CN109851478B - Dibenzyl alcohol extraction purification method - Google Patents
Dibenzyl alcohol extraction purification method Download PDFInfo
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Abstract
The invention provides a method for efficiently separating dibenzyl alcohol in a dibenzyl alcohol production process. And extracting the product dibenzyl alcohol after the reaction to an organic phase in a solvent extraction mode, and then purifying the dibenzyl alcohol by using the same solvent crystallization mode. The method solves the following technical problems: 1. in the water evaporation process of the reacted crude product, because the alkaline hydrolysis reaction needs to add water with 15 times of mass equivalent of the raw material of the dichlorobenzyl to ensure the full hydrolysis of the dichlorobenzyl, and 65-75% of the water needs to be evaporated after the alkaline hydrolysis reaction is finished, the specific heat of the water is large, the whole process consumes too long time and consumes huge energy, and the top pipeline is blocked due to the fact that the material is taken out by water vapor to be cooled and crystallized at the top part; 2. the materials are remained in the salt water after water evaporation, the salt water can not be recycled, and the material consumption is large; 3. the two-step crystallization step is complicated and is not beneficial to the technical problem of large-scale production.
Description
Technical Field
The invention relates to a method for purifying an organic raw material, in particular to a method for purifying dibenzyl alcohol.
Background
In the field of materials science, dibenzyl alcohol is an important organic chemical functional block. The chemical structure of the benzene ring of dibenzyl alcohol (o-xylene glycol, m-xylene glycol and p-xylene glycol are collectively called) is very suitable for synthesizing high-molecular or long-chain functional materials by two benzyl hydroxyl skeletons. Therefore, the dibenzyl alcohol has better application in the fields of some high-end functional materials. Among them, o-xylene glycol is an important organic fine chemical and intermediate, and mainly used as a resin additive. Terephthalyl alcohol is an important chemical intermediate building block and has unique characteristics in the high-end material field.
Due to the structural characteristics of the dibenzyl alcohol, the 1, 2 or 1, 3 or 1, 4 position on the benzene ring is benzyl hydroxyl, and the dibenzyl alcohol has stronger hydrophilic performance, so the dibenzyl alcohol has better solubility in water. And because the good hydrophilic characteristics brought by the two benzyl hydroxyl groups on the backbone of the dibenzyl alcohol cause that the dibenzyl alcohol is difficult to separate and purify from saline water after the synthesis is finished, the existing industrial production process generates a large amount of waste water and waste salt and takes a long time. Due to the restriction of the existing production process, the yield of the dibenzyl alcohol is small, the cost is high, the sale price of one ton of p-xylene glycol on the market at present exceeds 10 ten thousand, and the wider application of the dibenzyl alcohol in the downstream field is limited to a great extent.
Taking the synthesis method of terephthalyl alcohol as an example, the main methods for synthesizing terephthalyl alcohol at present are the hydrogenation method of terephthalic acid and the hydrolysis method of p-dichlorobenzyl. The terephthalic acid hydrogenation method uses terephthalic acid as a raw material, but two carboxylic acids on the terephthalyl alcohol are hydrogenated into alcohol, so that a noble metal catalyst is needed to realize catalytic hydrogenation under higher pressure, and the huge investment brought by the investment of hydrogenation equipment and the huge cost of the catalyst is in conflict with the current market demand of very small terephthalyl alcohol, so that no industrial apparatus for synthesizing the terephthalyl alcohol by the terephthalic acid hydrogenation method exists at present. Another process is the hydrolysis of dichlorobenzyl, the synthesis of which is similar to that reported in patent ZL 201010568813.2.
The method ZL 201010568813.2 is characterized in that o-dichlorobenzyl is used as a raw material, sodium carbonate is used as alkali, water with 15 times of raw material equivalent is stirred and heated to carry out alkaline hydrolysis on the o-dichlorobenzyl to generate a crude o-xylene glycol product. The reaction crude product phthalic alcohol is dissolved in water due to the hydrophilic action of the two hydroxyl groups on phthalic alcohol, and the crude product does not separate from the salt water. In the process, because water with the weight 15 times that of o-dichlorobenzyl is needed to ensure the full hydrolysis of the o-dichlorobenzyl, 65-75% of water is distilled out in the water distillation process, the upper layer liquid material is poured out when the water is hot, and the liquid material is cooled and crystallized to obtain the o-xylene glycol crude product. And crystallizing the crude product by using water to obtain the finished product of the o-xylene glycol. The process solves the problem that the o-xylene glycol is not layered when dissolved in water, firstly, water is distilled, then liquid is separated when the solution is hot, the separation of the o-xylene glycol and saline water is realized, and then, the refining of a crude product o-xylene glycol is realized by means of cooling crystallization and water crystallization, so that a finished product o-xylene glycol is obtained.
