JPS6191144A - Preparation of neopentyl glycol - Google Patents

Abstract

PURPOSE:To obtain the titled compound and a salt of formic acid efficiently from a reaction product solution, by separating the reaction product liquid obtained by reacting isobutylaldehyde with formaldehyde in the presence of an alkali metal hydroxide into two layers, and treating each layer separately. CONSTITUTION:Isobutylaldehyde 2 is reacted with formaldehyde 3 in the presence of an alkali metal hydroxide 4 in a reactor 1 to give a reaction product solution 5 containing neopentyl glycol (NPG) and a salt of formic acid, which is then neutralized with formic acid 7 in a neutralization chamber 6 to cut a lower-boiling point component 12 such as methanol in a low-boiling fraction cutting column 9. The resultant solution is separated into two layers of the organic phase 15 mainly containing NPG and the aqueous phase 16 mainly containing the salt of formic acid at 20-90 deg.C, preferably 30-65 deg.C, which are separately treated by the well-known method, respectively. Both NPG useful for production of polyester resin, etc., and the salt of formic acid useful as a raw material for hydrosulfite, etc., are obtained economically in high yield and quality.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to isobutyraldehyde (hereinafter referred to as IBA)
Neopentyl glycol (hereinafter referred to as NPC) obtained by reacting and formaldehyde in the presence of an alkali metal hydroxide
) and formate are concentrated,
Alternatively, the present invention relates to a method for producing NPG and formate by separating two layers without concentration and treating each layer separately.

NPC has two highly reactive primary alcoholic hydroxyl groups in symmetrical positions within one molecule, and because it does not have a hydrogen atom in the central carbonate atom, it is not suitable for other diols. Displays many distinctive qualities that are not seen.

It has a wide range of industrial uses, and the polyester resin synthesized using this material as a raw material has very good thermal stability, heat resistance,
It exhibits alkali resistance and weather resistance, and also has excellent electrical properties, making it an extremely useful material for industrial applications such as unsaturated polyester resins, alkyd resins, polycarbonates, polyester isocyanates, and linear polyurethanes. .

On the other hand, formate salts are also industrially useful substances; for example, sodium formate is an indispensable product as a raw material for producing hydrosulfide.

(Prior Art) The following method has been proposed for separating NPG and formate from a reaction product solution containing NPC and formate.

(1) After almost completely evaporating water from the reaction product liquid, add a water-soluble solvent such as ethyl alcohol,
A method in which an aliphatic alcohol such as iso- or normal-propyl alcohol, acetone, dioxane, or ethyl acetate is added, NPC is dissolved in these solvents, and the formate is separated by filtration while hot. (2) Reaction formation Use the liquid as it is or after concentrating it to some extent and use a water-insoluble solvent, such as ketones with 4 to 12 carbon atoms such as methyl isobutyl ketone and methyl ethyl ketone, and ethers with 5 to 10 carbon atoms such as diisopropyl ether and di-normal propyl ether. aromatic hydrocarbons having 6 to 9 carbon atoms, such as benzene, toluene, xylene, pseudocumene, or partially water-soluble alcohols, such as normal and isopropyl alcohol;
There is a method in which NPC is mixed with butyl alcohol, isobutyl alcohol, etc., selectively dissolved in this solvent, and separated into an organic phase and an aqueous phase containing formate.

(Problems to be solved by the invention) However, in method (1), there are problems with equipment and continuity for completely distilling off water, and there are difficulties in handling slurry at the time when formate is precipitated. , Hygiene problems due to heat-temperature filtration, Safety issues such as explosion protection for solvents that often occur when using the r-legal method with the centrifugation method, Relationship between the r-filtration separation process and continuity, Formate Industrial implementation is extremely difficult due to problems such as adhesion loss of the solvent and NPG, as well as loss of some NPG and pollution load due to water distillation.

Method C) is a rational method, but the problem is that its rationality is lost depending on the composition of the extract, the type of extract, etc.

