JP5339238B2 - Synthesis of 2-dimethyl sodium sulfoterephthalate and addition of dimethyl terephthalate and ethylene glycol to the polycondensation system - Google Patents

Description

  In this study, 2-sulfoterephthalic acid was sulfonated with sulfur trioxide to form 2-sulfoterephthalic acid, excess sulfur trioxide was removed by a unique method, and 2-sulfoterephthalic acid was dimethylated with methanol. Esterification yields dimethyl 2-sulfoterephthalate, and dimethyl 2-sulfoterephthalate is sodium chloride via calcium hydroxide suspension aqueous solution treatment and sodium carbonate saturated aqueous solution treatment to obtain a purity of> 98.0% or It is in the field of synthesizing> 98.1% dimethyl sodium 2-sulfoterephthalate. Further, a field relating to the synthesis of linear polyethylene terephthalate having a sulfonic group by adding dimethyl sodium 2-sulfoterephthalate to a polycondensation system of dimethyl terephthalate and ethylene glycol, and studying the physical properties thereof. It is.

As a background art, 60% fuming sulfuric acid was added to terephthalic acid or an alkyl ester thereof (C _1-4 alkyl group) containing iron (II) chloride as a catalyst over 1 hour, and then heated to 180 ° C. for 12 hours. There is only a report (Patent Document 1) that 2-sulfoterephthalic acid or its alkyl ester (C _1-4 alkyl group) was obtained, and there is no other similar report. The reaction conditions for sulfonation of terephthalic acid described in this study are significantly different from those in Patent Document 1 and are non-catalytic, so they cannot be compared. In this study, dimethyl 2-sulfoterephthalate obtained by dimethyl esterification of 2-sulfoterephthalic acid was converted into a dimethylsodium 2-sulfoterephthalate aqueous solution through treatment with a calcium hydroxide suspension and saturated aqueous sodium carbonate. This is concentrated under reduced pressure. This method is unique to this research, and for the first time, it has succeeded in synthesizing a target product having a purity of> 98.0% or> 98.1%, which is a valuable result. On the other hand, a method for synthesizing linear polyethylene terephthalate having a sulfone group by adding dimethyl sodium 2-sulfoterephthalate to a polycondensation system of dimethyl terephthalate and ethylene glycol can be said to be a related technique. There are many patent documents that would be. That is, this is a patent document in which dimethyl sodium 5-sulfoisophthalate is added to a polycondensation system of dimethyl terephthalate and ethylene glycol to synthesize a non-linear polyethylene terephthalate having a sulfone group. Most of these have expired but have become indispensable references for this study. Patent Document 2, Patent Document 3, and Patent Document 4 were selected and referred to. That is, since the polycondensation reaction was performed under the same conditions using the same mol number of dimethyl sodium 2-sulfoterephthalate instead of dimethyl sodium 5-sulfoisophthalate shown in these patent documents, the results were compared. is there.

Japan Kokai Tokyo Koho JP 06340610; C.I. A. 122, 265028 (1994). Teijin, Japan Kokai 75 53396; C.I. A. 83, 133228 (1975). Kurarey, Japan 74 23267; C.I. A. , 82, 597884 (1975). Imperial Chem. Ind. , Ltd., Ltd. Belg. 648565; A. 64, 11375 (1966).

The problems to be solved by the invention are as follows. First, dimethyl sodium 2-sulfoterephthalate having a purity of> 98.0% is synthesized with good yield. Moreover, the synthesis method must be able to be carried out on a laboratory scale or an industrial scale. After achieving this, the next step is to use dimethyl sodium 2-sulfoterephthalate added to the polycondensation system of dimethyl terephthalate and ethylene glycol to have a sulfone group with less water repellency and improved dyeability. It is to synthesize linear polyethylene terephthalate. To date, dimethyl sodium 5-sulfoisophthalate has been used for similar purposes, but in this case the polymer molecule bends 60 ° in the middle. Comparison of linear polyethylene terephthalate (I) having a sulfone group and non-linear polyethylene terephthalate (II) having a sulfone group that bends 60 ° in the middle to find the characteristics of the former and use this This is the problem that this study tries to solve.

