JPH11228577A - Production of high-purity spiroglycol - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce the subject compound scarcely containing discoloring impurities with a small amount of a solvent used at a high recovery ratio of a spiroglycol by dissolving the spiroglycol in a solvent comprising a specific amide compound and a specified aromatic compound and then recrystallizing the spiroglycol. SOLUTION: (A) An unpurified spiroglycol represented by formula I is dissolved in a solvent comprising (B) one or more kinds of amide compounds represented by formula II (R1 to R3 are each H or the like) (e.g. N,N- dimethylformamide) and (C) one or more kinds of aromatic compounds represented by formula III [R4 is H or the like; (m) denotes the number of substituent groups and is 0-4] (e.g. toluene), preferably at 50-150 deg.C and the resultant solution is then cooled to recrystallize the spiroglycol and afford the objective compound. The weight ratio of the components B/C is preferably (20/80) to (80/20). The compound is useful as a polymerization raw material for polycarbonate resins, etc., utilized as a plastic optical material in which importance is attached to appearance such as various lenses or optical disk substrates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying spiroglycol to obtain highly pure 3,9-bis (2-hydroxy-1,1).
The present invention relates to a method for producing (1-dimethylethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane. 3,9-bis (2-hydroxy-1,1-
(Dimethylethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane has the following chemical structure, and this compound is hereinafter referred to as spiroglycol in the present specification.

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Spiroglycol is used as a raw material for synthesizing low molecular weight compounds such as urethane, ester, thiol and ether compounds, and as a raw material for polymerizing high molecular weight compounds such as polyurethane, polyester, polyether polyol, polycarbonate and epoxy resin. Are synthetic lubricating oils, crosslinking agents, reactive diluents, plasticizers, adhesives, modifiers,
As a raw material for antioxidants, light stabilizers, etc.
It is useful as a raw material for chemical resistance, heat resistance, abrasion resistance and impact resistance resin.

[0003] Among them, copolymerized polycarbonate resins obtained by polycondensation of spiroglycol, bisphenols and carbonic acid diester have excellent balance of transparency and optical properties, and are suitably used as plastic optical materials such as various lenses, prisms and optical disk substrates. You can do it.

[0004]

2. Description of the Related Art Spiroglycol is produced by an acetalization reaction between hydroxypivalaldehyde and pentaerythritol. For example, toluene,
A method in which the reaction is carried out while azeotropically dehydrating using a solvent such as xylene (US Pat. No. 2,945,008), a method in which pentaerythritol is dissolved in concentrated hydrochloric acid, and then the reaction is carried out while gradually adding hydroxypivalaldehyde (Japanese Patent Application Laid-Open No. H11-163,837). Showa 48
JP-A-96590), a method using water as a reaction medium (U.S. Pat. No. 3,092,640), a method using an organic solvent as a reaction medium (JP-A-7-215979), and the like.

[0005] However, spiroglycol obtained by any of the methods, when used as a raw material without purification, may cause coloration of the product, deterioration of physical properties, and the like. Above all, when unpurified spiroglycol (hereinafter, referred to as crude spiroglycol) is subjected to a transesterification reaction with bisphenols and carbonic acid diester, there is a problem that the obtained copolymerized polycarbonate resin is significantly colored. It is not preferable in appearance as an optical material.

[0006] In order to obtain a copolymerized polycarbonate resin with less coloring to the extent that it is difficult to identify with the naked eye, it is necessary to purify and use crude spiroglycol. As a purification method,
Distillation, sublimation, recrystallization, solvent extraction and the like are typical purification methods. However, in the distillation method, the sublimation method and the solvent extraction method, the purification of the crude spiroglycol is insufficient, and the coloring of the copolymerized polycarbonate resin cannot be prevented. In the recrystallization method, it is possible to obtain a high-purity spiroglycol that gives a copolymer polycarbonate resin with less coloring by using a polar solvent such as methanol, dioxane, or N, N-dimethylformamide. Large amount,
Alternatively, there is a problem that the recovery rate of spiroglycol is low, or a large number of recrystallization operations are required, and there is a problem that a large purification cost is required industrially. A recrystallization solvent system that solves such a problem and uses a small amount of solvent and has a high spiroglycol recovery rate has not been found.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the prior art and to provide a recrystallization solvent which uses a small amount of solvent and has a high spiroglycol recovery rate.

