The method of producing pentaerythritol

 

(57) Abstract:

Usage: in the technology of organic synthesis, namely pentaerythritol used in paint and other industries. The inventive product: pentaerythritol, BF C5H12O4the duration of the crystallization process 70-95 min, biprobuvannyu cycle 480-540 including the Method includes the interaction of acetaldehyde with formaldehyde in the presence of sodium hydroxide, distillation and evaporation of the reaction solution, a two-stage crystallization, filtration, washing and drying of pentaerythritol. Two-stage crystallization is preliminary adiabatic cooling of the evaporated solution under vacuum at a residual pressure of 28-3 kPa within 15-30 minutes before 55-75oC with subsequent dokladnie in the second stage for 40-80 min under atmospheric pressure. table 1.

The invention relates to the technology of polyols neo-structure, in particular pentaerythritol used in paint and other industries.

A known method of producing pentaerythritol by the interaction of formaldehyde with acetaldehyde in the presence of calcium hydroxide. After you have completed the internal alkalinity and binding of calcium ions. The resulting precipitate gypsum is filtered, and the filtrate, containing in its composition pentaerythritol, formic acid, and a number of process impurities, concentrated by evaporation. The evaporated reaction mass is then cooled in the mold. The precipitate pentaerythritol separated from the liquid phase by filtration, washed, optionally recrystallized in hot water and dried [1]

The disadvantage of this method is the complexity of the quality of the discharge from the reaction mass fine plaster, which complicates the subsequent stage of evaporation, crystallization, filtration and washing of pentaerythritol and reduces the quality of the finished product.

The closest set of features to the present invention is a method of producing pentaerythritol, based on the interaction of acetaldehyde with formaldehyde, taken in excess, in the presence of sodium hydroxide. After completion of the chemical interaction of the reaction solution containing in its composition pentaerythritol, sodium formate and a number of process impurities, is treated with formic acid to remove excess alkalinity environment and subjected to rectification order u what about the highlight of it dissolved sodium formate is directed to the crystallization of pentaerythritol.

The crystallization is carried out by cooling the evaporated solution from an initial temperature equal to 95-105oC, to the end that is equal to 20-25oC, molds, operating under atmospheric pressure and provided with stirring and cooling jackets or coils. The resulting suspension pentaerythritol form, the precipitate is washed of impurities of sodium formiate additionally recrystallized in hot water and dried [2]

This method is not associated with the formation and the need for allocation of gypsum, and is characterized by high quality of the finished product.

The disadvantage of this method is low efficiency of the process of crystallization of pentaerythritol. This is because the process of crystallization of pentaerythritol proceeds in the presence of significant quantities of dissolved sodium formate (28-32% ), which leads to increased viscosity of the liquid phase. As a result, the value of the critical degree of supercooling of the evaporated solution required for the onset of crystallization of pentaerythritol, 15-25oC. Crystallization of pentaerythritol with so much critical of the degree of supercooling of the solution is characterized by spontaneity and poor controllability. This is enteritica, which due to high adhesion to form deposits on the inner walls and the heat transfer surfaces of the mold. The result is delayed the cooling process, and shortens the duration Mezhprombank cycle of crystallization equipment.

The proposed method of producing pentaerythritol, including the interaction of acetaldehyde with formaldehyde in the presence of sodium hydroxide, distillation and evaporation of the reaction solution, crystallization by cooling, filtration, washing and drying of the finished product, characterized in that the pre-crystallization is performed under vacuum at a residual pressure of 28-3 kPa within 15-30 min while cooling the solution to 55-75oC, and then for 40-80 min at atmospheric pressure.

The inventive method improves the efficiency of the process of crystallization of pentaerythritol by improving the conditions of formation and crystal growth, and reduce deposition of product on the inner surfaces of the mold.

This is achieved by the process of crystallization of pentaerythritol is carried out in two stages.

