline are carried out the normal pressure azeotropic distillation and are sloughed wherein moisture (containing solvent), and then solvent is sloughed in rectifying) after target compound.
In the present invention, used rectifying tower can be existing stuffing rectification column, plate distillation column or other form rectifying tower, and its theoretical plate number is 10～25 (preferred 20～25).In rectifying, can adopt gas-chromatography to follow the tracks of, establish the terminal point that different fractions are collected.
Adopt technical scheme of the present invention to separate 3-picoline, the 4-picoline or 2 that obtains, the 6-lutidine, its purity is all more than or equal to 99wt%, raw materials used wide material sources and cheap.Therefore, the invention provides the separation method of the low methyl pyridine mixture of a kind of easy handling and control, product purity height and cost.
The present invention is further elaborated with embodiment below, and its purpose only is better to understand content of the present invention, and unrestricted protection scope of the present invention.
Embodiment 1
100kg is contained 34wt%2, the mixture of 6-lutidine, 34wt%4-picoline, 30wt%3-picoline drops in the still kettle, drop into 360kg methyl alcohol and 40kg water again, as entrainer, heat this solution by rectifying tower (stage number 20) rectifying, under the normal pressure, in the time of 62-63 ℃ cat head effusive be 2, the azeotrope of 6-lutidine and methanol, collect the cut 220kg (gas chromatographic analysis: contain 2 of this boiling point, 6-lutidine 15wt%, methyl alcohol 76.5wt%, water 8.5wt%).
With still kettle temperature cool to room temperature, add 170.1kg methyl alcohol and 18.9kg water again, then carry out rectifying, the collection boiling point is 65-66 ℃ cut 300kg (gas chromatographic analysis: contain 3-picoline 9wt%, methyl alcohol 81.9wt%, water 9.1wt%).
With still kettle temperature cool to room temperature, add 90kg methyl alcohol and 10kg water again, then carry out rectifying, collect 66-68 ℃ cut 100kg (gas chromatographic analysis: contain 2,6-lutidine 1wt%, 3-picoline 1wt%, unknown impuritie 2wt%, methyl alcohol 86.4wt%, water 9.6wt%).
With still kettle temperature cool to room temperature, the interior resistates of still this moment is 4-picoline (34kg) and methanol 32.1kg.
In the cut of each temperature section, add benzene, slough the water (containing methyl alcohol) in the cut by benzene/water/pure ternary azeotropic distillation respectively again, slough methyl alcohol by other rectifying tower again and obtain 2 respectively, 6-lutidine (purity 99%, GC), 4-picoline (purity 99%, GC) and the 3-picoline (purity 99%, GC).
Embodiment 2
100kg is contained 34wt%2, the mixture of 6-lutidine, 34wt%4-picoline, 30wt%3-picoline drops in the still kettle, drop into 400kg 95v/v% ethanol again as entrainer, heat this solution by rectifying tower (stage number 20) rectifying, under the normal pressure, in the time of 69-71 ℃ cat head effusive be 2,6-lutidine and alcoholic acid azeotrope, collect the cut 200kg (gas chromatographic analysis: contain 2 of this boiling point, 6-lutidine 16.5wt%, 95v/v% ethanol 83.5wt%).
With still kettle temperature cool to room temperature, add 150kg 95v/v% aqueous ethanolic solution again, then carry out rectifying, the collection boiling point is 72.5-74 ℃ cut 250kg (gas chromatographic analysis: contain 3-picoline 11.2wt%, 95v/v% ethanol 88.8wt%).
With still kettle temperature cool to room temperature, add 70kg 95v/v% aqueous ethanolic solution again, then carry out rectifying, collect the cut 100kg (gas chromatographic analysis: contain 2,6-lutidine 1wt%, 3-picoline 2wt% of 76-77 ℃ 2, unknown impuritie 2wt%, alcohol 95 wt%).
With still kettle temperature cool to room temperature, the interior resistates of still this moment is 4-picoline (34kg), 95v/v% ethanol 136kg.
The cut of each temperature section passes through still kettle respectively, slough the water (containing ethanol) in the cut by benzene/water/pure ternary azeotropic distillation respectively again, slough ethanol by other rectifying tower again and obtain 2 respectively, 6-lutidine (purity 99%, GC), 4-picoline (purity 99%, GC) and the 3-picoline (purity 99%, GC).
