JPS6045165B2 - Method for purifying polyhydric alcohol - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for purifying a polyhydric alcohol containing 3-methylpentane-1,3,5-triol and/or 3-methyl-2-hydroxymethylbutane-1,3-diol as a main component. Regarding.

More specifically, 4,4-dimethyl-1,3-dioxane is produced as a by-product when 4,4-dimethyl-1,3-dioxane is produced from isobutene and formaldehyde by Prince reaction, and 4,4-dimethyl-1,
3-methylpentane-1,3,5-triol represented by the following formula (I) and/or 3 represented by the following formula (■) obtained by hydrolyzing a compound having a higher boiling point than 3-dioxane -Methyl-2-hydroxymethylbutane-1,3-diol (hereinafter, the compounds of formulas (I) and (■) are simply referred to as triol) as a main component. HC)-C
H2-CH2~C-CH2-CH2-OHOH...
...(I) CH3-C-℃H-CH2-OH)) OHCH2OH...(■) 4,4-dipmethyl-1,3-dioxane (hereinafter abbreviated as DMD) from isobutene and formaldehyde It is known that a compound with a higher boiling point than DMD (hereinafter abbreviated as residol) is produced as a by-product during production.

Bu11.50c, Chim, France804~8
11 (1964), residol is mainly 1.35
- It is a mixture of a number of complex derivatives of dioxane compounds, formaldehyde and alcohols. It is also known that polyhydric alcohols such as triols are produced when residol is hydrolyzed with an acidic catalyst such as sulfuric acid (Japanese Patent Publication No. 39-1421).

Typical compounds that produce the triol by hydrolysis in residol are represented by the following structural formulas (■) and (■).

(In the formula, R is an alcohol residue, and n is a positive integer.) However, there are many types of components produced by the hydrolysis of residol using an acidic catalyst, and all of them include triols, formaldehyde, and other compounds that are produced in large amounts. Because it is not necessarily stable under the reaction conditions and involves successive side reactions,
Hydrolyzed products are strongly colored and odorized.

Residol and/or dioxane alcohols that are partial hydrolysis products of residol (formula (■) above, (
■) in R=H, . When a compound with n=0) is treated with boric acid, very few side reactions occur during the treatment process, and as a result, the coloring and odor of the polyhydric alcohol produced are greatly reduced (Japanese Patent Laid-Open No. 50-62981). (Refer to Japanese Patent Publications No. 2003-11002 and No. 50-62915) However, it is still not possible to completely remove coloring and odor components from the polyhydric alcohol produced by distillation alone. Moreover, triols have extremely high boiling points (boiling point of 3-methylpentane-1●3●5-triol: 200T C/26T!rl!LHgl3-methyl-2-hydroxymethylbutane-1,3-diol boiling point: 200 C/46Tn1nHg), and thermally
Since it is not necessarily chemically stable, when attempts are made to purify crude polyhydric alcohols containing many impurities by distillation using ordinary industrial equipment, secondary coloring and odor may occur, which is undesirable. In addition to the above-mentioned distillation methods, recrystallization methods, methods using ion exchange resins, methods using activated carbon or other adsorbents, and the like have been used singly or in combination depending on the purpose for purifying polyhydric alcohols.

However, high boiling point, high viscosity (5750I). P. /20℃
), it is difficult to purify triols that have a low freezing point (-30°C) and are not highly stable against acids using only these methods. For example, the adsorption decolorization method using activated carbon is effective for decolorization, but it poses problems not only in the loss of the polyhydric alcohol itself due to adsorption to the activated carbon, but also in the disposal of a large amount of water-containing waste activated carbon after use. Furthermore, problems such as triol decomposition occur due to elution and accumulation of trace salts contained in the activated carbon. The present inventors have conducted intensive studies on a method that does not cause the above-mentioned problems of conventional methods and can almost completely remove evening coloring and odor components contained in polyhydric alcohols. There are roughly two types of coloring components and coloring source components contained in polyhydric alcohols obtained by hydrolysis. , (abbreviated as BK), and others have the property of being difficult to extract into MIBK, but remaining in the bottom when the triol is distilled out by distillation. Extraction operation and steaming
We have discovered that polyhydric alcohols containing triols as main components can be effectively purified by combining distillation operations.