That is, in the conventional method, the reaction product liquid is concentrated as it is or after being concentrated to some extent, and then the entire amount is subjected to solvent extraction by contacting with an extractant.

However, although these methods differ depending on the type of extractant and the type of extraction equipment, for example, when methylene chloride, trichloroethylene, benzene, xylene, etc. are used as the extractant, the formate concentration in the reaction product solution is If the temperature is too high, it becomes a suspended state or a three-layered state and may not be separated into an extract layer and a raffinate layer, making industrial implementation difficult. In addition, ketones having 4 to 12 carbon atoms are said to be relatively easy to perform solvent extraction.

For example, separation problems with methyl ethyl ketone and methyl isobutyl ketone are small, but the solubility of the target substance NPC of the present invention is not very high, so when using these extractants, it is necessary to add an extractant to the extractant. If the size is not large, the extraction efficiency is poor.

This also leads to the fact that when removing oil in the next step, the more extractant is used, the more energy is required for removing oil, resulting in greater economic loss.

(Means for Solving the Problems) The present invention eliminates these drawbacks and produces NPG and formate in a high yield, high quality, and economically.
A reaction product solution containing NPC and formate obtained by reacting A and formaldehyde in the presence of an alkali metal hydroxide is separated into two layers with or without concentrating, and each layer is treated separately. This is a method for producing NPC by separating and recovering NPC and formate, respectively.

The alkali metal hydroxides used in the present invention include sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, barium hydroxide, thallium hydroxide, and the like. Therefore, formate refers to sodium formate, potassium formate, potassium formate, calcium formate, barium formate, thallium formate, and the like.

For example, in the case of sodium hydroxide, 4
It is preferable to set it as 0-5a74#96.

In addition, the raw material formaldehyde may be an aqueous formaldehyde solution (formalin) or paraformaldehyde, but the higher the formaldehyde concentration, the better.45
It is preferable that the weight is at least 55 to 60 weight % fkg6.

The smaller the amount of water coexisting in the reaction system, the higher the purity and yield of the target NPG and formate can be obtained, and the easier the concentration after the reaction, which is more advantageous in terms of energy. For example, when 48% by weight of sodium hydroxide and 45 to 60% by weight aqueous formalin solution are used, two layers can be separated immediately after neutralization/cutting of the low boiling point fraction without concentrating the reaction product liquid.

There is no particular restriction on the methanol content in formalin since it does not significantly affect the reaction, but usually 1 to 5% by weight is used.

The reaction between IBA and formaldehyde is carried out at a temperature of 60°C or less, p
First, perform an aldol condensation reaction with H7-11.5,
Next, a cross-force nilaallo reaction is carried out at 60 to 80°C to obtain a reaction product containing NPC and formate. The reaction product thus obtained is neutralized with formic acid to remove low-boiling components such as methanol, and then separated into two layers. In this case, it is preferable that the amount of formaldehyde remaining in the reaction product solution is small. .

That is, when formaldehyde is left in the reaction product solution and separated into two layers, approximately 85% of the formaldehyde is distributed to the upper layer solution and 1596% to the lower layer solution. It also has a negative effect on salt quality.

Therefore, the amount of formaldehyde remaining in the reaction product solution before two-layer separation is large (but 0.3% by weight, preferably less than that).

This concentration can be maintained by strictly controlling the reaction such as the charging molar ratio, reaction temperature, and alkali concentration in the system.

The two-layer separation method may be either a batch method or a continuous three-step method.
Separate into light liquid and heavy liquid using a stationary decanter, or mechanically using a clarifier type or separation plate type centrifugal sedimentation machine.

The separation temperature is 20-90°C, preferably 30-65°C.

Here, the upper layer liquid (light liquid) is an aquarium phase containing NPC as a main component, and the lower layer liquid (heavy liquid) is an aqueous phase containing formate as a main component.

The separation ratio of the upper layer/lower layer liquid is approximately 1/1, although it varies slightly depending on the degree of concentration of the reaction product liquid and the separation temperature. Further, the distribution ratios of NPG to the upper layer liquid and formate to the lower layer liquid at this time were 96% and 90%, respectively.