[0008]

Means for Solving the Problems In purifying spiroglycol by the recrystallization method, the present inventors have conducted intensive studies on a recrystallization solvent that uses a small amount of solvent and has a high spiroglycol recovery rate. The present inventors have found that the above problem can be solved by using a solvent comprising an alkyl-substituted amide (hereinafter referred to as an amide compound) and an aromatic compound as a recrystallization solvent, and have reached the present invention.

That is, the present invention uses a solvent comprising at least one amide compound represented by the following general formula (1) and at least one aromatic compound represented by the following general formula (2) as a recrystallization solvent. It is characterized by the following.

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[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As the amide compound represented by the above formula (1), specifically, formamide, acetamido, propionamide, butylamide, N-methylformamide, N-butylformamide, N-methylacetamido, N-methylacetamido Methylpropionamide, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-dimethylacetamide
N-dimethylpropionamide, N, N-diethylformamide, N, N-diethylacetamide, N, N-diethylpropionamide, N, N-dipropylformamide, N, N-dipropylacetamide, N, N-methylethyl Formamide and the like are exemplified. Among them, N, N-dimethylformamide and N, N-dimethylacetamide are preferably used.

Specific examples of the aromatic compound represented by the above formula (2) include benzene, toluene, xylene, trimethylbenzene, tetramethylbenzene, ethylbenzene, diethylbenzene, triethylbenzene, n-propylbenzene, isopropylbenzene and diisopropylbenzene. -N-propylbenzene, diisopropylbenzene, n-butylbenzene, di-tert-butylbenzene, monochlorobenzene, tetralin and the like are exemplified, and among them, toluene and xylene are preferably used.

The solvent used in the present invention comprises at least one of the above-mentioned amide compounds and at least one of the aromatic compounds, and two or more of each may be used as a mixture.

In the present invention, the weight ratio of the amide compound to the aromatic compound (aromatic compound / amide compound)
Is from 10/90 to 90/10. If the weight ratio is less than 10/90, the amount of the mixed solvent used is undesirably large. The weight ratio is 90/10
If it is larger, the recovery rate of spiroglycol is low, and impurities cannot be sufficiently removed, which is not preferable. More preferably, the weight ratio of the amide compound to the aromatic compound is from 20/80 to 80/20.

The recrystallization operation is carried out by a known method in which crude spiroglycol is dissolved in a mixed solvent by heating and then cooled.

As the dissolving tank, it is preferable to use a vessel equipped with a jacket and a stirrer. Dissolution tank material is glass lining,
Inexpensive materials such as iron and stainless steel are used, but glass lining or stainless steel is preferable in order to prevent mixing of iron.

The dissolving method is a method in which crude spiroglycol is dissolved in an amide-based solvent by heating and then an aromatic hydrocarbon-based solvent is added. Or a method in which crude spiroglycol is dissolved by heating in a mixed solvent prepared in advance. The temperature of the solution after dissolution is preferably from 50 to 150 ° C, more preferably from 70 to 110 ° C, in order to increase the recrystallization yield.

The precipitation of the crystals is performed by completely dissolving the crude spiroglycol and then cooling the mixture to room temperature or below room temperature. The cooling method may be either standing or stirring, but it is preferable to stir in industrial operation. A refrigerant may or may not be used. When a refrigerant is used, the temperature of the refrigerant is preferably -10 to 40C. The cooling time is preferably 2 hours or more, and more preferably 6 hours or more, in order to sufficiently precipitate crystals.

The amount of the mixed solvent used is selected so that the slurry concentration of the crude spiroglycol precipitated by recrystallization is 10 to 50% by weight. If the slurry concentration is less than 10%, the yield of crude spiroglycol per recrystallization is small, resulting in poor efficiency. If the slurry concentration exceeds 50%, stirring becomes difficult, and the amount of mother liquor entrapped due to the attachment of crystals increases, which makes cleaning difficult, which is not preferable.