That is, the present inventors added water and MIBK to a polyhydric alcohol obtained by hydrolysis of Residol, brought them into sufficient contact, phase separated, and removed the water from the resulting aqueous phase to obtain a solution in the polyhydric alcohol. It has been shown that most of the coloring and odor components can be almost selectively extracted and transferred to MIBK@, and that the color components that are not removed even in the extraction operation can be removed as a bottom liquid by further distillation. I found it.

In an embodiment of the method of the present invention, the hydrolysis product of residol can be directly subjected to the extraction operation using MIBK, but from the viewpoint of purification operation and purification efficiency, the hydrolysis product is extracted from the triol in advance by a normal distillation operation. It is preferable to perform an extraction operation using MIBK after cutting off components having a low boiling point and components having a high boiling point.

MIBK extraction and separation of purified alcohol from crude polyhydric alcohol with low-boiling and high-boiling substances removed,
Either by diluting the crude polyhydric alcohol with water and contacting it with MIBK, separating the resulting MIBK phase and evaporating the water from the remaining aqueous phase, or mixing the crude polyhydric alcohol with MIBK and then removing the water. In addition, it is separated into two phases,
This is effectively carried out by evaporating water from the resulting aqueous phase. The amount of water present in the extraction system during the process of the present invention is 0.5 to 5.5% relative to the crude polyhydric alcohol.
0 times amount (weight), especially 1.0 to 3. The weight (weight) is preferred. Although it is possible to carry out the method of the present invention even beyond this range, in order to carry it out effectively and economically, it is necessary to carry out the method even if the range exceeds 0.
5-5. Weight (weight) is preferred. In other words, if the amount of water is less than 0 times the amount (weight), the polyhydric alcohol phase (aqueous phase)
Not only will this cause problems with important factors in the extraction operation, such as the viscosity of If the amount exceeds 5.0 times the amount (weight), the amount of water to be removed by evaporation will increase.
- Undesirable due to energy disadvantage. MlB
The amount of K used is 0.3 to 3.0% relative to the crude polyhydric alcohol. @
The amount (capacity) is preferably 0.5 to 2. @Quantity (capacity)
is appropriate. If the amount of MIBK used is too small, the removal efficiency of coloring and odor components in one extraction will be low, and on the other hand, if the amount of MIBK used is too large, the amount of MIBK recovered and circulated after extraction will increase. , and the amount of polyhydric alcohol transferred to the MYBK phase also increases. The extraction temperature is preferably room temperature to 80°C, more preferably room temperature to 60°C. There is no advantage to extracting at higher or lower temperatures. Polyhydric alcohol phase (aqueous phase) after extraction separation
Water dissolved in the polyhydric alcohol phase and dissolved MIBK can be removed by evaporating it under normal pressure or reduced pressure, and as a result, a nearly colorless polyhydric alcohol is obtained as a residual liquid. Further, by evaporating under reduced pressure, a polyhydric alcohol with higher purity and no coloring or odor can be obtained as an evaporated product.

The MIBK phase after extraction and separation is separated into water-containing MIBK as a distillate and bottom liquid by simple distillation.

The separated MIBK can be recycled and reused in the crude polyhydric alcohol extraction process. On the other hand, the remaining polyhydric alcohol in the pot residue can be transferred to the aqueous phase by contacting the pot residue with an equal to three times the amount of water, and the resulting polyhydric alcohol aqueous solution is similar to MIBK. , can be recycled to the crude polyhydric alcohol extraction step. On the other hand, the remaining liquid from the pot after removing the residual polyhydric alcohol is mainly composed of colored and odor components, and is usually incinerated. As described above, by the method of the present invention, "DMD" is
The process of decolorizing and deodorizing the polyhydric alcohol obtained from the multi-component high-boiling residual oil that is produced as a by-product during the production of alcohol can be made continuous, which has great industrial merits.

In addition, the method of the present invention not only has a greater purification effect than the conventional method, but also has excellent thermal coloring stability of purified polyhydric alcohol, and furthermore, it does not generate industrial waste such as waste activated carbon that is generated when activated carbon decolorization method etc. are used. It has great industrial significance. Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 150 q1 crude triol (hereinafter referred to as crude triol A: Gardner color number 17) obtained by distilling off components with a lower boiling point than the triol from the hydrolysis product of residol, 300 y water, and 50 ml MIBKl were mixed and stirred vigorously for 10 minutes. After that, the mixture was allowed to stand still, and after one powder, the MIBK phase was separated and removed.

