JP2021038189A - 1,3-butylene glycol product - Google Patents

Abstract

To provide a high-purity 1,3-butylene glycol product which is colorless and odorless, and hardly causes coloring over time.SOLUTION: In the 1,3-butylene glycol product, the area ratio of a peak appearing in the relative retention time range from 2.3 to 2.4 is 1000 ppm or less if the relative retention time of the peak of 1,3-butylene glycol is taken as 1.0 in a gas chromatography analysis under specific conditions.SELECTED DRAWING: Figure 1

Description

The present invention relates to 1,3-butylene glycol products.

1,3-butylene glycol is a colorless, transparent, odorless liquid, has properties such as low volatility, low toxicity, and high hygroscopicity, and is excellent in chemical stability. For this reason, 1,3-butylene glycol has a wide range of uses, including raw materials for various synthetic resins and surfactants, as well as cosmetics, hygroscopic agents, high boiling point solvents, and antifreeze materials. Particularly in recent years, attention has been paid to 1,3-butylene glycol having excellent properties as a moisturizer, and the demand in the cosmetics industry is expanding.

The 1,3-butylene glycol obtained by the conventional production method may have an odor due to the influence of by-products. Further, even if it is transparent immediately after production, it may be colored with time, which has been a problem when it is stored for a long period of time.

For example, when using cosmetics or when storing them after use, the cosmetics are exposed to the air. In addition, when manufacturing cosmetics, the work is generally performed in an air atmosphere, and the cosmetics may be heated for the purpose of sterilization or the like. When 1,3-butylene glycol obtained by a conventional method is used in cosmetics, coloring may proceed due to the presence of air or the influence of heating. In order to solve such a problem, it has been required to remove by-products from the crude 1,3-butylene glycol to purify the 1,3-butylene glycol.

As a method for obtaining 1,3-butylene glycol having high purity, a method of adding caustic soda to crude 1,3-butylene glycol obtained by hydrogen reduction of acetaldehydes and performing distillation has been proposed. Further, after adding an alkali metal base to crude 1,3-butylene glycol excluding high boiling point and heat-treating, 1,3-butylene glycol was distilled off to separate the alkali metal compound and high boiling point residue as a residue. Subsequently, a method of distilling a low boiling point substance from the 1,3-butylene glycol distillate has been proposed (Patent Documents 1 to 6). As described above, various methods for purifying 1,3-butylene glycol have been proposed in order to obtain highly pure 1,3-butylene glycol.

Japanese Unexamined Patent Publication No. 7-258129 International Publication No. 00/07969 Japanese Unexamined Patent Publication No. 2001-213822 Japanese Unexamined Patent Publication No. 2001-213824 Japanese Unexamined Patent Publication No. 2001-213825 Japanese Unexamined Patent Publication No. 2001-213828

However, the 1,3-butylene glycol products obtained from these purification methods still contain by-products and have a problem of having an odor. In addition, there is also a problem that coloring occurs with time.

Therefore, an object of the present invention is to provide a high-purity 1,3-butylene glycol product which is colorless and odorless and is less likely to be colored with time.

As a result of diligent studies to achieve the above object, the present inventors have improved the method for producing crude 1,3-butylene glycol to obtain high purity, which is odorless and colorless and is less likely to be colored with time. It was found that the 1,3-butylene glycol product of No. 1 was obtained. The present invention has been completed based on these findings.

That is, in the present invention, in the gas chromatography analysis under the following conditions,
When the relative retention time of the peak of 1,3-butylene glycol is 1.0, the area ratio of the peak appearing in the range of 2.3 to 2.4 is 1000 ppm or less. Providing products.
(Conditions for gas chromatography analysis)
Analytical column: A column in which the stationary phase is dimethylpolysiloxane (thickness 1.0 μm × length 30 m × inner diameter 0.25 mm)
Temperature rise conditions: After raising the temperature from 80 ° C. to 120 ° C. at 5 ° C./min, the temperature is raised to 160 ° C. at 2 ° C./min and held for 2 minutes. Further, the temperature is raised to 230 ° C. at 10 ° C./min and held at 230 ° C. for 18 minutes.
Sample introduction temperature: 250 ° C
Carrier gas: Gas flow rate of helium column: 1 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 280 ° C

The 1,3-butylene glycol product preferably has an APHA of 60 or less after being held at 180 ° C. for 3 hours in an air atmosphere.

The 1,3-butylene glycol in the above 1,3-butylene glycol product is preferably a reduced product of at least one compound selected from the group consisting of acetaldehyde, paraaldol, and aldoxane.

Since the 1,3-butylene glycol product of the present invention is colorless and transparent and is less likely to be colored with time, it is suitably used for applications such as cosmetics and moisturizers.

