KR19980028461A - How to prepare neopentyl glycol - Google Patents

Abstract

The present invention comprises the steps of: 1) obtaining an aldol condensation reaction product containing hydroxyfibaldehyde (HPA) using a tertiary alkyl amine as a catalyst from an aqueous solution of formaldehyde having isobutyl aldehyde and methanol content of 0.1 to 15% by weight; 2) extracting the HPA using octanol from the aldol condensation reaction product, and then distilling and removing the low boiling point material containing triethylamine and isobutylaldehyde from the extracted HPA; 3) Hydrogenation of the separated HPA in a gas-liquid reactor under a nickel catalyst to produce crude neopentylglycol (NPG), at which time a portion of the crude NPG product is circulated with a pump and sprayed through a nozzle at the reactor inlet to hydrogenate Reusing as a reactant; And 4) extracting the crude neopentyl glycol using water and then distilling to purify the neopentyl glycol. The method of the present invention can easily prepare high purity NPG.

Description

How to prepare neopentyl glycol

The present invention relates to a method for continuously preparing neopentyl glycol (2,2-dimethyl-1,3-dihydroxypropane, hereinafter abbreviated as NPG). Specifically, the present invention performs condensation reaction using isobutyl aldehyde and formaldehyde as a catalyst as a tertiary amine, such as trialkylamine, to obtain hydroxyfibaldehyde (hereinafter abbreviated as HPA), followed by nickel catalyst. The present invention relates to a method for producing NPG by carrying out a hydrogenation reaction in a slurry phase.

NPG is a white crystalline substance having a melting point of 130 ° C. to 131 ° C., and is widely used in the industry as a raw material for powder coatings of various plastics such as alkyd resins, synthetic lubricants, plasticizers, and fiber processing agents. Therefore, research efforts to produce NPG in an economical manner as one of the industrially important intermediates have been continuously performed.

NPG is produced by hydrogenating the crude HPA produced by the aldol condensation of isobutyl aldehyde and formaldehyde, as shown in Scheme 1 below:

In the aldol condensation reaction of isobutyl aldehyde and formaldehyde, alkali metal compounds such as alkali hydroxides and alkali carbonates have conventionally been used as catalysts. However, when using a catalyst such as sodium carbonate, large amounts of organic acid salts are produced, which are problematic in the separation and treatment as reaction byproducts.

US Pat. No. 3,808,280 used tertiary amines as useful catalysts in aldol condensation reactions. Aldol condensation reactions with tertiary amines increase the yield of HPA, but tertiary amine salts formed by the reaction of these tertiary amines with organic acids in the reaction mixture deactivate hydrogenation catalysts such as Raney nickel and decompose HPA at high temperatures. Reaction causes a direct decrease in NPG yield and catalyst poisoning.

In the aldol condensation reaction, isobutyl aldonic acid, NPG-isobutylate, etc. are produced as main by-products, and they are isobutanol or trimethylpentanediol (2,2,4-trimethyl-1,3-pentanediol) by hydrogenation. , Hereinafter abbreviated as TMPD). They have similar boiling points as NPG and are very difficult to separate by distillation.

In US Pat. No. 4,885,515, hydrogenation was carried out using a copper chromite catalyst containing manganese directly without separating triethylamine catalyst from the aldol condensation reaction. However, these hydrogenated catalytic reactors have disadvantages in commercialization such as high equipment costs and catalyst replacement due to deactivation of the catalyst by using high temperature and high pressure.

In US Pat. No. 4,851,592, this hydrogenation reaction was carried out using a gas sparger reactor as a slurry reaction using Raney nickel. However, the crude HPA was directly introduced into the hydrogenation reactor to perform the hydrogenation reaction, and the catalyst poisoning caused by the organic acid salt of the tertiary amine contained in the reaction product or the unreacted material was severe, and thus, there was a problem in operating for a long time.

Therefore, in order to suppress the formation of side reactants and to obtain high yields, organic acid salts, residual aldol condensation catalysts, and unreacted substances, which cause catalyst poisoning, must be removed at the first stage of the hydrogenation reaction. In addition, a process of maximizing NPG yield and minimizing side reactions is desirable.