Based on the above-mentioned method for producing o-xylene glycol (ZL 201010568813.2) developed by my company, we have conducted large-scale industrial production and accumulated abundant production experience. However, this method also has some inconveniences in production: 1. in the process of evaporating water from the crude product after reaction, the specific heat of water is large, the whole process consumes too long time and consumes huge energy, and the top pipeline is blocked frequently because the material is brought out of the top of the equipment by water vapor and cooled and crystallized; 2. the materials are remained in the salt water after water evaporation, the salt water can not be recycled, and the material consumption is large; 3. the two-step crystallization step is relatively complicated and is not suitable for large-scale production.
Based on the technical problems, the invention provides a method for efficiently separating dibenzyl alcohol in a dibenzyl alcohol production process. Selecting a proper solvent, extracting the product dibenzyl alcohol after the reaction to an organic phase in a solvent extraction mode, and then purifying the dibenzyl alcohol in the same solvent crystallization mode.
Disclosure of Invention
Based on the problems in the prior art, the invention provides a method for efficiently separating dibenzyl alcohol in a dibenzyl alcohol production process. Selecting a proper solvent, extracting the product dibenzyl alcohol after the reaction is finished into an organic phase by a solvent extraction mode, and then purifying the dibenzyl alcohol by the same solvent crystallization mode.
A method for purifying dibenzyl alcohol comprises the following steps:
the method comprises the following steps: adding an alcohol extracting agent into a solution of dibenzyl alcohol and saline water serving as main components for extraction, standing and layering;
step two: separating liquid at a set temperature, and collecting an oil phase;
step three: and concentrating the collected oil phase, naturally cooling to room temperature, and recrystallizing to obtain white needle-shaped solid, namely the dibenzyl alcohol.
Preferably, the alcohol is a monohydric alcohol.
Preferably, the number of C in the monohydric alcohol is 4-8.
Preferably, the monohydric alcohol is n-butanol, n-hexanol, n-heptanol, n-octanol, or benzyl alcohol.
Preferably, the extraction temperature is less than 93 ℃.
Preferably, the extraction temperature is 75 ℃.
Preferably, the purification method can be repeatedly applied.
Preferably, the purification method can be repeated more than 5 times.
Advantageous effects
1. The invention solves the problems that in the prior art, in the process of water distillation of a crude product after the reaction for producing the dibenzyl alcohol, water with 15 times of mass equivalent of the raw material of the dibenzyl chloride is required to be added for the alkaline hydrolysis reaction to ensure the full hydrolysis of the dibenzyl chloride, 65-75% of water is required to be distilled out after the alkaline hydrolysis reaction is finished, the specific heat of the water is large, the whole process consumes too long time and consumes huge energy, and the top pipeline is blocked due to the fact that the material is taken out by water vapor to be cooled and crystallized at the top frequently; secondly, materials are remained in the brine after water evaporation, the brine cannot be recycled, and the material consumption is large; and thirdly, the two-step crystallization step is complicated and is not beneficial to the technical problem of large-scale production.
2. Through a series of experiments, the invention finds that the n-butyl alcohol is the best extractant for separating the dibenzyl alcohol.
3. The invention finds that the optimum temperature for extracting the dibenzyl alcohol by the n-butyl alcohol is 75 ℃ through a plurality of experiments.
4. The separation method of the invention can be repeatedly applied.
Drawings
FIG. 1 is a reaction scheme of a method for efficiently separating dibenzyl alcohol.
Detailed Description
The technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings, and it is to be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments; all other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without any inventive step, are within the scope of the present invention.
Example one
In order to achieve the purpose of extracting the product of dibenzyl alcohol after the reaction to an organic phase by a solvent extraction mode and then purifying the dibenzyl alcohol by a solvent crystallization mode. The present invention contemplates various common organic solvents.