It is a flowchart of the manufacturing method (purification method) about the 1,3-butylene glycol product of this invention. It is a chart of the gas chromatography analysis of the 1,3-butylene glycol product in Example 1. It is a chart of the gas chromatography analysis of the 1,3-butylene glycol product in Comparative Example 1.

The 1,3-butylene glycol product of the present invention has a relative retention time of 2.3 to 2 when the relative retention time of the peak of 1,3-butylene glycol is 1.0 in the gas chromatography analysis under the following conditions. It is characterized in that the area ratio of the peak appearing in the range of 0.4 is 1000 ppm or less.

(Conditions for gas chromatography analysis)
Analytical column: A column in which the stationary phase is dimethylpolysiloxane (thickness 1.0 μm × length 30 m × inner diameter 0.25 mm)
Temperature rise conditions: After raising the temperature from 80 ° C. to 120 ° C. at 5 ° C./min, the temperature is raised to 160 ° C. at 2 ° C./min and held for 2 minutes. Further, the temperature is raised to 230 ° C. at 10 ° C./min and held at 230 ° C. for 18 minutes.
Sample introduction temperature: 250 ° C
Carrier gas: Gas flow rate of helium column: 1 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 280 ° C

The area ratio of the peak is, for example, preferably 500 ppm or less, more preferably 250 ppm or less, further preferably 150 ppm or less, still more preferably 100 ppm or less, particularly preferably 50 ppm or less, and most preferably 20 ppm or less. In the present invention, the "area ratio" of the peak means the ratio of the area of a specific peak to the sum of the areas of all the peaks appearing on the chart. In addition, all peaks are, for example, peaks appearing when the relative retention time of the peak of 1,3-butylene glycol is 1.0 and the analysis is continuously stopped until the relative retention time is 7.8. Means everything. When the area ratio of the peak is in the above range, the generation of odor and the coloring due to aging tend to be reduced.

In the gas chromatography analysis under the above conditions, when the relative retention time of the peak of 1,3-butylene glycol is 1.0, the relative retention time is as a component corresponding to the peak appearing in the range of 2.3 to 2.4. For example, an acetal form of 1,3-butylene glycol and acetaldol can be mentioned. The acetal form is a by-product having a boiling point higher than that of 1,3-butylene glycol. That is, the 1,3-butylene glycol product of the present invention preferably has a low content of the acetal compound as a by-product.

In the 1,3-butylene glycol product of the present invention, the area ratio of the peak of 1,3-butylene glycol in the gas chromatography analysis under the above conditions is preferably, for example, 99.5% or more, more preferably 99. It is 7.7% or more, more preferably 99.8% or more, and particularly preferably 99.9% or more. When the area ratio of the peak is in the above range, the generation of odor and the coloring due to aging tend to be reduced.

In the 1,3-butylene glycol product of the present invention, the relative retention time is 1.6 to 1 when the relative retention time of the peak of 1,3-butylene glycol in the gas chromatography analysis under the above conditions is 1.0. The area ratio of the peak appearing in the range of .8 is, for example, preferably 2000 ppm or less, more preferably 1000 ppm or less, still more preferably 600 ppm or less, and particularly preferably 200 ppm or less. When the area ratio of the peak is in the above range, the generation of odor and the coloring due to aging tend to be reduced. The lower limit of the area ratio may be, for example, 10 ppm, 20 ppm, 50 ppm, or 100 ppm.

In the gas chromatography analysis under the above conditions, when the relative retention time of the peak of 1,3-butylene glycol is 1.0, the relative retention time appears in the range of 1.6 to 1.8 as a component corresponding to the peak. For example, a hydride of a trimer of a raw material (acetaldehyde) can be mentioned. That is, the 1,3-butylene glycol product of the present invention preferably has a low content of the hydride as a by-product.

The Hazen color number (APHA) of the 1,3-butylene glycol product of the present invention after being held at 180 ° C. for 3 hours in an air atmosphere is not particularly limited, but is preferably 60 or less, more preferably 60 or less, for example. It is 40 or less, more preferably 30 or less. The APHA after holding at 100 ° C. for 75 days in an air atmosphere is not particularly limited, but is preferably 40 or less, more preferably 30 or less, still more preferably 20 or less, and particularly preferably 15 or less. For any of the above APHAs, the lower limit may be, for example, 1, 3, 5, or 10.

The APHA of the 1,3-butylene glycol product of the present invention (APHA of the 1,3-butylene glycol product not stored at high temperature) is not particularly limited, but is preferably 20 or less, more preferably 10 or less, for example. , More preferably 5 or less. The lower limit of APHA may be, for example, 1 or 2.