The filtration of the crystals is performed by a known method selected from natural filtration, pressure filtration, and reduced pressure filtration. A filter having a mesh of 0.5 to 20 μm is suitably used, and paper, cloth, glass, Teflon, ceramics or the like is used as a material. The obtained cake is desirably washed in order to sufficiently remove the mother liquor and improve the purity of the crystals. Washing is performed using a mixed solvent used for recrystallization or a poor solvent in which an aromatic hydrocarbon solvent is larger than the mixed solvent used for recrystallization, and a washing solvent 1/20 to 2 times the amount of the solvent used for recrystallization. It is preferably carried out 1 to 5 times in an amount.

In order to obtain spiroglycol having a desired purity, the above-mentioned recrystallization operation may be repeated twice or more.

The solvent is removed from the obtained cake by a drying operation. Drying is performed under normal pressure drying or vacuum drying. Atmospheric pressure drying is performed at a drying temperature of 80 to 120 ° C, and vacuum drying is performed at a drying temperature of 60 to 100 ° C and 1 mmHg. As the dryer, a shelf-type dryer, a conical dryer, or the like is used. The material of the portion that comes into direct contact with spiroglycol is preferably glass lining or stainless steel.

[0022]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited by the following examples. The parts are parts by weight, the purity of spiroglycol is the percentage of simple area by gas chromatography, the weight average molecular weight (Mw) is the molecular weight in terms of styrene measured by GPC, and YI is the abbreviation of yellow index, which indicates the degree of coloring (small) Less coloring).

Production Example (Synthesis of Crude Spiroglycol) Unreacted isobutyraldehyde and triethylamine are distilled off from an aldol reaction product solution obtained by reacting isobutyraldehyde and formaldehyde with triethylamine as a catalyst at 65 ° C. and 300 mmHg. Thus, a reaction solution containing 57.8% of hydroxypivalaldehyde was obtained. 463 parts of pentaerythritol, 80 parts of 35% hydrochloric acid and 2500 parts of water were added to 1260 parts of the hydroxypivalaldehyde solution, and the reaction was carried out at a reaction temperature of 80 to 85 ° C. and a stirring speed of 400 rpm for 3 hours. After the completion of the reaction, the slurry was neutralized with a 10% aqueous solution of sodium hydrogen carbonate, and after filtration, the cake was washed with 1500 parts of water. Thereafter, vacuum drying was performed at 80 ° C. for 12 hours to obtain 848 parts of crude spiroglycol (82.0% based on pentaerythritol, purity 95.0%). This crude spiroglycol was used in all of the following Examples and Comparative Examples.

Example 1 100 parts of crude spiroglycol was added to a mixed solvent consisting of 100 parts of N, N-dimethylformamide and 100 parts of toluene, and the mixture was heated to 97 ° C. and dissolved. This was allowed to cool naturally at room temperature, and allowed to stand for 12 hours to precipitate crystals. The obtained crystals were filtered and N, N-dimethylformamide 6.3.
The mixture was washed four times with a mixed solvent consisting of 6.3 parts of toluene and 6.3 parts of toluene, and then vacuum-dried at 80 ° C. for 6 hours. 86 parts of the purified spiroglycol thus recovered was 99.0% pure.

30.4 parts of the above purified spiroglycol,
2,2-bis (4-hydroxyphenyl) propane 2
2.8 parts, 43.3 parts of diphenyl carbonate and 5 * 10-5 parts of sodium bicarbonate were charged into a reactor equipped with a stirrer and a distilling apparatus, and heated to 180 ° C. under a nitrogen atmosphere to obtain 30 parts.
Stirred for minutes. Thereafter, the degree of vacuum was adjusted to 150 mmHg, and at the same time, the temperature was raised to 200 ° C. at a rate of 60 ° C./hr, and the transesterification reaction was performed while maintaining the temperature for 40 minutes. Further, the temperature was raised to 235 ° C. at a rate of 75 ° C./hr and maintained at that temperature for 10 minutes, and then the degree of pressure reduction was reduced to 1 mmHg or less over 1 hour. The reaction was carried out with stirring for a total of 6 hours. After the reaction was completed, nitrogen was blown into the reactor to return to normal pressure, and the copolymerized polycarbonate resin was taken out. Mw = 57
000. This copolymerized polycarbonate was press-molded into a disk having a thickness of 3 mm and a diameter of 40 mm, and the YI value was measured. As a result, it was 2.08, and it was difficult to identify coloring with the naked eye.