The upper layer liquid and lower layer liquid thus obtained are each treated separately to separate and recover NPG and formate.

Although any conventionally known method can be used to recover NPG from the upper layer liquid, a solvent extraction method is efficient when it is carried out continuously.

The extraction solvent is not limited to known ones, but it is sparingly soluble in water and N
The most advantageous are benzene, trichlorethylene, and IBA, which is one of the raw materials for NPC, the object substance of the present invention, because of their high solubility in PC and good extraction efficiency. Furthermore, methyl isobutyl ketone and the like can also be used by increasing the amount of extractant.

In general, the amount of NPG remaining in the raffinate obtained by solvent extraction of the upper layer liquid (hereinafter referred to as secondary raffinate) is kept within the analysis error range, specifically, 0.1% by weight or less. According to the continuous countercurrent contact method, the amount of solvent required for this is 0.3 to 0.7 times the amount (volume) of the upper layer of the reaction product liquid.

Further, the amount of formate contained in the extract at this time is 50 ppm or less as determined by potentiometric titration analysis.

To recover NPC from the extract obtained by solvent extraction of the upper layer liquid, the oil is first removed by a method such as distillation, and then purified by a recrystallization method or distillation method to obtain the product NPC.

On the other hand, if a solvent other than IBA is used as the secondary raffinate obtained by solvent extraction of this upper layer liquid, the solvent is recovered by a distillation method, etc., and the residual liquid is used as the residual liquid from the previous two-layer separation. Mix with the lower layer liquid and process. When IBA is used as a solvent, it can be recycled to the reaction system as it is or mixed with the lower layer liquid obtained during two-layer separation for treatment.

Formate and partially leaked NPG from this lower liquid
For recovery, NPG is brought into contact with raw material IBA for the main reaction, selectively dissolved in this IBA, and then separated into an IBA phase containing NPC (crude IBA liquid) and an aqueous phase containing formate.

This IBA phase can be used as it is as a reaction raw material.

Further, in the aqueous phase, a trace amount of dissolved IBA is recovered by simple distillation or the like, and then the formate is recovered by concentration and crystallization.

The IBA recovered in this way is also used as is as a reaction raw material.

In addition, it is preferable to use a system containing IBA under a nitrogen atmosphere.

The present invention will now be described in more detail with reference to the accompanying drawings. FIG. 1 is an example of a process diagram for implementing the present invention. In particular, when the upper layer liquid of two-layer separation is extracted with a solvent, IBA, which is one of the raw materials for NPG, which is the target substance of the present invention, is used as a solvent.
This is the case when using .

When a solvent other than IBA is used, the procedure is basically the same except that a step of recovering the solvent from the second raffinate is added.

In the drawing, higher concentration formalin is used in route 3 and route 4 is
A higher concentration alkali metal hydroxide aqueous solution is sent to the first extraction column 3, and the lower layer liquid is separated into two layers from the reaction product liquid via route 36.
The extract obtained by countercurrent contact with IBA in step 5 (crude I
BA) are each fed to reaction 11hI to carry out the aldol condensation reaction and the cross Cannitzaro reaction.

Next, this reaction product liquid is supplied to the neutralization tank 6 through path 5, and formic acid is added through path 7 until the pH value of the reaction product liquid is 9.
Neutralize until it reaches 0.

The neutralized liquid is supplied to the low-boiling fraction cut tower 9 through route 8, and low-boiling fractions such as methanol are removed under reduced pressure of about 700,111 HP.
It is cut and discharged out of the system via route 10, heat exchanger 11, and route 12.

The reaction product liquid extracted from the bottom of the low-boiling fraction cut column 9 is supplied to a separator 14 through a route 13, where it is separated into two layers under normal pressure.

The upper layer liquid containing NPG as a main component is supplied to the second extraction column 17 from route 15, where NPG is extracted by countercurrent contact with IBA supplied from routes 25 and 50.