For APHA of the 1,3-butylene glycol product of the present invention, the ratio of APHA after holding at 180 ° C. for 3 hours to APHA before holding [(APHA after holding at 180 ° C. for 3 hours) / (APHA before holding)] Is not particularly limited, but is preferably 15 or less, and more preferably 12 or less. Further, the above ratio may be 1 or more, and may be 2 or more and 5 or more.

For APHA of the 1,3-butylene glycol product of the present invention, the ratio of APHA after holding at 100 ° C. for 75 days to APHA before holding [(APHA after holding at 100 ° C. for 75 days) / (APHA before holding)] Is not particularly limited, but is preferably 10 or less, and more preferably 7 or less. Further, the above ratio may be 1 or more, and may be 2 or more.

The 1,3-butylene glycol in the 1,3-butylene glycol product of the present invention is, for example, (1) a reduced product of acetoaldoles, (2) a hydrolyzate of 1,3-butylene oxide, and (3) erythritol. Selective hydrocracked product, (4) Selective water addition to butadiene, (5) N-butanol-3-one hydride, (6) 1-butanol-3-one hydride, (7) Examples thereof include hydrides of 3-hydroxy-1-butanoic acid, (8) hydrides of β-butyrolactone, and (9) hydrides of diketen. The 1,3-butylene glycol of the present invention may be one or a mixture of two or more of the above (1) to (9).

The 1,3-butylene glycol in the 1,3-butylene glycol product of the present invention is preferably (1) a reduced form of acetaldehydes. The reduced form of acetaldehyde is preferably a liquid phase reduced form of acetaldehyde from the viewpoint of the yield of 1,3-butylene glycol. The reason is that acetaldehydes have a high boiling point, acetaldehydes are heat-unstable, and they easily undergo a dehydration reaction at high temperatures to become crotonaldehyde, etc., and further, dehydration reactions at high temperatures. The reduction reaction (hydrogenation reaction) is due to the fact that the former reaction rate is high. That is, when acetaldehydes are reduced in gas phase, it is necessary to raise the temperature inside the reaction system. However, when acetaldehydes are exposed to high temperatures, a dehydration reaction occurs to generate crotonaldehyde, etc., and the subsequent reduction reaction causes butanol. And other by-products are produced. Therefore, the yield of the target 1,3-butylene glycol is relatively lowered. Therefore, in order to obtain a high-purity 1,3-butylene glycol product, it is preferable to carry out liquid phase reduction rather than gas phase reduction. Here, 1,3-butylene glycol as a reduced form of acetaldehyde can be rephrased as 1,3-butylene glycol obtained by a method of reducing acetaldehyde with hydrogen. Similarly, 1,3-butylene glycol as a liquid phase reducer of acetaldehyde can be rephrased as 1,3-butylene glycol obtained by a method of hydrogen reducing acetaldehyde in the liquid phase. Further, 1,3-butylene glycol as a hydrolyzate of 1,3-butylene oxide can be paraphrased as 1,3-butylene glycol obtained by hydrolyzing 1,3-butylene oxide.

Generally, when 1,3-butylene glycol is produced, a by-product is produced in the production process. For example, when 1,3-butylene glycol is produced by hydrogen reduction of acetaldehydes, low boiling point substances (low boiling point compounds) having unsaturated bonds such as acetaldehyde, butylaldehyde, crotonaldehyde, acetone, and methyl vinyl ketone are used. These condensates, condensates of 1,3-butylene glycol and the above low boiling point substances (for example, acetal compounds of 1,3-butylene glycol and acetaldehyde) and the like are by-produced. In addition, acetal form of crotonaldehyde and 1,3-butylene glycol, acetal form of acetaldehyde and 1,3-butylene glycol, acetal form of acetaldehyde or acetaldehyde and trimeric hydride of acetaldehyde, etc. Is a by-product.

And these by-products have properties as a color-causing substance and an odor-causing substance. It is not certain whether the acetal form is a color-causing substance or an odor-causing substance, and it is possible that the acetal form has both properties. Specifically, although the acetal body itself is unlikely to be an odor-causing substance, there is a possibility that an odor-causing substance may be generated due to aging or heating. In addition, the acetal form may generate acetaldehyde by hydrolysis, which can be said to be a coloring-causing substance because it is an odor-causing substance and has an oxidation (coloring) promoting action. Here, the color-causing substance is defined as including not only a substance that actually has a hue itself but also a substance that changes to a substance having a hue over time. Further, the odor-causing substance is defined as including not only a substance that actually emits an odor but also a substance that changes to a substance that emits an odor over time.