In addition, in the conventional aldol condensation reaction, in the case of formaldehyde, which is a reactant, methanol is discharged together with the waste water after the reaction by using an aqueous solution containing 8-15% of methanol, and a separate methanol separation distillation step is required to control this. . Therefore, there is a disadvantage in that the process is complicated and the apparatus cost is excessive.

Efficient purification is necessary to obtain purified NPG from crude NPG by hydrogenation. The crude NPG, which is a hydrogenation reactant, includes TMPD, hydroxypivalic acid NPG ester (hereinafter abbreviated as HPNE), and the like.

HPNE is formed by the Tishchenko reaction of the aldol condensation reaction product HPA and is not removed in the hydrogenation reaction, and can be converted to NPG by saponification with sodium hydroxide.

HPNE and TMPD have a boiling point very similar to that of NPG, which cannot be separated by simple distillation, and because HPNE is unstable when distilling the reaction mixture and leads to a decrease in yield of NPG, it is commercially saponified by the addition of sodium hydroxide. The reaction is converted to NPG. However, sodium salts of HPA or other organic acids produced by the saponification reaction promote the decomposition reaction of NPG at a high temperature of 140 ° C. or higher, thereby limiting the distillation process. In addition, it is impossible to remove TMPD that does not convert to a nonvolatile sodium salt during saponification.

Various methods have been proposed as a method for purifying NPG from crude NPG. For example, a method of extraction using a solvent, vacuum distillation, crystallization, and the like have been proposed. However, these methods are inadequate for commercialization.

US Patent No. 2,895,996 proposes a method for obtaining high purity NPG by steam sublimation of crude NPG through saponification. Here, the distillation temperature was limited to 70 ° C. to 140 ° C. in order to prevent the decomposition of NPG by sodium salt, which was uneconomical due to the low temperature at the top of the sublimation device.

US Patent No. 4,935,555 proposes a method of distilling NPG using a thin film vacuum distillation apparatus. However, in commercializing this, it is uneconomical due to excessive equipment cost and the like, the recovery rate of NPG to sub-reactants and distillation residues is reduced, and TMPD, which is not converted into salts during saponification reaction, is impossible to separate and lowers purity.

Therefore, it is an object of the present invention to continuously manufacture NPG in a simple and economical way with high yield and high purity.

1 is a schematic view showing a pipe for continuously producing neopentyl glycol of the present invention.

* Explanation of symbols for the main parts of the drawings

1-3, 5, 7, 8, 9, 11, 14, 16, 17, 19, 21, 23, 24, 25, 27, 28, 29, 31, 32, 34, 35,

37, 38, 39: piping

4: aldol condensation reactor 12, 15, 26, 33: distillation column

6, 10, 30: extraction politics 18: hydrogenation reactor

20: saponification reactor 22: extraction device

36: Flickr

In order to achieve the above object, in the present invention, 1) hydroxyfibaldehyde (HPA) -containing aldol condensation is obtained by using a tertiary alkyl amine as a catalyst from an aqueous solution of formaldehyde having isobutyl aldehyde and methanol content of 0.1 to 15% by weight. Obtaining a reaction product; 2) extracting the HPA using octanol from the aldol condensation reaction product, and then distilling and removing the low boiling point material containing triethylamine and isobutylaldehyde from the extracted HPA; 3) Hydrogenation of the separated HPA in a gas-liquid reactor under a nickel catalyst to produce crude neopentylglycol (NPG), at which time a portion of the crude NPG product is circulated with a pump and sprayed through a nozzle at the reactor inlet to hydrogenate Reusing as a reactant; And 4) extracting the crude neopentylglycol using water and then distilling to purify neopentylglycol.

Hereinafter, the present invention will be described in detail.

First, hydroxyfibaldehyde (HPA) is prepared by an aldol condensation reaction of isobutylaldehyde and an aqueous formaldehyde solution having a methanol content of 0.1 to 15% by weight in the presence of a tertiary alkyl, for example, triethylamine catalyst. As for an aldol condensation reaction temperature, 70 to 90 degreeC is suitable, and the residence time of a reaction material is suitable for about 1 to 3 hours.