Claims (7)
1, a kind of separation method of methyl pyridine mixture, it is characterized in that, the key step of said separation method is: having under entrainer 1 existence condition, the 4-methyl pyridine mixture carries out atmospheric distillation, the fraction that collection is made up of required component and entrainer 1, to the gained fraction, be entrainer 2 again, carry out getting target compound behind the normal pressure azeotropic distillation with benzene;
Wherein: said methyl pyridine mixture is: main by methyl pyridine isomer or/and the mixture that homologue is formed; Said entrainer 1 is C
1～C
6The aqueous solution of monohydroxy-alcohol, said C
1～C
6Monohydroxy-alcohol is meant C
1～C
6Monohydroxy-alcohol in a kind of or two or more mixture.
2, separation method as claimed in claim 1 is characterized in that, wherein said methyl pyridine mixture comes from the pyridine base cut in the coal tar, and mainly by 3-picoline, 4-picoline and 2, the 6-lutidine is formed.
3, separation method as claimed in claim 1 or 2 is characterized in that, wherein the consumption of entrainer 1 is 5 times～6 times of methyl pyridine mixture weight.
4, separation method as claimed in claim 3 is characterized in that, wherein entrainer 1 is the C of 20v/v%～95v/v% for concentration
1～C
6The monohydroxy-alcohol aqueous solution.
5, separation method as claimed in claim 4 is characterized in that, wherein entrainer 1 is the C of 80v/v%～90v/v% for concentration
1～C
6The monohydroxy-alcohol aqueous solution.
6, separation method as claimed in claim 5 is characterized in that, wherein entrainer 1 is the C of 80v/v%～90v/v% for concentration
1～C
3The aqueous solution of monohydroxy-alcohol, wherein C
1～C
3Monohydroxy-alcohol is meant C
1～C
3A kind of or two or more mixture of monohydroxy-alcohol.
7, separation method as claimed in claim 6 is characterized in that, wherein said entrainer 1 is: concentration is methyl alcohol or the aqueous ethanolic solution of 80v/v%～90v/v%.
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| CN 200710041594 CN101066946A (en) | 2007-06-01 | 2007-06-01 | Process of separating methyl pyridine mixture |
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| CN 200710041594 CN101066946A (en) | 2007-06-01 | 2007-06-01 | Process of separating methyl pyridine mixture |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103044319A (en) * | 2013-01-25 | 2013-04-17 | 山东元利科技股份有限公司 | Method for extracting 2-picoline and 3-picoline from coking crude benzene |
| CN104513195A (en) * | 2014-11-28 | 2015-04-15 | 南京红太阳生物化学有限责任公司 | Aminopyridine isomeride separation method |
| CN104529886A (en) * | 2014-11-29 | 2015-04-22 | 南京红太阳生物化学有限责任公司 | Method for separating mixed aminopyridine through crystallization and rectification coupling technology |
| CN105037251A (en) * | 2015-05-22 | 2015-11-11 | 南京红太阳生物化学有限责任公司 | 3,5-dimethylpyridine purifying method |
| CN114773258A (en) * | 2022-05-10 | 2022-07-22 | 浙江大学杭州国际科创中心 | Separation and purification method of 2, 6-dimethylpyridine |
-
2007
- 2007-06-01 CN CN 200710041594 patent/CN101066946A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103044319A (en) * | 2013-01-25 | 2013-04-17 | 山东元利科技股份有限公司 | Method for extracting 2-picoline and 3-picoline from coking crude benzene |
| CN103044319B (en) * | 2013-01-25 | 2014-09-24 | 山东元利科技股份有限公司 | Method for extracting 2-picoline and 3-picoline from coking crude benzene |
| CN104513195A (en) * | 2014-11-28 | 2015-04-15 | 南京红太阳生物化学有限责任公司 | Aminopyridine isomeride separation method |
| CN104529886A (en) * | 2014-11-29 | 2015-04-22 | 南京红太阳生物化学有限责任公司 | Method for separating mixed aminopyridine through crystallization and rectification coupling technology |
| CN105037251A (en) * | 2015-05-22 | 2015-11-11 | 南京红太阳生物化学有限责任公司 | 3,5-dimethylpyridine purifying method |
| CN114773258A (en) * | 2022-05-10 | 2022-07-22 | 浙江大学杭州国际科创中心 | Separation and purification method of 2, 6-dimethylpyridine |
| CN114773258B (en) * | 2022-05-10 | 2023-08-11 | 浙江大学杭州国际科创中心 | Separation and purification method of 2, 6-lutidine |
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