The synthesis of high purity dimethyl sodium 2-sulfoterephthalate is judged to be all. Each step of sulfonation of terephthalic acid, dimethyl esterification of the obtained 2-sulfoterephthalic acid, and sodium chlorination of the obtained dimethyl 2-sulfoterephthalate was repeatedly examined, and sodium sulfate of 2-dimethylsulfoterephthalate After measuring the content, we went back and started again from the sulfonation of terephthalic acid. Accordingly, a mixture of terephthalic acid and 2.5 mol equivalent of 60% fuming sulfuric acid described in the heading of claims is heated to 250 to 255 ° C. for 0.5 to 1.0 hour to 2-sulfoterephthalic acid. The description is obtained as a result of repeated trial and error over a long period of time. In sulfonation of isophthalic acid, isophthalic acid and 28% fuming sulfuric acid are heated to 190 ° C. for 2 hours, and then the reaction mixture is added to water and centrifuged (Patent Document 5). In sulfonation of terephthalic acid, it is extremely difficult and dangerous to add it to water after sulfonation and then perform centrifugation in the same manner. For this reason, the reaction mixture after sulfonation of terephthalic acid was converted into dimethyl ester as it was, and then salted out using a sodium hydroxide aqueous solution, a sodium chloride saturated aqueous solution or a sodium carbonate saturated aqueous solution, but no good results were obtained ( Example 1). Next, sulfur trioxide in the reaction mixture after sulfonation of terephthalic acid was converted to dimethyl sulfate using methanol, distilled under reduced pressure, the residue was converted to dimethyl ester, and then salted out in the same manner. With the exception of, good results were not obtained. The exception is that the purity of dimethyl sodium 2-sulfoterephthalate obtained by salting out using a saturated aqueous solution of sodium carbonate was 96.2%. For this reason, sulfur trioxide in the reaction mixture after sulfonation of terephthalic acid is converted into dimethyl sulfate using methanol and distilled under reduced pressure, and calcium hydroxide suspension in sodium chloride of dimethyl 2-sulfoterephthalate. A means for forming an aqueous solution of dimethyl sodium 2-sulfoterephthalate through a turbid aqueous solution treatment and a saturated aqueous sodium carbonate treatment was linked (Example 3). Further, regarding the addition of dimethyl sodium 2-sulfoterephthalate obtained in Example 3 to the polycondensation system of dimethyl terephthalate and ethylene glycol, it is described here as a means to solve as a problem. There is nothing.

Czech. 133635; C.I. A. 73, 109508 (1970)

  The content of sodium sulfate as an impurity in commercially available dimethyl sodium 5-sulfoisophthalate was measured and found to be 2.4%. The ones that are actually used industrially will be around this. That is, unless the content of sodium sulfate as an impurity in dimethyl sodium 2-sulfoterephthalate obtained in this study is <2.4%, the effect expected by the present invention cannot be obtained. In other words, if the purity of the dimethyl sodium 2-sulfoterephthalate obtained in this study is not> 97.6%, it is added to the polycondensation system of dimethyl terephthalate and ethylene glycol and is used as a straight line having a sulfone group. It is meaningless to synthesize a polyethylene terephthalate in the shape of a tube. To that end, the stages from terephthalic acid to dimethyl sodium 2-sulfoterephthalate were repeatedly studied to synthesize dimethyl sodium 2-sulfoterephthalate having a purity of> 98.0%. This is the first time that the effects of the present invention have been seen. That is, if there is a research example in which dimethyl terephthalate and ethylene glycol polycondensation system is added with dimethyl sodium 5-sulfoisophthalate to synthesize a non-linear polyethylene terephthalate having a sulfone group that bends 60 ° in the middle. Instead, dimethyl sodium 2-sulfoterephthalate was added to synthesize a linear polyethylene terephthalate having a sulfone group, and both results could be compared.

  First, in the synthesis of dimethyl sodium 2-sulfoterephthalate, the content of sodium sulfate as an impurity in the obtained product was measured and used as an indicator of purity. This is because, in repeated synthesis experiments, it was determined that sodium sulfate was the main impurity and that other impurities were hardly contained. This is apparent from the elemental analysis value of dimethyl sodium 2-sulfoterephthalate obtained in Example 3. In addition, the following experimental fact may be a proof of this. That is, when the reaction mixture containing dimethyl 2-sulfoterephthalate obtained in Example 1 was salted out with a saturated aqueous sodium chloride solution, the sodium sulfate content of the obtained dimethylsodium 2-sulfoterephthalate was 10%, The sodium chloride content was 0%.