Octanol is mixed with the HPA-containing aldol condensation reaction product obtained above, HPA is extracted into the organic layer, and isobutyl aldehyde, triethylamine, water, etc., which are low boiling point substances, are distilled off from the extracted HPA. As a result, the triethylamine salt and formaldehyde which cause catalyst poisoning can be removed, so that the hydrogenation reaction of HPA can be stably operated continuously.

The octanol used is suitably 0.3 to 4 times by weight of the HPA. In addition to the octanol, extraction by adding 1 to 2 times the amount of water in the aldol condensation reaction with respect to the HPA weight can effectively remove the organic acid, the organic acid of triethylamine, and the like which are water-soluble side reactions. At this time, HPA contained in the water layer during the extraction by adding water can be extracted by adding 0.3-1.5 times i-BAL to the water layer and recovered by the aldol condensation reactor.

The separated HPA is hydrogenated in a gas-liquid reactor under a nickel catalyst to prepare crude neopentyl glycol. The hydrogenation reaction is carried out at a hydrogen pressure of 100 to 1500 psig and a reaction temperature of 120 ° C to 180 ° C. As Raney nickel catalyst, it has a composition of 85% Ni, 12% Al, 1-4% Mo, 0.8% Fe, and 2 to 10% by weight based on the weight of HPA. Hydrogenation also uses a circulating slurry reactor to reuse part of the product as reactant. Part of the product that is recycled to the reactants is recycled through the pump at high speed and a nozzle is installed in the upper part of the reactor where the reactants are introduced to increase the efficiency of contact of the gaseous hydrogen with the reactant in the liquid state. Can be.

The crude NPG produced after the hydrogenation reaction is saponified to recover NPNE contained in the crude NPG by reacting with alkali such as NaOH.

NPG was extracted into the water layer by supplying 0.5 to 4 times, preferably 1 to 1.5 times, water to the saponification NPG, followed by azeotropic evaporation of water and NPG to remove organic acid salts, which are high boiling point, and then distilled again. Get the product. The obtained NPG product can also be made into a flake product using a flaker.

NPG is recovered by distilling NPG and extracting it by adding octanol to the remaining high boiling point material, and the water layer is treated with wastewater. The methanol content of the formaldehyde aqueous solution, which is a raw material of the aldol condensation reaction, is 0.1 to 15% by weight, preferably 0.1 to 5% by weight, so that the amount of methanol contained in the water discharged to the wastewater is minimized, so that a separate methanol distillation process is performed. No need to be economical.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 is a schematic view showing a pipe for continuously producing neopentyl glycol of the present invention.

Formaldehyde aqueous solution was continuously introduced through the pipe (2), and 1.0 to 1.3 mol of isobutyl aldehyde and 0.03 to 0.06 mol of tertiary alkyl amine, such as triethylamine, were respectively added to 1 mol of the formaldehyde aqueous solution. HPA is synthesized by feeding continuously to the aldol condensation reactor (4) through) and (3).

A part of the aldol condensation reaction product is continuously supplied to the extraction policing tank 6 through the pipe 5 and mixed with octanol supplied through the pipe 38 to extract HPA, and the HPA extracted to the organic layer is (9) is supplied to the distillation column (12), and in the distillation column (12), excess isobutyl aldehyde, triethylamine and water having a low boiling point in the aldol condensation reaction product are distilled off through the pipe (13).

As for the temperature of the extraction policing tank 6, 40 degreeC-70 degreeC is suitable. In addition, water may be added to the extraction policing tank 6 in order to effectively remove organic acids, triethylamine, and organic acid salts, which are water-soluble side reactions. The water layer separated from the extraction politics tank 6 is supplied to the mixed politics tank 10 through the pipe 8. In order to recover HPA from organic acids, triethylamine salts, esters and HPA contained in the water layer, isobutyl aldehyde is supplied to the extraction policing tank 10 through the pipe 7 and continuously extracted, followed by aldol through the pipe 39. Recovered to condensation reactor 4 and reused.