In the first stage crystallization is carried out by cooling the Proposed operation of the first stage provides for the conduct of nucleation and early growth with minimal critical degrees of supercooling of the solution. This is achieved by the fact that when creating above the surface of the evaporated source solution vacuum a certain value observed effect of secondary boiling up. Due to the evaporation of the water required for the onset of crystallization degree of supersaturation of the solution is achieved at a much lower degree of its exposure, which does not exceed 3-5oC. due to this, the formation of crystals of pentaerythritol flows in the most favorable high-temperature conditions. The resulting crystals are characterized by the regularity of its structure and less prone to deposits on the inner surfaces of the mold.

The reduction in the duration of the first stage of 15 min is not acceptable as it does not have time to complete the formation of crystals of pentaerythritol. The increase in the duration of more than 30 minutes does not provide any additional benefits to improve the conditions of the formation of crystals, but causes an increase in the dimensions used for crystallization equipment and increase the cost of evacuation.

The decrease in vacuum to a residual pressure of 28 kPa reduce the effectiveness of secondary boiling solution. Uvelicheniya solution and the deterioration of the conditions of formation of crystals of pentaerythritol.

Reducing the solution temperature less than 55oC is associated with the formation of a large number of high-viscosity foam and worsening conditions for crystal formation. The temperature increase over the 75oC leads to a decrease in the boiling solution and reduction of the resulting crystals on the first stage of the process. This in turn worsens the conditions of crystal growth in the second stage of the process.

In the second stage crystallization was carried out by further cooling the suspension for 40-80 min 20-25oC under atmospheric pressure.

The proposed operating mode of the second stage provides further growth obtained in the first stage of the crystals without appreciable formation of new ones.

The second stage of crystallization in less than 40 minutes is not sufficient for growth of existing crystals, but causes the formation of new nuclei of crystals of pentaerythritol, which have a faulty structure, and tend to Deposit on the inner surfaces of the mold.

The increase in the duration of more than 80 min also undesirable because it does not provide additional crystal growth, but due to the increasing their fur Estimated amount of formaldehyde, water and sodium hydroxide are loaded into the reactor with a cooling jacket and a stirrer. The mixture is cooled to 12-17oC and gradually metered into it calculated the amount of acetaldehyde. Due to the chemcial reaction temperature in the reactor rises to 40-45oC. Then the reaction mixture is acidified with formic acid to pH 5.5 to 6.5 and subjected to distillation, for example, in the nozzle column under a pressure of 0.25-0.3 MPa and a temperature of 125-130oC to remove excess formaldehyde. Then, the solution concentrated by evaporation in an evaporation apparatus.

The evaporated solution containing in its composition 25-30% of pentaerythritol, 15-20% of sodium formate, and a number of technological impurities having a density of 1270-1300 kg/m3and the temperature of 95-105oC, direct to two-stage crystallization of pentaerythritol.

At the first stage the solution is served in a vacuum evaporation chamber, which is an insulated vertical vessel with conical bottom. At the top of the camera there is a drop entrainment and fitting for removal of the formed vapor, coupled with condenser and vacuum pump. Under the influence of vacuum at a residual pressure of 28-3 kPa solution boils inoC. due to adiabatic boiling crystal formation takes place in the most favourable conditions, at low degrees of supercooling of the solution, which does not exceed 3-5oC.

Obtained at the first stage, the suspension is fed to the second stage of crystallization, which is in its dokladnie within 40-60 min 20-25oC in the crystallizers operating under atmospheric pressure and is supplied with cooling jackets or coils. Due to the presence in the initial suspension of a sufficiently large number of ready-made embryos crystals with the correct structure in the second stage is further growth without appreciable formation of new crystal nuclei.

After cooling to a final temperature equal to 20-25oC, the suspension is filtered, for example, on a belt or drum filter, the precipitate is washed of impurities of sodium formiate and recrystallized in hot water. The product was filtered, repeatedly washed and dried in the drying drum by means of hot air.

For the detail of the above provide examples of the proposed method in the proposed modes. For comparison here is an example assests the load 12870 kg technical formalin solution, containing 20% formaldehyde, 3000 kg of sodium hydroxide solution containing 20% NaOH, and 5913 kg of demineralised water. The resulting mixture was intensively stirred and cooled to 15oC, then into the reactor for 60 min gradually metered technical acetaldehyde in the number 632,5 kg After completion of the reaction the mixture (22478,5 kg) is acidified to a pH of 6.0 using formic acid (58,1 kg) and subjected to distillation under a pressure of 0.25 MPa and a temperature of 130oC to remove excess formaldehyde.