After adding 150 ml of MIBK to the obtained aqueous phase again and performing the same extraction and separation operations, water was removed from the aqueous phase using an evaporator at 80 to 130°C/2 CymHg.
Furthermore, from the obtained can liquid 1, 140 to 145% of triol was added.
The mixture was evaporated at C/1 to 1.5 Hg. The Hazen color number of the obtained triol (145y) was 20, and the temperature at 50°C
No odor was detected. Example 2 Crude triol (hereinafter referred to as crude triol B: Gardner color number 4) obtained by further single evaporation of the crude triol A used in Example 1 to remove higher boiling point components than the triol (hereinafter referred to as crude triol B: Gardner color number 4) 150
g, water 300q and MIBK75Tnl mixed, 1
After stirring vigorously, the mixture was allowed to stand still, and after 5 minutes, the MIBK phase was separated and removed.

After repeating the above extraction and separation operation twice by adding 75 ml of MIBK to the obtained aqueous phase, water was removed from the obtained aqueous phase at normal pressure until the liquid temperature reached 1300C, and further at this temperature up to 25wnHg. Water was removed under reduced pressure.
The Hazen color number of the triol obtained as a bottom liquid was 20. This triol was further added under reduced pressure (140 to 14
5. C/1~1.5W1! As a result of evaporation to FtHg), a purified triol (146y) with a Hazen color number of 10 was obtained. No odor was detected in this product at 50°C. Example 3 Crude triol BlOOyl water 200f and MIB
KlOOml was mixed and stirred vigorously for 1C@, then stopped, and after 5 minutes, the MIBK phase was separated and removed.

Water was removed from the resulting aqueous phase at normal pressure until the liquid temperature reached 130° C., and at this temperature, water was removed under reduced pressure to 25 WfLHg. The resulting bottom liquid was evaporated under reduced pressure to obtain purified triol (97f), which had a Hazen color number of 10 and was odorless at room temperature. Example 4 A mixture of crude triol BlOOf and MIBKlOOml was heated to 60° C. with stirring to form a homogeneous phase, and then 200 y of 60° C. warm water was added and stirred once to separate into two phases.

After 5 minutes, the aqueous phase was heated at normal pressure until the liquid temperature reached 130° C. to remove water, and at this temperature, the water was further removed under reduced pressure to 25.7 rr1 nHg.

When the triol in the resulting canned liquid was evaporated under reduced pressure,
An odorless triol (97f1) with a Hazen color number of 15 was obtained. Comparative Example Add 200f of water to the crude triol BlOOy used in Example 2.
After adding 5 y of activated carbon and stirring the mixture at 60°C, the activated carbon was removed by filtration.

Water was removed from the bottom liquid under normal pressure until the internal temperature reached 130° C., and at this temperature, water was sufficiently removed under reduced pressure to 257 r$THg. As a result, the Hazen color number of the triol obtained as a bottom liquid was 20. This triol was further added under reduced pressure (140-145.C/1-1.5W!!IHg)
The Hazen color number of triol (92y) obtained by evaporation was 15. Reference Example Triols having a Hazen color number of 15 obtained in Example 4 and Comparative Examples were heated in air to 165°C for 4 hours, and then their Hazen color numbers were measured.
The triol purified by the method of the present invention had less coloration.

Claims (1)

[Scope of Claims] 1 A by-product during the production of 4,4-dimethyl-1,3-dioxane from isobutene and formaldehyde, and 4
・In a method for purifying a polyhydric alcohol obtained by hydrolyzing a compound having a higher boiling point than 4-dimethyl-1,3-dioxane, the polyhydric alcohol is brought into contact with methyl isobutyl ketone in the presence of water. 1. A method for purifying polyhydric alcohols, which comprises subsequent phase separation and removal of water from the resulting aqueous phase. 2 A by-product when producing 4,4-dimethyl-1,3-dioxane from isobutene and formaldehyde, and 4
・In a method for purifying a polyhydric alcohol obtained by hydrolyzing a compound having a higher boiling point than 4-dimethyl-1,3-dioxane, the polyhydric alcohol is brought into contact with methyl isobutyl ketone in the presence of water. 1. A method for purifying a polyhydric alcohol, which is characterized in that the polyhydric alcohol is obtained as an evaporated product from a residual liquid obtained by subsequent phase separation and distillation of water from the resulting aqueous phase.