The extract obtained in this way is supplied to the deoiling tower 20 via route 18.

Further, the second raffinate extracted from the bottom of the second extraction column 17 is circulated directly to the reactor 1 via a route 19.

On the other hand, the extract supplied to the deoiling tower 20 distills off the extractant IBA and partially dissolved water in the form of azeotropic distillation, and passes through a route 21, a heat exchanger 22, and a route 23 to a separation tank 24. supply to

The upper layer of IBA is circulated to the second extraction column 17 via route 25 and used again as an extractant.

A portion of the lower water phase is temporarily transferred to the water retention tank 27 via the route 26.
and the second extraction tower 17 via route 28 according to the required amount.
Supply to the middle upper stage of the In addition, the remaining portion is supplied to the middle and lower part 1ζ of the first extraction tower 35 through the route 49.

Crude NPG extracted from the bottom of the deoiling tower 20 is routed through route 29.
It is then supplied to the rectification column 30.

Product NPC is extracted from the top of the rectification column 30 via a route 31, a heat exchanger 32, and a route 33.

A high boiling point fraction is extracted from the bottom of the column through a path 34.

On the other hand, the lower layer liquid mainly composed of formate obtained during the two-layer separation of the reaction product liquid is supplied to the first extraction column 351 from route 16, and the NPC that has leaked into the lower layer liquid during the two-layer separation is supplied to the first extraction column 351. Collect active ingredients such as

In this method, the raw material IBA from route 2 and the IBA in the raffinate of the first extraction column 35 recovered in the evaporator 38 are combined, and this is used as an extractant for solvent extraction to extract active ingredients such as NPC. A method is taken to collect the

This extract (crude IBA) is supplied directly to the reactor 1 as a raw material via a route 36.

Further, the primary residual liquid in the evaporator 38 is supplied via a route 42 to a concentration crystallizer 43 in the formate recovery step.

In the formate concentration crystallization can 43, water is evaporated by concentration and dehydration, and the evaporated water is discharged from the top of the can through a path 44 to the outside of the system.

A saturated or supersaturated aqueous formate solution is extracted from the bottom of the can through a 4° path, and the formate crystallized by a centrifuge 46 is separated and extracted as a wet formate through a path 47. The f-liquid, a concentrated aqueous formate solution, is circulated through the path 48 to the formate concentration crystallization can 43 again.

(Effects of the Invention) According to the present invention, since the reaction product liquid is separated into two layers and NPC and formate are separated in advance, the extraction load required to recover NPC by solvent extraction is greatly reduced. .

In other words, since the ratio of formate to NPG in the upper layer liquid is overwhelmingly small, the extraction efficiency is high, and depending on the type of solvent, the amount of extractant can be as low as 20% compared to the conventional method in which the reaction product liquid is directly extracted. It can be reduced by ~50%.

This not only makes the extraction device more compact, but also saves a lot of energy in the next step, the oil removal step.

This is particularly effective when IBA, which is the same as the raw material, is used as the extraction solvent.

In addition, despite the high solubility of the target substance NPC and high extraction efficiency, the use of solvents that were unusable due to the high formate concentration resulting in a suspended or three-layered state is also possible. It becomes possible.

This means that the range of solvent selection is expanded, and it is possible to select inexpensive and efficient solvents.

(Example) Next, the present invention will be explained in more detail with reference to Examples.

In the examples, % and parts mean % by weight and parts by weight, respectively.

Further, the numbers indicating the devices used in Example 6 are as shown in FIG.

Example 1 55.5% formaldehyde 3 for the first reaction
96.7 parts was heated to 60°C, and while stirring in a N2 stream, 256.5 parts of 99.4% IBA and 4
8.596 sodium hydroxide 992. ．． 505.5 parts were added through separate nozzle ports. At this time, the feed rate was adjusted so that the reaction temperature was 58 to 60° C. and the sodium hydroxide concentration in the reaction solution was 0.06%.