It is difficult to completely remove these by-products, particularly the acetal form described above, even by using conventional purification means such as distillation. This is because, in the purification stage of crude 1,3-butylene glycol, the crude 1,3-butylene glycol is subjected to high temperature conditions and alkaline treatment to produce new by-products. it is conceivable that. Therefore, as described above, the 1,3-butylene glycol products of Patent Documents 1 to 6 have an odor because they contain many by-products, and are further colored with time. Therefore, in order to obtain a high-purity 1,3-butylene glycol product, it is not enough to improve the method for purifying the crude 1,3-butylene glycol, but also to improve the method for producing the crude 1,3-butylene glycol. It can be said that it is necessary to do.

Hydrogenated raw materials containing acetaldehyde are used for the production of 1,3-butylene glycol. The acetaldols are not particularly limited as long as they are compounds that become 1,3-butylene glycol by hydrogen reduction, and are, for example, acetaldol, its cyclized dimer paraaldol, and a kind of cyclic trimer of acetaldehyde. Examples thereof include aldoxane and a mixture thereof.

The method for producing acetaldehydes (for example, acetaldehyde and paraaldol) is not particularly limited, but for example, even those obtained by the aldol condensation reaction of acetaldehyde in the presence of a basic catalyst can be obtained by thermal decomposition of aldoxane or the like. It may be an aldol. The crude reaction solution containing acetaldehydes obtained by the above reaction may be neutralized with an acid and used for the production of 1,3-butylene glycol. In addition to acetaldehyde, such reaction crude liquid may contain acetaldehyde, crotonaldehyde, other aldehyde components, low boiling point substances, high boiling point substances such as aldehyde dimers and trimmers, water, salts and the like. In the present specification, a compound having a boiling point lower than that of 1,3-butylene glycol may be referred to as a "low boiling point substance", and a compound having a boiling point higher than that of 1,3-butylene glycol may be referred to as a "high boiling point substance". ..

If necessary, the crude reaction solution may be subjected to pretreatment such as dealcohol distillation, dehydration distillation, desalting, demineralization, etc. to remove by-products such as unreacted acetaldehyde and crotonaldehyde. .. Examples of the pretreatment method include distillation, adsorption, ion exchange, heating to a high boiling point, decomposition and the like. For distillation, various distillation methods such as reduced pressure, normal pressure, pressure, azeotrope, extraction, and reaction can be used.

The content of acetaldehyde in the hydrogenated raw material is not particularly limited, but is preferably, for example, 50% by weight or more (for example, 50 to 99% by weight), and more preferably 60% by weight or more (for example, 60 to 98% by weight). ), More preferably 65 to 98% by weight, particularly preferably 80 to 95% by weight, and most preferably 85 to 95% by weight. When the content of acetaldehydes is within the above range, impurities contained in the crude 1,3-butylene glycol tend to be reduced.

The hydrogenated raw material may or may not contain water, but it is preferably contained from the viewpoint of the purity of the 1,3-butylene glycol product. The content of water in the hydrogenated raw material is not particularly limited, but is, for example, 2% by weight or more, more preferably 5% by weight or more, still more preferably 10% by weight or more, and particularly preferably 15% by weight or more. The upper limit may be, for example, 50% by weight, 40% by weight, or 35% by weight. When the water content is within the above range, the acetal form of 1,3-butylene glycol and acetaldehyde contained in the obtained crude 1,3-butylene glycol is reduced, so that the finally obtained 1, The purity of 3-butylene glycol products tends to be high. This is because the acetal form is hydrolyzed to 1,3-butylene glycol due to the hydrogenation raw material containing water to some extent, and the symbiotic acetaldol is reduced to 1,3-butylene glycol. Due to becoming.

Hereinafter, a method for producing crude 1,3-butylene glycol will be described. The present production method is characterized in that crude 1,3-butylene glycol is obtained by reducing a hydrogenated raw material containing acetaldehydes in the presence of a hydrogenated catalyst.