Example 2 100 parts of crude spiroglycol was added to a mixed solvent consisting of 65 parts of N, N-dimethylacetamide and 150 parts of toluene, and dissolved by heating to 104 ° C. This was allowed to cool naturally at room temperature, and allowed to stand for 12 hours to precipitate crystals. The resulting crystals were filtered and N, N-dimethylacetamide 4.0
And 4 times with a mixed solvent consisting of 9.4 parts of toluene and 9.4 parts of toluene, followed by vacuum drying at 80 ° C. for 12 hours. The recovered spiroglycol was 91 parts and had a purity of 99.2%.

The above purified spiroglycol was reacted in exactly the same manner as in Example 1, and the obtained copolymerized polycarbonate resin (Mw = 59400) was molded into exactly the same shape to form Y.
When the I value was measured, it was 2.04, and it was difficult to identify coloring with the naked eye. .

Example 3 100 parts of crude spiroglycol was added to a mixed solvent consisting of 100 parts of N, N-dimethylformamide and 50 parts of xylene, and the mixture was heated to 99 ° C. and dissolved. This was allowed to cool naturally at room temperature, and allowed to stand for 12 hours to precipitate crystals. The obtained crystals were filtered, and 6.3 parts of N, N-dimethylformamide was added.
After washing four times with a mixed solvent consisting of 3.1 parts of xylene,
Vacuum dried at 80 ° C. for 6 hours. The recovered spiroglycol was 82 parts and had a purity of 98.8%. The purified spiroglycol was reacted in exactly the same manner as in Example 1 to obtain a copolymerized polycarbonate resin (Mw = 5900).
No. 0) was molded in exactly the same shape and the YI value was measured. As a result, it was 2.15, and it was difficult to identify coloring with the naked eye. .

Comparative Example 1 100 parts of crude spiroglycol was added to a mixed solvent consisting of 100 parts of N, N-dimethylformamide and 100 parts of 2-butanone, and the mixture was heated to 93 ° C. and dissolved. This was allowed to cool naturally at room temperature, and allowed to stand for 12 hours to precipitate crystals. The obtained crystals are filtered and N, N-dimethylformamide6.
After washing four times with a mixed solvent consisting of 3 parts and 6.3 parts of 2-butanone, the resultant was vacuum-dried at 80 ° C. for 6 hours. The recovered spiroglycol was 88 parts and had a purity of 98.5%. The purified spiroglycol was reacted in exactly the same manner as in Example 1, and the resulting copolymerized polycarbonate resin (Mw
= 58800) was molded into the exact same shape, and the YI value was measured. The YI value was 3.16, and coloring was clearly observed with the naked eye.

Comparative Example 3 100 parts of crude spiroglycol was added to a mixed solvent consisting of 120 parts of N, N-dimethylformamide and 100 parts of ethyl acetate, and the mixture was heated to 95 ° C. and dissolved. This was allowed to cool naturally at room temperature, and allowed to stand for 12 hours to precipitate crystals. The crystals obtained are filtered and N, N-dimethylformamide 7.5.
After washing four times with a mixed solvent consisting of 6.3 parts of ethyl acetate and 6.3 parts of ethyl acetate, the resultant was vacuum-dried at 80 ° C. for 6 hours. The recovered spiroglycol was 88 parts and had a purity of 98.5%.

The purified spiroglycol was reacted in exactly the same manner as in Example 1, and the resulting copolycarbonate resin (Mw = 55500) was molded into exactly the same shape.
When the I value was measured, it was 3.00, and coloring was clearly observed with the naked eye.