After reacting at the same temperature for 10 minutes after feeding, then I
13 parts of BA was additionally supplied and reacted at a temperature of 70° C. for 7 minutes. After the reaction, it was neutralized using 8096 formic acid. After neutralization, 16 parts of the low boiling point fraction was cut off using a pressure cuff of 00ml AH9 at a temperature of the reaction product liquid of 80°C.

Then, when the temperature was lowered to 60°C and left to stand, two layers were separated. The amounts and compositions of each layer were as shown in Table 1.

Table 1 455.6 parts of the upper layer liquid 1c Add 80 parts of IBA, 45.
Shaking and stirring were performed at ℃.

Then, the mixture was allowed to stand and separated into an extract layer (upper layer) and a raffinate layer (lower layer). Thereafter, 80 parts of IBA was again added to the raffinate layer and the same treatment was carried out to extract NPC.

This extraction with IBA was repeated three times. The amount of NPC and sodium formate dissolved in 55.1 parts of the secondary raffinate thus obtained was 6.996.39.096, respectively.

On the other hand, the total amount of 618.5 parts of the extract obtained from the three IBA extractions was mixed, and 15 parts of water was further added to this and the formic acid still dissolved in the extract was removed. I washed it for cleaning.

Then, the mixture was allowed to stand still, and 626.5 parts of the extract layer and 7 parts of the aqueous layer were separated.

The amount of formic acid dissolved in the extract after washing was 31 ppm. Also, there are 4 NPCs in the 7 parts of the water layer.
．． It was 8%.

The extract was transferred to a distillation flask and IBA was recovered under reduced pressure, followed by vacuum distillation at 145°C and 775mm.
, 356.0 parts of NPC was obtained as a fraction of H9. This was the first product, and the quality is shown in Table 2.

Then, when washing the extract with water after six IBA extractions (582.0 parts of a mixed liquid obtained by mixing the obtained aqueous layer liquid and the lower layer liquid from the two-layer separation of the reaction product liquid), 256 parts of IBA was added. The mixture was shaken and stirred at 45° C. After standing to separate, an extract (crude IBA) was obtained as an upper layer and a raffinate layer was obtained as a lower layer.

The raffinate was transferred to a rotary evaporator flask, and after distilling off trace amounts of dissolved IBA and other low-boiling fractions under reduced pressure, water was distilled off at a temperature of 85°C and a pressure of 20011+1Hf to obtain sodium formate. was crystallized, further transferred to an evaporating dish, water was distilled off on a hot water bath, and then dried in a drier to obtain 248.3 parts of sodium formate.

The quality of this formic acid is shown in Table 3.

On the other hand, the second extract (crude IBA) was used as it was as an IBA source for the 22nd raw material.

The second reaction and post-treatment method is to add the extract (
The procedure was carried out in the same manner as the first time except that crude IBA) was used, and as a result, 370 parts and 250 parts of NPC and sodium formate were obtained, respectively.

Table 2 shows the NPC quality for the first and second times.

The difference in the amount of NPC obtained between the first and second times in Table 2 is due to the hold-up within the circulatory system.

Example 2 Methyl isobutyl ketone (referred to as MIBK) was added to the upper layer obtained by separating the reaction product liquid into two layers in the same manner as in Example 1.
160 parts of the mixture was added, shaken and stirred, and then left to stand to separate the extract layer (upper layer) and raffinate layer.

Thereafter, 160 parts of MIBK was again added to the raffinate layer, and NPC was extracted in the same manner.

This extraction with MIBK was repeated 5 times.

The contents of sodium NPG1 formate and MIBK in the raffinate thus obtained were 2.496.38.1% and 1.1%, respectively.

On the other hand, the total amount of the extract obtained from the five MIBK extractions was mixed, and the extract after washing with water was used to collect MIBK under reduced pressure.
Next, vacuum distillation was performed to obtain 348.0 parts of NPC as a fraction at 145°C/75o+mHr. This was the first product and its quality is shown in Table 4.