Examples of the hydrogenated catalyst include Raney nickel and the like. The hydrogenated catalyst can be used after being turbid or filled, but it is preferably used after being turbid. The amount of the hydrogenated catalyst used is not particularly limited, but is preferably 1 to 30 parts by weight, more preferably 4 to 25 parts by weight, still more preferably 8 to 20 parts by weight, based on 100 parts by weight of the hydrogenated raw material. , Particularly preferably 12 to 18 parts by weight. The amount of hydrogen used in the reduction reaction is not particularly limited, but is preferably 0.5 to 40 parts by weight, more preferably 1 to 30 parts by weight, still more preferably 4 to 20 parts by weight, based on 100 parts by weight of the hydrogenated raw material. It is by weight, particularly preferably 8 to 12 parts by weight. The pressure (total pressure) in the reaction system in the reduction reaction is not particularly limited, but is preferably 150 to 500 atm, more preferably 180 to 450 atm, still more preferably 200 to 400 atm, and particularly preferably 250 to 350 atm. The ratio of the hydrogen pressure (partial pressure of hydrogen) to the total pressure in the reaction system is not particularly limited, but is preferably 80% or more (80 to 100%) of the total pressure, and more preferably 85 to 99. It is 9%, more preferably 90 to 99.5%, and particularly preferably 95 to 99%. The hydrogen pressure (partial pressure of hydrogen) in the reaction system is not particularly limited, but is preferably 100 to 500 atm, more preferably 150 to 450 atm, still more preferably 150 to 400 atm, and particularly preferably 200 to 350 atm. The reaction temperature in the reduction reaction is not particularly limited, but is preferably 110 to 140 ° C, more preferably 120 to 140 ° C, for example. The reaction time (residence time) in the reduction reaction is not particularly limited, but is preferably, for example, 30 to 300 minutes, more preferably 80 to 280 minutes, and even more preferably 120 to 250 minutes.

When the amount of hydrogenation catalyst used for the reduction reaction, the amount of hydrogen, the hydrogen pressure in the reduction reaction, the reaction temperature, and the reaction time (residence time) are within the above ranges, the acetoaldoles can be converted to 1,3-butylene glycol. The reaction rate (hydrogenation rate) is improved. Therefore, for example, the acetalization reaction between 1,3-butylene glycol and acetaldehyde is reduced, and the 1,3-butylene glycol product of the present invention with high purity tends to be obtained. This tendency is particularly strongly influenced by the hydrogen pressure in the reduction reaction. That is, when the hydrogen pressure in the reduction reaction is within the above range, the reaction rate (reduction rate) from acetaldehydes to 1,3-butylene glycol is remarkably improved, and as a result, 1,3-butylene glycol and aceto The acetal form with aldol is reduced, and the 1,3-butylene glycol product of the present invention having high purity can be obtained. This reaction can be carried out in a batch system, a semi-batch system, or a continuous system.

The crude 1,3-butylene glycol obtained by hydrogenation of the hydrogenated raw material is subjected to, for example, a dehydration step, a desalting step, a dehigh boiling point distillation step, an alkali reaction step, a dealkali step, and a distillation step. , 1,3-butylene glycol product can be obtained.

The content of the high boiling point of the crude 1,3-butylene glycol is not particularly limited, but is preferably 0.1 to 20% by weight, more preferably 1 to 15% by weight, still more preferably 2 to 2% by weight. It is 10% by weight. When the content of the high boiling point substance in the crude 1,3-butylene glycol is within the above range, the amount of by-products contained in the finally obtained 1,3-butylene glycol product tends to be reduced.

The content of the high boiling point in the crude 1,3-butylene glycol after the dehigh boiling point distillation step is 1.0% by weight or less, preferably 0.5% by weight or less. By using crude 1,3-butylene glycol having a low content of high boiling point, there is no formation of low boiling point due to decomposition reaction of high boiling point even if it is heat-treated with a base in the alkaline reaction step. Very few. As a result, there is a tendency to obtain extremely high quality 1,3-butylene glycol products that are not colored and are less colored over time.

FIG. 1 is a flow sheet of an apparatus showing an example of an embodiment for obtaining the 1,3-butylene glycol product of the present invention. A is a dehydration tower and is related to the dehydration process. B is a desalination tower and is related to the desalination process. C is a dehigh boiling point distillation column and is related to the dehigh boiling point distillation step. D is an alkaline reactor and is related to the alkaline reaction step. E is a dealkali tower and is related to the dealkali step. F is a product distillation column and is related to the distillation process. A-1, B-1, C-1, E-1, and F-1 are capacitors. A-2, C-2, and F-2 are reboilers. Hereinafter, an example of an embodiment for obtaining the 1,3-butylene glycol product of the present invention using the present flow sheet will be described.

The crude 1,3-butylene glycol (corresponding to "X-1") obtained by hydrogenation of the hydrogenated raw material is supplied to the dehydration column A. In the dehydration column A, water is distilled from the top of the column by distillation, and a crude 1,3-butylene glycol stream containing 1,3-butylene glycol is obtained from the bottom of the column. The crude 1,3-butylene glycol flow is supplied to the desalting column B. In the desalting column B, a crude 1,3-butylene glycol flow after desalting is obtained from the top of the column by distillation, and salts, high boiling point substances and the like are discharged from the bottom of the column.