The solution emerging from the lower part of the distillation columns in the amount 10833 kg and containing 1555 kg of pentaerythritol and 1020 kg of sodium formiate, mixed with a technological solution containing pentaerythritol and sodium formate, and concentrated by evaporation at 105oC to achieve a density equal to 1280 kg/m3. The evaporated solution in a number 6219 kg and containing 1876 kg of pentaerythritol and 1042 kg of sodium formiate, sent for crystallization of pentaerythritol.

Crystallization was carried out by slow cooling of the solution to the 25oC at atmospheric pressure in the crystallizer equipped with cooling jackets and frame agitators. The resulting suspension (6219 kg) filter, precipitate interacitve 1350 kg

The recrystallized pentaerythritol additionally filtered, washed with water (997 kg) and dried with hot air. The finished product in quantities of 1000 kg Packed in bags.

Example 2. Conditions analogous to example 1. The differences consist in the fact that the crystallization of pentaerythritol is carried out in two stages.

In the first stage, the evaporated solution is cooled for 15 min to 75oC under vacuum at a residual pressure of 28 kPa.

In the second stage, the partially cooled suspension is subjected to a final cooling and crystallization of pentaerythritol under atmospheric pressure in the crystallizer equipped with cooling jackets and frame agitators.

Conditions and results of the implementation of the method with other declare the parameters presented in the table.

From the analysis of experimental data shows that the proposed method can significantly intensify the process of crystallization of pentaerythritol, reducing the duration of 1.6-2.1 times. Simultaneously, significantly reduced deposition of pentaerythritol in the form of a crust on the inner surfaces of the mold and increases the duration of a continuous cycle of operation of the mold is tallization equipment, to increase the effective Fund-time, and also to reduce losses and improve the quality of the finished product.

Literature

1. USSR author's certificate N 585149, class C 07 C 31/24, 1974.

2. U.S. patent N 2951095, CL 260-635, 1960.

The method of producing pentaerythritol, including the interaction of acetaldehyde with formaldehyde in the presence of sodium hydroxide, distillation and evaporation of the reaction solution, crystallization by cooling, filtration, washing and drying of the finished product, characterized in that the pre-crystallization is performed under vacuum at a residual pressure of 28 3 kPa for 15 to 30 minutes while cooling the solution to a temperature of 55 to 75oWith and then for 40 - 80 min at atmospheric pressure.

 

Same patents:

The invention relates to the technology of polyols, in particular pentaerythritol used in paint and other industries

The invention relates to organic chemistry, namely to improve the method of producing pentaerythritol (PE), used in the manufacture of explosives, the simultaneous achievement of calcium formate used in the pulp and paper, leather industries, construction and agriculture

FIELD: chemistry.

SUBSTANCE: present invention relates to a method for synthesis of pentaerythritol and dipentaerythritol, involving reaction of acetaldehyde with formaldehyde in the presence of sodium hydroxide, purification of the reaction solution through distillation of excess formaldehyde, evaporation and crystallisation of technical pentaerythritol, washing the residue, recrystallisation of technical pentaerythritol, separation of the residue from the solution and drying commercial-grade pentaerythritol and treatment of the product after drying. After drying the product is treated through separation, thereby extracting the pentaerythritol fractions most contaminated with non-volatile impurities of dipentaerythritol and cyclic formalin, and the extracted fractions are processed by leaching pentaerythritol with demineralised water at 10-80C and ratio of liquid phase to solid phase equal to (5.5-8)/1, and subsequent separation of the formed pentaerythritol solution and dipentaerythritol precipitate and taking the pentaerythritol solution to the technical pentaerythritol recrystallisation step.

EFFECT: method enables to obtain pentaerythritol with low content of dipentaerythritol and cyclic formalin impurities, as well as recycling of dipentaerythritol.