Next, the entire amount of the raffinate obtained by MIBK extraction and the aqueous layer obtained when washing the extract with water were mixed and MIBK was removed under reduced pressure.
I did this. The raffinate obtained by removing MIBK and the lower layer obtained by separation into two layers were mixed, and the raffinate and the lower layer obtained by separating the two layers of the reaction product liquid were treated in the same manner as in Example 1.

Tables 5 and 6 show the amount and quality of NP-To-G and sodium formate obtained by repeating the method twice.

Table 5 Table 6 Example 3 NPC and formic acid were used in the same manner as in Example 2 except that benzene was used instead of adding MIBK to the upper layer obtained by separating the reaction product liquid into two layers. Obtained.

The amount obtained and product quality are shown in Tables 7 and 8, respectively.

Please note that these are a mixture of the first and second products.
It's quantity and quality.

Example 4 NPC and sodium formate were obtained in the same manner as in Example 2, except that methylene chloride was used instead of adding MIBK to the upper layer obtained by separating the reaction product liquid into two layers.

The amount obtained and product quality are shown in Tables 7 and 8, respectively.

These are a mixture of the first and second products.
It's quantity and quality.

Example 5 NPC and sodium formate were obtained in the same manner as in Example 2, except that diisopropyl ether was used instead of adding MIBK to the upper layer obtained by separating the reaction product liquid into two layers.

The amount obtained and product quality are shown in Tables 7 and 8.

Please note that these are a mixture of the first and second products.
It's quantity and quality.

Example 6 Continuous production of NPC and sodium formate was carried out for 20 consecutive days according to the process chart shown in FIG.

From the two-layer separator 14 of the reaction product liquid, 1,302 parts/hour of the lower layer liquid having the composition shown in Table 9 is supplied to the middle upper part of the first extraction column 35, and from route 2 IBA 5 with a purity of 99.096 is supplied.
90.7 parts/hour and purity 78 distilled and recovered from evaporator 38
．． A portion of the aqueous layer liquid obtained when the extract obtained in the second extraction tower 17 was further deoiled in the deoiling tower 2 () via route 49 with 12 parts/hour of 5% IBA and the lower layer of the reaction product liquid. NPG leaked into the liquid was extracted.

The extraction column was of a two-section type, with a packed bed in the lower half and a plate bed in the upper half, and the extraction was carried out at a temperature of 35°C.

The composition of the extract (crude IBA) phase 665.0 parts/hour obtained from the plant was as shown in Table 10.

Next, the entire amount of this extract (crude IBA) was transferred through route 36, and 111.5 parts/hour of the second raffinate obtained when the upper layer of the reaction product liquid was similarly extracted with IBA from the two-layer separation (111.5 parts/hour) The composition is shown in Table 11) was directly added to reactor 1 via route 19.
supplied.

For these IBA sources, 54% formalin (formaldehyde 54.2%, methanol 1.3%)9
23.9 parts/hour and 48.25% hydroxide) IJ
Aqueous solution of 705.5 parts/hour was added, temperature was 63℃,
Residence time 1. The aldol condensation reaction and the cross-force nilaallo reaction were carried out simultaneously under conditions of 9 hours without distinguishing between reaction conditions.

2,403.9 parts/hour of the reaction product liquid in Table 9 was neutralized in neutralization tank 6 by adding 11.0 parts/hour of formic acid with a purity of 80% through route 7 to adjust the pH to 9.0.

After neutralization, the low-boiling fraction is supplied to the low-boiling fraction cut 9 through the route 13, and is continuously distilled under conditions of a temperature of 62° C. and a pressure cuff of 00 ffllH at the top of the column to produce a low-boiling fraction that mainly contains methanol and water from the top of the column 38 parts/hour were cut and discharged to the outside of the system via route 12.

Reaction product liquid extracted from the bottom of the low boiling fraction cut tower 9
Send 2576.9 parts/hour to minute gl unit 14, temperature 45℃
Two-layer separation was performed.