  20 g (0.12 mol) of terephthalic acid and 40 g of 60% fuming sulfuric acid (0.3 mol as sulfur trioxide) are mixed, and the temperature is gradually raised while stirring to finally reach a temperature of 250 to 255 ° C. to 0.5 to 1. The reaction was performed by heating for 0 hour. Whether or not the reaction is completed can be roughly judged from the amount of sulfur trioxide being refluxed. The temperature of the water in the reflux condenser must be adjusted appropriately so that sulfur trioxide is smoothly refluxed. In addition, it is important to note that the reaction temperature and time are affected to some extent by the amount of terephthalic acid charged. After the reaction, 70 to 80 g (2.2 to 2.5 mol) of methanol was added and reflux-boiled for 3.5 hours. The results of salting out the obtained reaction mixture containing dimethyl 2-sulfoterephthalate will be described. When 50% aqueous sodium hydroxide solution is added to the reaction mixture, stirring becomes impossible during the process. The sodium sulfate content of dimethyl sodium 2-sulfoterephthalate obtained by adding a small amount of methanol and stirring and filtering was 7-8%. When 10-20% sodium hydroxide aqueous solution was added instead of 50% sodium hydroxide aqueous solution, dimethyl sodium 2-sulfoterephthalate was precipitated after a short time. The sodium sulfate content of this was> 50%. Moreover, when sodium chloride saturated aqueous solution was used and the reaction mixture was added thereto, dimethyl sodium 2-sulfoterephthalate was precipitated. This had a sodium sulfate content of 10% and a sodium chloride content of 0%. When a saturated aqueous sodium carbonate solution was used and added to the reaction mixture, dimethyl sodium 2-sulfoterephthalate was precipitated, but the yield was extremely low.

  Terephthalic acid was sulfonated in exactly the same way as in Example I. After the reaction, 12 g or more of methanol was added under cooling to convert excess sulfur trioxide to dimethyl sulfate. Dimethyl sulfuric acid was distilled off under reduced pressure, and then 60 to 70 g (1.9 to 2.2 mol) of methanol was added to the residue, followed by boiling at reflux for 3.5 hours. The results of salting out the obtained reaction mixture containing dimethyl 2-sulfoterephthalate will be described. When 50% aqueous sodium hydroxide solution is added to the reaction mixture, stirring becomes impossible during the process. The sodium sulfate content of dimethyl sodium 2-sulfoterephthalate obtained by adding a small amount of methanol and filtering was 8-9%. A saturated aqueous sodium chloride solution was used in place of the 50% aqueous sodium hydroxide solution, and when the reaction mixture was added thereto, dimethyl sodium 2-sulfoterephthalate was precipitated. The sodium sulfate content of this was> 10%. However, when a saturated aqueous sodium carbonate solution was used and added to the reaction mixture, dimethyl sodium 2-sulfoterephthalate was obtained in a relatively high yield. The sodium sulfate content of this product was 3.8%.

From the results of Example 2, it was considered that a method including converting excessive sulfur trioxide in the reaction mixture obtained by synthesizing 2-sulfoterephthalic acid into dimethyl sulfate and distilling it under reduced pressure would be successful. This method and the method of converting dimethyl 2-sulfoterephthalate into an aqueous solution of dimethylsodium 2-sulfoterephthalate via a calcium hydroxide suspension aqueous solution treatment and a sodium carbonate saturated aqueous solution treatment were linked. This is shown below. In the same manner as in Example 1, terephthalic acid was sulfonated. After the reaction, excess sulfur trioxide was converted to dimethyl sulfate in the same manner as in Example 2, and this was distilled under reduced pressure. The residue was boiled with methanol to obtain a reaction mixture containing dimethylic 2-sulfoterephthalate. . After most of the unreacted methanol was distilled off, the pH was adjusted to 7 by adding an aqueous calcium hydroxide suspension. When this is heated to 70 ° C. under reduced pressure for 1 hour, it reaches pH 6 position. The produced calcium sulfate was filtered off, and a saturated aqueous sodium carbonate solution was added to the filtrate to adjust the pH to 7 to 7.5. Further, it was confirmed that no new precipitate was formed even when a saturated aqueous solution of sodium carbonate was added, and then the resultant was treated with activated carbon and filtered. The filtrate was concentrated under reduced pressure, and the precipitated dimethyl sodium 2-sulfoterephthalate was filtered off. The sodium sulfate content of what was obtained was 1.8-1.9%. Moreover, the sodium sulfate content of what was obtained by evaporating and drying the filtrate of this time was 1.9 to 2.0%. That is, it is not necessary to fractionate the precipitated crystals during the vacuum concentration of the aqueous dimethyl sodium 2-sulfoterephthalate solution. It can be recrystallized with methanol-water (1: 1 volume ratio). Crude yield 76-84%. Elemental analysis before recrystallization (%) C35.9, H3.0, N <0.3. Elemental analysis after recrystallization (%) C40.0, H3.1, N <0.3; C 10 H 9 NaO 7 Calculated for S (%) C40.5, H3.1, N0.