6 cl, 1 tbl, 7 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing pentaerythritol, involving condensation of formaldehyde with acetyldehyde in the presence of sodium hydroxide, rectification and evaporation of the condensed solution, vacuum crystallisation, filtration, washing the obtained technical pentaerythritol, recrystallisation, filtration and drying the pentaerythritol. The formaldehyde is used in form of a mixture of formalin and paraformaldehyde, where the paraformaldehyde constitutes up to 1/5 of the total amount of formaldehyde in the reaction mixture, the components being in the following molar ratio: acetaldehyde 1; formaldehyde 8.4-8.5; sodium hydroxide 1.15-1.20; water 70-72.

EFFECT: method increases efficiency of the process while ensuring high quality of the ready product.

1 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing pentaerythritol which is used in production of lacquer, plastic and explosives. The method involves condensation of formaldehyde with acetaldehyde in the presence of sodium hydroxide, crystallisation, filtration and drying the pentaerythritol. The formaldehyde source used is paraformaldehyde in form of granules, into which water is added at temperature 402C and stirred for 4.5-5.5 minutes. Paraformaldehyde then undergoes preliminary dissolution in an alkaline sodium hydroxide solution, said paraformaldehyde being taken in amount of 30% of the total weight of sodium hydroxide, for 15-16.5 minutes at temperature 40-45C. Further, acetaldehyde cooled to -100.1C and a residual amount of sodium hydroxide are added under cooling conditions, and pulled out for 15 minutes while gradually raising temperature of the condensed solution to 60C. Formic acid is added to the condensed solution until pH 6.5 is achieved.

EFFECT: high effectiveness of the process while ensuring the required quality of the product.

1 tbl, 1 ex

FIELD: chemistry.

SUBSTANCE: method includes the preparation of a reaction mixture by the introduction of n-butyral and water solution of NaOH into the water solution of formaldehyde in the presence of NaOH, the following extraction of the target product from the reaction mixture by extraction with an organic extragent and purification by vacuum-distillation. The reaction mixture is prepared during 1.5 h at a temperature of 30-46C and pH of the mixture of 9-10.5, as the extragent applied are ethers of the general formula R-O-R', where R and R' are the same or different aliphatic linear, branched or cyclic monovalent hydrocarbon radicals with the number of carbon atoms from 1 to 6; extraction is carried out under excessive pressure at a temperature of 10-100C higher than the temperature of the extragent boiling point under atmospheric pressure.

EFFECT: method makes it possible to obtain the target product of high purity with high output by the application of the simple technology.

10 cl, 1 dwg, 2 tbl, 18 ex

FIELD: concentration of pentaerythrite formate mother liquors in the multi-case evaporation plant with vertical heat exchange tubes for production of high-quality lacquers, additives for oils and other products.

SUBSTANCE: proposed method includes concentration of pentaerythrite formate mother liquors at the first stage by evaporation to saturation state by pentaerythrite and crystallization of pentaerythrite from saturated solution; concentration at the first stage is performed at film flow solution; crystallization is carried out at two stages at forced circulation of suspension thus formed. Secondary vapor is divided into two flows after first stage of evaporation: one flow is delivered to the first stage of crystallization and second flow is delivered to the second stage of crystallization. At the second stage of crystallization boiling point of suspension is maintained at temperature of 45-53°C which is below that at the first stage by 7-20°C. Evaporation plant for processing the pentaerythrite formate mother liquors has two stages of evaporators connected in succession in way of flow of vapor and solution and provided with vertical tubes. Second stage of evaporation plant is just crystallizer provided with circulating loop with pump and vapor separator connected with final condenser by means of vapor pipe line. First stage consists of film liquid flow evaporator; second stage is provided with additional crystallizer with circulating loop and pump and additional condenser connected with vapor separator of additional crystallizer; it is also provided with non-condensable gas discharge unit. Last evaporator of the first stage is provided with additional pipe line for discharge of secondary vapor which is communicated with heating chamber of additional crystallizer. Solution volume of additional crystallizer exceeds that of the first one by 1.5- 2.5 times.

EFFECT: improved quality of crystalline products; increased degree of extraction of pentaerythrite from solution; increased rate of processing the solutions.

6 cl, 1 dwg, 1 tbl

FIELD: chemistry.