HPA, the bottom material of the distillation column 12, is continuously supplied to the hydrogenation reactor 18 through a pipe 14, in which the hydrogenation reaction is carried out in a slurry phase using a Raney nickel catalyst by adding hydrogen. do. The hydrogenation reaction is preferably carried out at a pressure of 100 psig to 1500 psig and a reaction temperature of 120 to 180 ° C.

After the hydrogenation reaction, the crude NPG produced in the hydrogenation reactor 18 is supplied to the saponification reactor 20 through a pipe 19 to recover HPNE contained in the crude NPG as NPG.

NPG obtained through the saponification reactor 20 is supplied to the extraction device 22 through the pipe 21, the amount of water supplied to the extraction device 22 through the pipe 23 is 0.5 to 4 times the amount of NPG Preferably, it is 1 to 1.5 times, and the temperature of the extraction apparatus 22 is 10 to 50 degreeC.

The NPG-containing water layer extracted by the extraction device 22 is continuously supplied to the distillation column 26 through the pipe 25, and in the distillation column 26, azeotropic evaporation of water and NPG from the column top is received into the pipe 27. A mixed policing tank 30 is used to remove organic acid salts, which are high boiling point substances, accumulated at the bottom of the distillation column 26 and recover NPG. In the mixed policing tank 30, NPG is extracted using octanol supplied through the pipe 29, and then recovered by the extraction device 22 through the pipe 32, and the water layer is treated with wastewater through the pipe 31. do. As a result, an organic acid salt, which is a high boiling point material, accumulated at the bottom of the distillation column 26 may not be used as an expensive device such as a thin film distillation device, thereby providing an economic process.

Water and NPG supplied from the distillation column 26 are distilled from the distillation column 33, and the water condensed in the column top is reused in the extraction unit 22 through the pipe 34, and the NPG of the column bottom is piped through the pipe 35. Get At this time, in order to obtain NPG on the flakes, NPG obtained through the pipe 35 is supplied to the flaker 36 to obtain a flake product.

As described above, the hydrogenation reactant is extracted using octanol to selectively remove a small amount of side reactants, and economically produce high purity NPG by a simple distillation purification process, and distillation of the tower top distilled from the distillation column 33. By using water again in the extraction device 22, the amount of waste water can be reduced. In addition, after the aldol condensation reaction to recover the isobutyl aldehyde is a low volatile raw material in the reaction product to recover through the pipe 16 by the extraction distillation in the extraction distillation column 15 to maximize the reaction yield.

Hereinafter, the present invention will be described in detail with reference to Examples.

The present invention is not limited to the contents described in the Examples, and has various scopes of application per unit process, and may be used to prepare compounds having similar properties as NPG as well as NPG by omitting, adding, or different combinations of specific unit processes. Can be.

Example

1) Preparation of Joe HPA

206.8 aldol condensation reactor with a stirrer was continuously fed with 46.8 g / min of isobutyl aldehyde, 42.2 g / min of 37% aqueous formaldehyde solution, and 2.6 g / min of triethylamine, respectively. In order to supply the amount of heat required for the reaction, an electric heater was attached to the outer wall of the reactor to keep the temperature inside the reactor constant at 70 ° C to 90 ° C. Nitrogen was pressurized to maintain 10 to 40 psig to maintain the reaction in the reactor in the liquid phase. The reactor residence time was fixed at 0.5 hour to 2 hours, and crude HPA, the reaction product, was taken out continuously at a rate of 91.6 g / min.

After continuous extraction of the crude HPA, HPA was extracted by adding octanol to remove poisoning substances of the hydrogenation catalyst such as organic acid salt of triethylamine and residual unreacted substances contained therein.