The composition of the upper layer obtained by separating the two layers was as shown in Table 12, with an amount of 1074.7 parts/hour. Also, the amount of lower layer liquid is 1502
The composition in parts/hour was as shown in Table 9 above.

Table 10 Table 11 Table 12 The entire amount of the upper layer liquid obtained by separating the reaction product liquid into two layers is supplied to the second extraction tower 17, and the oil is removed from the oil removal tower 20.
4 upper IBA phase 308° 5 parts/hour, purity 99,096 from route 50, IBA 12.7 parts/hour and part of the lower aqueous phase of liquid separation tank 24 in the middle upper stage of second extraction column 17 37
Continuous extraction of NPC was carried out while feeding 3 parts/hour.

At this time, a reciprocating rotary continuous extraction tower was used as the second extraction tower, with a temperature of 35°C and a reciprocating rotation speed of 400C, P, m.
The conditions were set as follows.

The composition of the obtained extracted liquid phase was 1327.5 parts/hour.
The composition of the second raffinate liquid phase (111.5 parts/hour) was as shown in Table 11 above.

The extracted liquid phase obtained in Table 15 is fed to the deoiling tower 20 at a temperature of 65°C.
, continuous distillation under column top conditions with a pressure of 600 + 1111 HP, and a distillate containing IBA and water as main components from the column top 474.1
55.2 parts/hour of crude NPGB were continuously extracted from the bottom of the column.

The fraction from the top of the column is further separated in a liquid separation tank 24, and 308.5 parts/hour of IBA with a purity of 92.596 in the upper layer is added to the second layer.
Part of the lower aqueous phase in the middle and lower part of the extraction tower 17 37
．． 3 parts/hour was supplied to the middle upper stage, and the remaining 127.5 parts/hour was supplied to the first extraction column 35 via route 49.

The crude NPG from the bottom of the deoiling tower 20 is fed to a packed column type rectification tower 30 consisting of 7 theoretical plates, where it is continuously distilled under conditions of a temperature of 145°C and a pressure cuff of 0 mmH. NPG of high purity quality (as shown in Table 14) 845.1 parts/
(Yield based on IBA: 98.1 mol 96).

In addition, a high boiling point fraction of 8.1 parts/hour is extracted from the bottom of the tower.
It was discharged to the outside of the yarn through the path 34.

On the other hand, 1567.7 parts/hour of the raffinate extracted from the bottom of the first extraction column (the composition is shown in Table 15, 1ζ) is supplied to the evaporator 38, where the dissolved and entrained IBA is removed. After distilling and recovering the formate, the water from route 48 or 7 is distilled off to form formic acid in the concentrated crystallization can 43. IJum is crystallized, and then sodium formate is fractionated in the centrifugal valve #46. The P solution was circulated to the formate concentration can 43.

The quality of the obtained formic acid (575.0 parts/hour) was as shown in Table 16. (Yield 97.9mo-
13%/NaOH standard) Table 14 Table 15 Table 16

[Brief explanation of drawings]

The drawing is an example of a process diagram used in the present invention. DESCRIPTION OF SYMBOLS 1... Reactor, 6... Neutralization tank, 9... Low-boiling fraction cut column, 14... Separator, 17... Second extraction column. 20... Oil removal tower, 24... Liquid separation tank, 27... Water retention tank, 3 ()... Rectification tower, 37... First extraction tower,
38... Evaporator, 43... Concentration crystallizer, 46...
Centrifuge machine. 11.22.32.40 Heat exchanger patent applicant Kazuyoshi Nagano, representative of Mitsubishi Gas Chemical Co., Ltd.

Claims (1)

[Claims] The reaction product solution containing neopentyl glycol and formate obtained by reacting isobutyraldehyde and formaldehyde in the presence of an alkali metal hydroxide is separated into two layers, each of which is treated separately, and neopentyl glycol is separated from each layer. A method for producing neopentyl glycol, which is characterized by separating and recovering pentyl glycol and formate.