The crude 1,3-butylene glycol flow after desalting is supplied to the dehigh boiling point distillation column C. In the dehigh boiling point distillation column C, the high boiling point is discharged from the bottom of the column. On the other hand, a crude 1,3-butylene glycol flow after the dehigh boiling point is obtained from the top of the column. The crude 1,3-butylene glycol distilled by the dehigh boiling point distillation column C is supplied to an alkaline reactor (for example, a flow tube type reactor) D and subjected to base treatment. In the alkaline reactor D or upstream thereof, 0.05 to 10% by weight, preferably 0.1 to 1.0% by weight, of the base is added to the crude 1,3-butylene glycol flow after the dehigh boiling point. .. If the amount of the base added exceeds 10% by weight, the base tends to precipitate in the distillation column, piping, etc., causing clogging. In addition, decomposition reactions of high boiling point compounds may occur, and by-products tend to be generated on the contrary. If it is less than 0.05% by weight, the effect of decomposing by-products is small, which is not preferable.

The base added in the alkali reactor D or upstream thereof is not particularly limited, but for example, an alkali metal compound is preferable. Examples of the alkali metal compound include caustic soda, caustic potash, (heavy) sodium carbonate, and (heavy) potassium carbonate, but from the viewpoint of reducing by-products contained in the finally obtained 1,3-butylene glycol product. , Caustic soda, caustic potash are preferred. A solid base may be added as it is, but it is preferable to add the base as an aqueous solution in order to promote contact with the target liquid in terms of operation. The above-mentioned bases may be used alone or in combination of two or more.

The reaction temperature in the alkaline reactor D is not particularly limited, but is preferably 90 to 140 ° C, more preferably 110 to 130 ° C, for example. If the reaction temperature is less than 90 ° C, a long reaction residence time is required, which increases the reactor capacity and is uneconomical. If the reaction temperature exceeds 140 ° C, the final 1,3-butylene is obtained. The increase in coloration of glycol products. The reaction residence time is, for example, preferably 5 to 120 minutes, more preferably 10 to 30 minutes. If the reaction residence time is less than 5 minutes, the reaction will be insufficient and the quality of the finally obtained 1,3-butylene glycol product will deteriorate, and if the reaction residence time exceeds 120 minutes, a large reactor will be required. This is disadvantageous from the viewpoint of economic efficiency because the equipment cost is high.

After leaving the alkaline reactor D, the reaction crude liquid flow is supplied to the de-alkali column (thin film evaporator) E, and bases and the like are removed from the bottom of the column by evaporation. On the other hand, a crude 1,3-butylene glycol flow after debasement can be obtained from the top of the de-alkali tower E. As the evaporator used in the dealkalizing column E, a natural flow type thin film evaporator and a forced stirring type thin film evaporator having a short residence time are suitable for the purpose of suppressing the heat history to the process fluid.

In the evaporator used for the de-alkali column E, for example, the top of the column is evaporated under a reduced pressure of 100 torr or less, preferably 5 to 20 torr. The temperature of the evaporator is preferably 90 to 120 ° C., for example. A crude 1,3-butylene glycol stream containing a low boiling point distilled from the top of the column is supplied to the product distillation column F.

Examples of the product distillation column F include a perforated plate tower, a bubble bell tower, etc., but a filling tower with low pressure loss filled with sluzer packing, Melapack (both are trade names of Sumitomo Heavy Industries, Ltd.), etc. More preferred. This is because 1,3-butylene glycol is thermally decomposed at a high temperature (for example, 150 ° C. or higher) to produce a low boiling point product which is a coloring component, so that the distillation temperature is lowered. This is also because the same effect occurs when the heat history (residence time) of 1,3-butylene glycol is long. Therefore, the reboiler to be adopted is preferably one having a short residence time of the fluid on the process side, for example, a thin film evaporator such as a natural flow type thin film evaporator or a forced stirring type thin film evaporator.

When the concentration of the low boiling point substance in the charged liquid of the product distillation column F is 5% by weight or less, the theoretical plate number is preferably 10 to 20 stages, for example. The charging liquid is preferably supplied from the top of the column to a position of 20 to 70% of the height of the column. In the distillation in the product distillation column F, the pressure at the top of the column is preferably 100 torr or less, more preferably 5 to 20 torr. The reflux ratio is preferably, for example, 0.5 to 2.0.

In FIG. 1, in the preparation of the product distillation column F, the liquid obtained by condensing the top vapor of the dealkalitan column E with the condenser E-1 is fed, but the top vapor from the dealkalising column E is directly distilled into the product. It may be fed to Tower F. In the product distillation column F, impurities such as low boiling point substances are distilled off from the top of the column, and 1,3-butylene glycol as a product is obtained from the bottom of the product distillation column F (corresponding to “Y”).