And (3) after the step of synthesizing the p-phenylbenzyl alcohol (the yield is 37g, and the water amount is 600g), adding 100g of an extracting agent for extraction, separating liquid while the liquid is hot, extracting the water phase once by using 100g of the extracting agent, and collecting an oil layer. And naturally cooling the oil phases collected in the two times to room temperature respectively, recrystallizing to obtain white needle-shaped solids, and calculating the extraction rate. In the embodiment, the quality of the product in the extraction solvent/the total quality of the crude product is determined by adopting an internal standard method; the extraction temperature was 70 ℃. The extraction data of p-phenylbenzyl alcohol in different solvents are obtained, and the results are shown in the table I, the table II and the table III:
Table I table-extraction efficiency of p-phenylbenzyl alcohol in various organic solvents
Table II various organic solvents extraction efficiency table for o-phthalic dibenzyl alcohol
Table three extraction efficiency table of p-m-benzenedibenzyl alcohol in various organic solvents
From the data in table one, table two and table three, it is found that since dibenzyl alcohol has two hydroxyl groups, it has strong hydrophilicity in water, the extraction efficiency of low polar solvents such as alkane and toluene and non-hydrophilic solvents such as ethyl acetate and chloroform is very low, and the alcohol extraction effect has better effect compared with other types of extractants. Meanwhile, in the investigation of the extraction efficiency of the alcohol solvent, the effect of the n-butanol is the best. As the alkyl chain of the alcohol molecule is increased, the hydrophobicity of the alcohol molecule is increased, and the extraction efficiency of the alcohol molecule on the dibenzyl alcohol is reduced in the extraction result. And the ethanol with shorter alkyl chain than the n-butyl alcohol and the propanol are mutually soluble with water, so that the extraction cannot be carried out.
Example two
Based on the best n-butanol extraction effect obtained in the first embodiment, the best n-butanol extraction temperature will be considered in this embodiment. In the temperature investigation, different temperatures also have a significant effect on the extraction efficiency. At normal temperature, the extraction efficiency of the n-butyl alcohol is poor due to the slow molecular motion rate of two phases at low temperature; along with the rise of the temperature, the extraction efficiency of the n-butanol is gradually increased to be optimal when the temperature is 75 ℃; after the temperature is further raised, the extraction and liquid separation effects are reduced due to the azeotropic property of n-butanol and water at 93 ℃. The extraction efficiency of n-butanol to p-phenylbenzyl alcohol at different temperatures is shown in table four:
TABLE IV extraction efficiency table of n-butanol to p-phenylbenzyl alcohol at different temperatures
EXAMPLE III
Based on the best results in example two, after two extractions of the reacted aqueous solution, the oil phase was collected and concentrated for post-treatment. The water phase carries a small amount of dibenzyl alcohol and n-butanol, and the water phase is applied to the next batch of reaction. After the salt content in the water is basically saturated, the water phase is completely evaporated out for continuous use after the salt content is used for 5 times, and the solid salt is subjected to harmless treatment.
1. Adding 30g of sodium carbonate (1.1equiv.) and 600g of water into a three-neck flask, stirring uniformly, then adding 45g of p-dichlorobenzene and 4.5g of n-butanol, heating, refluxing and reacting for 4.5 hours, adding 100g of n-butanol for extraction when the reaction is finished and cooling to about 80 ℃, separating liquid while hot, extracting the water phase once by using 100g of n-butanol, collecting an oil layer, concentrating until the weight of the oil phase is about 80g, naturally cooling the oil phase to room temperature, and recrystallizing to obtain 24.8g of white needle-shaped solid with the yield of 70% (fresh water). The water layer is collected and reused for the next batch.
2. Adding 30g of sodium carbonate (1.1equiv.) into a three-neck flask, using 530g of saline water for the first time, adding 70g of fresh water, stirring uniformly, adding 45g of p-benzyl dichloride (1.0euqiv.), heating and refluxing for reaction for 5 hours without adding n-butyl alcohol, adding 100g of n-butyl alcohol for extraction when the reaction is finished and cooling to about 75 ℃, separating liquid while hot, extracting a water phase once by using 100g of n-butyl alcohol, collecting an oil layer, concentrating until the weight of the oil phase is about 80g, naturally cooling the oil phase to room temperature, and recrystallizing to obtain 27.0g of white needle-shaped solid with the yield of 76% (using the water phase for the first time). The water layer is collected and reused for the next batch.