Extraction by octanol was allowed to stand after adding an aldol condensation product including crude HPA and 0.3 to 1 times octanol thereto to a 20 L reactor equipped with a stirring apparatus and a jacket, followed by stirring for 30 minutes to 1 hour. The jacket of the reactor circulated the warm water to maintain the temperature inside the reactor at 30 to 70 ℃. After standing, the layers were separated and HPA extracted in the upper octanol was continuously distilled in an Oldshaw distillation column made of glass having a diameter of 50 mm to remove isobutyl aldehyde and triethyl amine, which are low boiling point materials. The recovered low boiling point material contained water, methanol, and the like in aqueous formaldehyde solution, which was sent to an extraction distillation column to recover isobutylaldehyde and triethylamine and reused as an aldol condensation reaction product.

The number of stages of the distillation column for the low boiling point distillation is 5 to 20 stages, the temperature of the column bottom is 80 ℃ to 110 ℃, the pressure was distilled under 400 to 700 mbar.

The composition of the crude HPA produced by the aldol condensation reaction, the composition after low boiling point distillation and the composition after octanol extraction are shown in Table 1, respectively.

It is noteworthy that the extraction of HPA using octanol significantly removes triethylamine and organic acid salts, which are the main sources of catalyst poisoning, in the hydrogenation of aldol condensation reaction products.

division Aldol condensation product composition Composition after Octanol Extraction Low boiling distillation HPA composition Methanol 0.56 0.39 - Isobutanol - - - water 29.85 12.70 5.88 Octanol - 27.21 30.68 Isobutyl aldehyde 4.87 4.27 0.98 Triethylamine and organic acid salt 3.68 2.62 0.54 Hydroxyfive aldehyde 55.79 48.29 56.33 Neopentyl glycol 0.93 0.76 0.92 Neopentyl glycol ester 3.68 3.44 4.22 Etc 0.64 0.32 0.45

Unit: weight% (quantitative by gas chromatography analysis)

2) Preparation of crude NPG

After low boiling point distillation obtained in 1), crude HPA was hydrogenated in a 2 L autoclave equipped with a stirrer.

The crude HPA was continuously fed to the hydrogenation reactor at 12-15 g / min, and the hydrogenation product was continuously taken out through a filter installed inside the reactor.

The Raney nickel catalyst was used as a catalyst for the hydrogenation reaction, and 6% was used as the HPA standard. The reactor temperature was fixed at 150 ° C. and hydrogen pressure was maintained at 1000 psi. The reaction proceeded for 26 hours continuously and showed no catalyst deactivation.

Table 2 shows the composition change before and after the hydrogenation reaction.

ingredient Pre-reaction composition Post-reaction composition Methanol 0.25 0.37 Isobutanol 0.06 2.02 water 6.31 6.23 Octanol 35.17 34.72 Isobutyl aldehyde 2.29 0.35 Triethyl amine 1.11 1.10 Hydroxyfive aldehyde 48.45 - Neopentyl glycol 3.95 52.96 Neopentylglycol estertrimethylpentanediol 1.540.74 1.520.73 Etc 0.13 -

Unit: weight% (quantitative by gas chromatography analysis)

3) Crude NPG Purification

After the extraction of the octanol obtained in Example 1 in the hydrogenation reactor Raney Nickel The hydrogenation reaction product containing the crude NPG obtained in the above 2) is a continuous extraction apparatus made of a glass of 3m in height 3 inches in diameter, 54 stages Extracted into aqueous solution using.

The extraction tower used for the extraction of the hydrogenation product uses a SCHEIBEL type continuous extraction device having a stirrer installed at the top of the tower so that water and hydrogenation reactants flowing in countercurrent flow smoothly between stages. Was used. Water as an extractant was continuously supplied to the top of the extraction tower by using a pump, and the hydrogenation product was continuously fed to the bottom of the extraction tower by using a metering pump. The ratio of the water and the hydrogenated reactant as the extractant was fixed at 0.8 (weight ratio). NPG is extracted from the water layer as an extractant and discharged to the bottom of the column, and octanol, which is a weight balance, is continuously discharged to the top of the column.