SUBSTANCE: present invention relates to a method for synthesis of pentaerythritol and dipentaerythritol, involving reaction of acetaldehyde with formaldehyde in the presence of sodium hydroxide, purification of the reaction solution through distillation of excess formaldehyde, evaporation and crystallisation of technical pentaerythritol, washing the residue, recrystallisation of technical pentaerythritol, separation of the residue from the solution and drying commercial-grade pentaerythritol and treatment of the product after drying. After drying the product is treated through separation, thereby extracting the pentaerythritol fractions most contaminated with non-volatile impurities of dipentaerythritol and cyclic formalin, and the extracted fractions are processed by leaching pentaerythritol with demineralised water at 10-80C and ratio of liquid phase to solid phase equal to (5.5-8)/1, and subsequent separation of the formed pentaerythritol solution and dipentaerythritol precipitate and taking the pentaerythritol solution to the technical pentaerythritol recrystallisation step.

EFFECT: method enables to obtain pentaerythritol with low content of dipentaerythritol and cyclic formalin impurities, as well as recycling of dipentaerythritol.

6 cl, 1 tbl, 7 ex

FIELD: chemistry.

SUBSTANCE: present invention relates to a method of processing filtrate wastes from production of pentaerythritol, containing (wt %): 32-37.81 sodium formate, 22-27 pentaerythritol, 10-11 cyclic monoformals, 2-3 dipentaerythritol, as well as pentaerythritol derivative impurities, to obtain technical pentaerythritol and sodium formate. The method involves treatment of the filtrate with an extraction agent, followed by separation and recycling of the obtained liquid and solid phases. Treatment is carried with water in water/filtrate ration equal to (0.5-1.0)/1 and temperature 15-25C, followed by taking the washed off residue to the evaporation and crystallisation step to obtain technical pentaerythritol and the filtrate solution for evaporation and crystallisation to obtain sodium formate.

EFFECT: efficient method of processing waste filtrate from production of pentaerythritol.

2 tbl, 1 ex

FIELD: process engineering.

SUBSTANCE: invention relates to organic synthesis, particularly, to method of processing commercial sodium pentaerythritol and formiate and may be used in chemical industry, paint-and-varnish industry, etc. Method of processing commercial sodium pentaerythritol and formiate mother solution consists in extracting pentaerythritol and liquid phase separation. Mother solution is diluted by water to content of sodium formiate of 30-32%. Then produced solution is heated to at least 60C and mixed at said temperature for at least 4 hours at the rate of 900-1100 rpm. Then, produced suspension is filtered in vacuum filter to precipitate pentaerythritol and separate filtrate containing sodium formiate to extract the latter therefrom.

EFFECT: separate crystallisation of sodium pentaerythritol and formiate.

2 cl, 1 tbl, 1 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing pentaerythritol, involving condensation of formaldehyde with acetyldehyde in the presence of sodium hydroxide, rectification and evaporation of the condensed solution, vacuum crystallisation, filtration, washing the obtained technical pentaerythritol, recrystallisation, filtration and drying the pentaerythritol. The formaldehyde is used in form of a mixture of formalin and paraformaldehyde, where the paraformaldehyde constitutes up to 1/5 of the total amount of formaldehyde in the reaction mixture, the components being in the following molar ratio: acetaldehyde 1; formaldehyde 8.4-8.5; sodium hydroxide 1.15-1.20; water 70-72.

EFFECT: method increases efficiency of the process while ensuring high quality of the ready product.

1 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing pentaerythritol which is used in production of lacquer, plastic and explosives. The method involves condensation of formaldehyde with acetaldehyde in the presence of sodium hydroxide, crystallisation, filtration and drying the pentaerythritol. The formaldehyde source used is paraformaldehyde in form of granules, into which water is added at temperature 402C and stirred for 4.5-5.5 minutes. Paraformaldehyde then undergoes preliminary dissolution in an alkaline sodium hydroxide solution, said paraformaldehyde being taken in amount of 30% of the total weight of sodium hydroxide, for 15-16.5 minutes at temperature 40-45C. Further, acetaldehyde cooled to -100.1C and a residual amount of sodium hydroxide are added under cooling conditions, and pulled out for 15 minutes while gradually raising temperature of the condensed solution to 60C. Formic acid is added to the condensed solution until pH 6.5 is achieved.