3. Adding 30g of sodium carbonate (1.1equiv.) into a three-neck flask, adding 520g of brine for the third time and 80g of fresh water, stirring uniformly, adding 45g of p-benzyl dichloride (1.0euqiv.), heating and refluxing for 5 hours without adding n-butyl alcohol, adding 100g of n-butyl alcohol for extraction when the reaction is finished and is cooled to about 75 ℃, separating liquid while hot, extracting an aqueous phase once by using 100g of n-butyl alcohol, collecting an oil layer, concentrating until the weight of the oil phase is about 80g, naturally cooling the oil phase to room temperature, and recrystallizing to obtain 27.7g of white needle-shaped solid with the yield of 78% (the water phase is used for the third time). Collecting water phase, evaporating water, reusing the evaporated water, and performing harmless treatment on salt.
4. Adding 30g of sodium carbonate (1.1equiv.) into a three-neck flask, adding 530g of brine for the first time, adding 70g of fresh water, stirring uniformly, adding 45g of o-benzyl dichloride (1.0euqiv.), heating and refluxing for reaction for 4.5 hours without adding n-butyl alcohol, adding 100g of n-butyl alcohol for extraction when the reaction is finished and cooling to about 75 ℃, separating liquid while hot, extracting an aqueous phase once with 100g of n-butyl alcohol, collecting an oil layer, concentrating until the weight of the oil phase is about 80g, naturally cooling the oil phase to room temperature, and recrystallizing to obtain 24.1g of white solid with the yield of 68% (fresh water). The water layer is collected and reused for the next batch.
5. Adding 30g of sodium carbonate (1.1equiv.) into a three-neck flask, using 530g of saline water for the first time, adding 70g of fresh water, stirring uniformly, adding 45g of o-benzyl dichloride (1.0euqiv.), heating and refluxing for reaction for 5 hours without adding n-butyl alcohol, adding 100g of n-butyl alcohol for extraction when the reaction is finished and cooling to about 75 ℃, separating liquid while hot, extracting an aqueous phase once by using 100g of n-butyl alcohol, collecting an oil layer, concentrating until the weight of the oil phase is about 80g, naturally cooling the oil phase to room temperature, and recrystallizing to obtain 25.9g of white solid with the yield of 73% (using the aqueous phase for the first time). The water layer is collected and reused for the next batch.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (1)
1. A method for purifying dibenzyl alcohol comprises the following steps:
adding 30g of sodium carbonate and 600g of water into a three-neck flask, uniformly stirring, then adding 45g of p-dichlorobenzene and 4.5g of n-butanol, heating, refluxing and reacting for 4.5 hours, cooling to 80 ℃ after the reaction is finished, adding 100g of n-butanol, extracting, separating liquid while hot, extracting the water phase once with 100g of n-butanol, collecting an oil layer, concentrating until the weight of the oil phase is 80g, naturally cooling the oil phase to room temperature, recrystallizing to obtain 24.8g of white needle-shaped solid, and collecting the water layer for next batch.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1623969A (en) * | 2003-12-03 | 2005-06-08 | 上海化学试剂研究所 | Method for preparing 1,4-benzene dimethanol |
| CN102060668A (en) * | 2010-11-29 | 2011-05-18 | 武汉有机实业有限公司 | Method for preparing o-xylene-alpha, alpha'-diol |
| CN102666458A (en) * | 2009-11-23 | 2012-09-12 | 布特马斯先进生物燃料有限责任公司 | Recovery of butanol from a mixture of butanol, water, and an organic extractant |
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| CN105646152B (en) * | 2014-12-04 | 2018-02-09 | 中国石油化工股份有限公司 | A kind of preparation method of phthalyl alcohol |
| CN107324971A (en) * | 2017-06-30 | 2017-11-07 | 长兴化学工业(中国)有限公司 | The method for preparing cyclohexanedimethanol and its pre-reaction material |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1623969A (en) * | 2003-12-03 | 2005-06-08 | 上海化学试剂研究所 | Method for preparing 1,4-benzene dimethanol |
| CN102666458A (en) * | 2009-11-23 | 2012-09-12 | 布特马斯先进生物燃料有限责任公司 | Recovery of butanol from a mixture of butanol, water, and an organic extractant |
| CN102060668A (en) * | 2010-11-29 | 2011-05-18 | 武汉有机实业有限公司 | Method for preparing o-xylene-alpha, alpha'-diol |
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