Table 3 shows the extraction test results.

division Flow rate (g / min) weight % NPG Octanol H ₂ O Low boiling point material TMPD HPNE water 175 - - 100.0 - - - Hydrogenation Product 215 48.8 40.9 6.78 - 0.42 3.1 Balance 93.04 1.17 86.98 9.03 - 0.42 2.4 Extract 293.8 31.88 3.63 63.19 - 0.1 1.2

Extraction tower temperature = 30 ℃

Dwell time = 25 minutes

Extraction efficiency = 99.19%

4) Recovery of NPG from HPNE

Since HPNE contained in the hydrogenation product obtained in 2) is difficult to be separated from NPG by distillation, NPG was extracted in the same manner as 2) after decomposing HPNE by adding NaOH to convert NPNE and sodium salt. The experimental results are shown in Table 4 below.

division Flow rate (g / min) weight % NPG Octanol H ₂ O Low boiling point material TMPD HPNE Sodium salt water 175 - - 100.0 - - - - Hydrogenation products 215 47.7 38.7 10.8 - 0.4 0.1 2.3 Balance 88.9 0.38 89.92 8.9 - 0.6 0.2 - Extract 298.8 30.71 2.35 66.04 - 0.1 - 0.8

Extraction tower temperature = 32 ℃

Dwell time = 30 minutes

Extraction efficiency = 99.43%

In the above results, the extraction column which extracts NPG from the hydrogenation product using water can be operated at room temperature, and the water must be sufficiently mixed in the extraction column with the extractant water and the crude NPG content of the hydrogenation reaction product. In addition, it can be seen that the boiling point, such as TMPD and HPNE, which are side reactions of the aldol condensate, was difficult to separate by distillation, so that most of the substances were extracted into the octanol layer.

5) Recovery of NPG from Sodium Salt

In order to remove sodium salt accumulated in the column by azeotropically distilling NPG and water from the distillation column, the extract obtained in 4) was added with water and octanol to the column bottom containing sodium salt in a mixed politics tank equipped with a stirrer and a stationary tank. NPG was extracted into the organic phase in a ratio of: 0.6: 2. Sodium salt was mostly removed by the water layer, and NPG extracted into the organic phase was sent to the extraction tower to recover the NPG. The extraction experiment results are shown in Table 5.

ingredient Columnar composition Organic phase composition Water layer composition Neopentylglycol sodium salt and other octanol water 7030-- 22.510.5871.855.06 9.3934.270.9455.4

Unit: weight% (quantification by gas chromatography analysis)

Extraction temperature: 75 ℃

NPG recovery: 88.8%

Sodium salt removal rate: 95.9%

As described above, according to the production method of the present invention, high-purity neopentyl glycol can be continuously and economically produced.

Claims (7)

1) obtaining an aldol condensation reaction product containing hydroxyfibaldehyde (HPA) using a tertiary alkyl amine as a catalyst from an aqueous solution of formaldehyde having isobutyl aldehyde and methanol content of 0.1 to 15% by weight; 2) extracting the HPA using octanol from the aldol condensation reaction product, and then distilling and removing the low boiling point material containing triethylamine and isobutylaldehyde from the extracted HPA; 3) Hydrogenation of the separated HPA in a gas-liquid reactor under a nickel catalyst to produce crude neopentylglycol (NPG), at which time a portion of the crude NPG product is circulated with a pump and sprayed through a nozzle at the reactor inlet to hydrogenate Reusing as a reactant; And 4) A method for producing neopentyl glycol comprising extracting the crude neopentyl glycol using water and then distilling to purify. The method of claim 1, Methanol content in the step 1) characterized in that 0.1 to 5% by weight. The method of claim 1, Octanol in the step 2) characterized in that used 0.3 to 4 times by weight of the HPA. The method of claim 1, Extracting by adding 1 to 2 times the water relative to the weight of HPA with octanol in the step 2). The method of claim 1, Hydrogenation in step 3) is characterized in that carried out at a pressure of 100 psig to 1500 psig and a temperature of 120 to 180 ℃. The method of claim 1, In step 4), characterized in that using 0.5 to 4 times the water relative to the crude NPG. The method of claim 1, And distilling the crude NPG in step 4) to recover the NPG by adding octanol to the remaining high boiling point material.