Comparative Example 4 100 parts of crude spiroglycol was added to 100 parts of N, N-dimethylformamide and heated to 108 ° C. for dissolution. This was allowed to cool naturally at room temperature, and allowed to stand for 12 hours to precipitate crystals. The obtained crystals were filtered, washed four times with 6.3 parts of N, N-dimethylformamide, and dried in vacuo at 80 ° C. for 6 hours. The recovered purified spiro glycol is 7
7 parts, purity 98.4%. The purified spiroglycol was reacted in exactly the same manner as in Example 1, and the obtained copolymerized polycarbonate resin (Mw = 55700) was molded in exactly the same shape, and the YI value was measured. Clear coloring was observed.

Comparative Example 5 40 parts of crude spiroglycol was added to a mixed solvent consisting of 20 parts of N, N-dimethylformamide and 500 parts of toluene, and dissolved by heating to 105 ° C. This was allowed to cool naturally at room temperature, and allowed to stand for 12 hours to precipitate crystals. Since the amount of the amide-based polar solvent was less than 10%, the total amount of the mixed solvent was large, and the slurry concentration was 10% or less. The obtained crystals were filtered and N, N-dimethylformamide 1.3
After washing four times with a mixed solvent consisting of 31.3 parts of toluene and 31.3 parts of toluene, vacuum drying was performed at 80 ° C. for 6 hours. The recovered spiroglycol was 33 parts and had a purity of 99.0%.

The purified spiroglycol was reacted in exactly the same manner as in Example 1, and the resulting copolycarbonate resin (Mw = 59000) was molded into the same shape as Y
When the I value was measured, it was 2.10, and it was difficult to identify coloring with the naked eye. .

Comparative Example 6 160 parts of crude spiroglycol was added to 1560 parts of methanol and heated at 60 ° C. to dissolve. This was allowed to cool naturally at room temperature, and allowed to stand for 12 hours to precipitate crystals. The obtained crystals were filtered and washed four times with 100 parts of methanol.
Vacuum dried at 64 ° C. for 6 hours. The recovered purified spiro glycol was 68 parts and had a purity of 99.0%.

The purified spiroglycol was reacted in exactly the same manner as in Example 1, and the resulting copolycarbonate resin (Mw = 54900) was molded into exactly the same shape.
When the I value was measured, it was 3.19, and coloring was clearly observed with the naked eye.

[0037]

According to the present invention, spiroglycol having less coloring impurities can be efficiently and inexpensively obtained, and can be used in a wide range of applications from raw materials for synthesizing low molecular weight compounds to raw materials for synthesizing high molecular weight compounds. . In particular, in the copolycarbonate resin obtained by transesterification of spiroglycol, bisphenols, and carbonic acid diester, coloring is significantly reduced, so that the appearance of various lenses and optical disk substrates, especially the color tone, is regarded as important. It can be used for a wide range of applications as a plastic optical material.

Claims (4)

[Claims] (1) dissolving spiroglycol in a solvent comprising at least one compound represented by the following general formula (1) and at least one compound represented by the following general formula (2), followed by recrystallization; A method for producing high-purity spiroglycol, characterized by comprising: Embedded image (R ₁ , R ₂ and R ₃ are each a hydrogen atom or a carbon atom 4
These are the following alkyl groups. ) (R ₄ may form a ring with a hydrogen atom, a halogen atom or an alkyl group having 4 or less carbon atoms. M represents the number of substituents and is an integer of 0 to 4.) 2. The method of claim 1, wherein the spiroglycol is 3,9-bis (2-
Hydroxy-1,1-dimethylethyl) -2,4,8,
The method according to claim 1, which is 10-tetraoxaspiro [5.5] undecane. 3. A weight ratio [(1) / (2)] of at least one compound represented by the above general formula (1) to at least one compound represented by the above general formula (2) is 20 /. 80
2. The method of claim 1, wherein the ratio is ~ 80/20. 4. The method according to claim 1, wherein the spiroglycol is dissolved in a solvent at 50 to 150 ° C., and then cooled and recrystallized.