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. The "part" used in the examples means a "part by weight" unless otherwise specified.

[Example 1]
A method for producing 1,3-butylene glycol will be described with reference to FIG.
For 100 parts of an acetoaldole solution containing 30% by weight of water as a raw material (a mixed solution of 70 parts of acetoaldole and 30 parts of water), 10 parts of hydrogen was charged into a liquid phase hydrogen reduction reactor, and 15 parts of lane nickel was added as a catalyst. In addition, the reactor was maintained at 135 ° C. and 300 atm for liquid phase hydrogen reduction. The liquid after the reaction was neutralized with caustic soda after separating the catalyst, and alcohols were removed to obtain crude 1,3-butylene glycol (1).

Crude 1,3-butylene glycol (1) (corresponding to “X-1” in FIG. 1) was charged into the dehydration column A. In the dehydration tower A, water is extracted from the top of the column with respect to 100 parts of the charged liquid, 15 parts of fresh water is added as reflux water, the pressure is set to 50 torr, and the amount of water is 0.5% by weight or less from the bottom of the column. Butylene glycol (2) was obtained. The water extracted from the top of the tower was discharged (corresponding to "X-2" in FIG. 1).

Next, crude 1,3-butylene glycol (2) was charged into the desalting tower B. In the desalting column B, salt, a high boiling point substance, and a part of 1,3-butylene glycol were discharged as an evaporation residue from the bottom of the column (corresponding to "X-3" in FIG. 1). The amount of the evaporation residue discharged was 5 parts with respect to 100 parts of the charged liquid amount. On the other hand, crude 1,3-butylene glycol (3) containing 1,3-butylene glycol, a low boiling point substance, and a part of a high boiling point substance was obtained from the top of the column.

Next, crude 1,3-butylene glycol (3) was charged into the dehigh boiling point distillation column C. In the dehigh boiling point distillation column C, a high boiling point and a part of 1,3-butylene glycol were discharged from the bottom of the column (corresponding to "X-4" in FIG. 1). The discharge amount was 20 parts with respect to 100 parts of the charged liquid amount. On the other hand, 80 parts of crude 1,3-butylene glycol (4) containing a low boiling point was obtained from the top of the column. Next, crude 1,3-butylene glycol (4) was charged into the alkaline reactor D. At this time, a 10% by weight aqueous solution of caustic soda was added so that the concentration of caustic soda with respect to the charging liquid was 0.2% by weight. The reaction temperature in the alkaline reactor D was maintained at 120 ° C., and the reaction was carried out with a residence time of 20 minutes.

Next, the reaction crude liquid discharged from the alkali reactor D was charged into the dealkali tower E. In the de-alkali column E, caustic soda, a high boiling point substance, and a part of 1,3-butylene glycol were discharged from the bottom of the column (corresponding to "X-5" in FIG. 1). The discharge amount was 10 parts with respect to 100 parts of the charged liquid amount. On the other hand, 90 parts of crude 1,3-butylene glycol (5) containing 1,3-butylene glycol and a low boiling point substance was obtained from the top of the column.

Next, crude 1,3-butylene glycol (5) was charged into the product distillation column F. In the product distillation column F, 10 parts of a low boiling point substance and a part of 1,3-butylene glycol were distilled from the top of the column with respect to 100 parts of the charged liquid (corresponding to "X-6" in FIG. 1). , 90 parts of 1,3-butylene glycol product was obtained from the bottom of the column (corresponding to "Y" in FIG. 1).

As a result of gas chromatography analysis of the above-mentioned 1,3-butylene glycol product under the conditions described below, the peak in the relative retention time range of 2.3 to 2.4 was below the detection limit (10 ppm or less). It was. The area ratio of the peaks appearing in the relative retention time in the range of 1.6 to 1.8 was 130 ppm. When the time-dependent coloring test 1 was performed, the APHA was 21 after holding at 180 ° C. for 3 hours in an air atmosphere. Moreover, when the time-dependent coloring test 2 was performed, the APHA was 10 after being kept at 100 ° C. for 75 days in an air atmosphere. The APHA before these tests was 2. Furthermore, the score of the odor test was 1.

[Comparative Example 1]
As a result of gas chromatography analysis of 1,3-butylene glycol (product number: 13BGO) manufactured by Daicel Corporation under the conditions described below, the area ratio of peaks appearing in the relative retention time in the range of 2.3 to 2.4. Was 1137 ppm. The area ratio of the peaks appearing in the relative retention time in the range of 1.6 to 1.8 was 1010 ppm. When the time-dependent coloring test 1 was performed, the APHA was 80 after holding at 180 ° C. for 3 hours in an air atmosphere. Moreover, when the time-dependent coloring test 2 was performed, the APHA was 46 after being kept at 100 ° C. for 75 days in an air atmosphere. The APHA before performing these tests was 4. Furthermore, the score of the odor test was 2.