EFFECT: high effectiveness of the process while ensuring the required quality of the product.

1 tbl, 1 ex

FIELD: chemistry.

SUBSTANCE: present invention relates to a method of purifying raw polymethylol, which contains polymethylol of formula (I), as well as a hydroxy acid of formula (IV). According to the present method, raw polymethylol is obtained in a multistep process, wherein at step (a) alkanals react via aldol condensation with formaldehyde in the presence of tertiary amines as catalyst to form methylol alkanals of formula (II). Further, at step (b), the reaction mixture obtained at step (a) is divided by distillation into a still residue primarily containing compounds of formula (II) and a head stream containing low-boiling components. The stream coming from the bottom from step (b) is hydrogenated at step (c). The stream coming from step (c) is then distilled at step (d). Low-boiling components from the stream coming from step (c) are separated, and purification is carried out in a distillation column, wherein the bottom of the distillation column is connected to at least one evaporator with a short dwell time. In formulae , , R in each separate case independently denotes a methylol group or an alkyl group with 1-22 carbon atoms or an aryl group or an arylalkyl group with 6-22 carbon atoms.

EFFECT: method reduces losses in output of polymethylol.

12 cl, 5 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a method of distilling an aqueous polymethylol mixture containing a polymethylol of formula

,

a tertiary amine, water, as well as an adduct of a tertiary amine and formic acid (amine formate). According to the disclosed method, distillation is carried out in a distillation column equipped with a condenser, the lower part of the column being connected to an evaporator, wherein temperature in the lower part of the column is higher than the evaporation temperature of the monoether of formic acid and polymethylol (polymethylol formate) formed during the distillation process. In formula (I), R in each case independently denotes another methylol group or an alkyl group with 1-22 carbon atoms or an aryl or aralkyl group with 6-22 carbon atoms.

EFFECT: method enables to obtain polymethylols with low content of polymethylol formate.

14 cl, 4 ex

FIELD: chemistry.

SUBSTANCE: water solution of sodium salt: nitrate, or halogenide, or their mixture, with the concentration from 10 wt % to the concentration below the saturation line, and with the temperature, which ensures obtaining a mixture with the temperature of 20-40C, when it is mixed with the heated mother liquor, is introduced into the hot mother liquor, which has the technological temperature of 90-100C; the mixture is exposed with mixing for 20-60 minutes, with the following separation of the precipitated sediment of solid pentaerythrite from the liquid salt solution. The said mother liquor and water solution of the said sodium salts are taken in a weight ratio in such a way that the concentration of sodium formiate in the mother liquor after mixing constitutes 15-30 wt %.

EFFECT: method efficiency is achieved due to the reduction of the process time and increased degree of solid pentaerythrite extraction, with the simultaneous creation of the wasteless technology with obtaining two target products.

3 cl, 4 ex

FIELD: technological processes.

SUBSTANCE: invention relates to organic synthesis, particularly to processing of pentaerythritol-formiate mother solutions, and can be used for producing sodium formiate. Method of extracting sodium formiate from pentaerythritol-formiate mother solution involves a step of extracting sodium formiate from mother solution, obtained during production of pentaerythritol, with separation of liquid phase. Separated liquid phase in form of solution containing pentaerythritol with impurities and sodium formiate on the edge of saturation at temperature of 955 C is fed into vessel, mother solution, obtained during production of pentaerythritol, is added at temperature of 455 C, mixture temperature is brought to 55-65 C, mixture is held at this temperature until formation of crystals of pentaerythritol with size of not less than 150 mcm. Obtained suspension is filtered to separate released crystals of pentaerythritol and impurities. Remaining solution of sodium formiate is returned to the step of sodium formiate extracting from mother solution, obtained during production of pentaerythritol.

EFFECT: invention allows to increase efficiency of the process by increasing the amount of sodium formiate, obtained at processing of pentaerythritol-formiate mother solution.

1 cl, 3 tbl, 3 ex

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