[Gas chromatography analysis]
Gas chromatographic analysis of the target 1,3-butylene glycol product was performed under the following conditions. The chart of the gas chromatography analysis of 1,3-butylene glycol in Example 1 is shown in FIG. In addition, a chart of gas chromatography analysis of 1,3-butylene glycol in Comparative Example 1 is shown in FIG.
(Conditions for gas chromatography analysis)
Analyzer: Shimadzu GC2010
Analytical column: Agent J & W GC column-DB-1 (column whose stationary phase is dimethylpolysiloxane, film thickness 1.0 μm x length 30 m x inner diameter 0.25 mm, manufactured by Agilent Technologies, Inc.)
Temperature rise conditions: After raising the temperature from 80 ° C. to 120 ° C. at 5 ° C./min, the temperature is raised to 160 ° C. at 2 ° C./min and held for 2 minutes. Further, the temperature is raised to 230 ° C. at 10 ° C./min and held at 230 ° C. for 18 minutes.
Sample introduction and temperature: Split sample introduction method, 250 ° C
Split gas flow rate and carrier gas: 23 mL / min, helium column gas flow rate and carrier gas: 1 mL / min, helium detector and temperature: flame ionization detector (FID), 280 ° C.
Injection sample: 0.2 μL 80 wt% 1,3-butylene glycol product aqueous solution

[Time-dependent coloring test 1]
The target 1,3-butylene glycol product was placed in a wide-mouthed bottle, sealed tightly, and kept in a constant temperature bath set at 180 ° C. for 3 hours. Using a color difference meter (“ZE6000” manufactured by Nippon Denshoku Kogyo Co., Ltd.), the Hazen color number (APHA) of the 1,3-butylene glycol product after holding was measured using a quartz cell having an optical path length of 10 mm.

[Time-dependent coloring test 2]
The target 1,3-butylene glycol product was placed in a wide-mouthed bottle, sealed, and kept in a constant temperature bath set at 100 ° C. for 75 days. Using a color difference meter (“ZE6000” manufactured by Nippon Denshoku Kogyo Co., Ltd.), the Hazen color number (APHA) of the 1,3-butylene glycol product after holding was measured using a quartz cell having an optical path length of 10 mm.

[Odor test]
The target 1,3-butylene glycol product is placed in a wide-mouth reagent bottle, sealed tightly, and allowed to stand at room temperature. Then, the odor is quickly sniffed in the air, and the relative evaluation with the following 1,3-butylene glycol product is performed. I gave a score.
1: No odor 2: Slight odor

A: Dehydration column B: Desalting column C: Dehigh boiling point distillation column D: Alkaline reactor E: Dealkali column F: Product distillation column A-1, B-1, C-1, E-1, F- 1: Condenser A-2, C-2, F-2: Reboiler X-1: Coarse 1,3-butylene glycol X-2: Water (drainage)
X-3: Salt, high boiling point, and part of 1,3-butylene glycol X-4: High boiling point and part of 1,3-butylene glycol X-5: Caustic soda, high boiling point, and 1, Part of 3-butylene glycol X-6: Low boiling point and part of 1,3-butylene glycol Y: 1,3-butylene glycol product

Claims (3)

In gas chromatography analysis under the following conditions
When the relative retention time of the peak of 1,3-butylene glycol is 1.0, the area ratio of the peak appearing in the range of 2.3 to 2.4 is 1000 ppm or less. Product.
(Conditions for gas chromatography analysis)
Analytical column: A column in which the stationary phase is dimethylpolysiloxane (thickness 1.0 μm × length 30 m × inner diameter 0.25 mm)
Temperature rise conditions: After raising the temperature from 80 ° C. to 120 ° C. at 5 ° C./min, the temperature is raised to 160 ° C. at 2 ° C./min and held for 2 minutes. Further, the temperature is raised to 230 ° C. at 10 ° C./min and held at 230 ° C. for 18 minutes.
Sample introduction temperature: 250 ° C
Carrier gas: Gas flow rate of helium column: 1 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 280 ° C The 1,3-butylene glycol product according to claim 1, wherein the APHA after holding at 180 ° C. for 3 hours in an air atmosphere is 60 or less. The 1,3 according to claim 1 or 2, wherein the 1,3-butylene glycol in the 1,3-butylene glycol product is a reduced product of at least one compound selected from the group consisting of acetaldehyde, paraaldol, and aldoxane. 3-Butylene glycol product.

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