In the same manner as in Example 1, terephthalic acid was sulfonated. After the reaction, the minimum amount of water necessary to convert the excess sulfur trioxide to sulfuric acid was added. Since this requires very skilled techniques, excess water may be added to remove excess afterwards. Next, 70 to 80 g (2.2 to 2.5 mol) of methanol was added and refluxed for 3.5 hours to obtain a reaction mixture containing dimethyl 2-sulfoterephthalate. In the same manner as in Example 3, the filtrate obtained after the treatment with activated carbon was concentrated under reduced pressure, and the precipitated dimethyl sodium 2-sulfoterephthalate was filtered off.
The sodium sulfate content of what was obtained was 2.7%. Moreover, the sodium sulfate content of what was obtained by evaporating to dryness the filtrate of this time was 4.0%. That is, it is not recommended to use a method in which excess sulfur trioxide after sulfonation of terephthalic acid is converted into sulfuric acid using water and then left in the reaction system.

  In the same manner as in Example 1, terephthalic acid was sulfonated. After the reaction, excess sulfur trioxide was converted to sulfuric acid using water, and water was further added to make the reaction mixture easy to filter through a glass filter. 2-sulfoterephthalic acid was filtered off, and water was removed from the filtrate by distillation under reduced pressure, and the precipitate obtained was combined with the previous one. 2-Sulfoterephthalic acid obtained by repeating this operation was combined and combined. 60-70 g (1.9-2.0 mol) of methanol was added thereto, and the mixture was boiled at reflux for 3.5 hours to obtain a reaction mixture containing dimethyl 2-sulfoterephthalate. In the same manner as in Example 3, the filtrate obtained after the treatment with activated carbon was concentrated under reduced pressure, and the precipitated dimethyl sodium 2-sulfoterephthalate was filtered off. The sodium sulfate content of what was obtained was 1.8-1.9%. Moreover, the sodium sulfate content of what was obtained by evaporating and drying this filtrate was 2.8%. That is, dimethyl sodium 2-sulfoterephthalate deposited at a relatively early stage of concentration under reduced pressure has a purity of> 98.1%, and therefore is shown in claim 3 of the claims.

０．３５ｄｌ・ｇ^−１（ο−クロロフェノ−ル、２５℃）であった。9.7 g (0.050 mol) of dimethyl terephthalate, 3.7 mg (0.015 mmol) of manganese (II) acetate tetrahydrate, and 0.34 g (0. (00115 mol), 3.9 mg (0.0134 mmol) of antimony (III) oxide, 6.6 mg (0.0804 mmol) of sodium acetate and 6.4 g (0.103 mol) of ethylene glycol were added to a distillation flask, The sample was heated to 170-230 ° C. for a long time at normal pressure while passing nitrogen gas through the tube. Most of the methanol produced by the reaction is distilled out

0.35 dl · g ⁻¹ (ο-chlorophenol, 25 ° C.).

た。A polyester was synthesized in the same manner as in Example 1. However, instead of heating at 275 ° C./1-3 mmHg in Example 6 for 3 hours, heating at 275 ° C./5-5 mmHg was performed for 3 hours. Obtained

It was.

ｄｌ・ｇ^−１（ο−クロロフェノ−ル、２５℃）であった。9.7 g (0.050 mol) of dimethyl terephthalate, 3.7 mg (0.015 mmol) of manganese (II) acetate tetrahydrate, 0.34 g (0.00115 mol) of commercially available dimethyl sodium 5-sulfoisophthalate, antimony oxide (III) 3.9 mg (0.0134 mmol), sodium acetate 6.6 mg (0.0804 mmol) and ethylene glycol 6.4 g (0.103 mol) were mixed, added to the distillation flask, and nitrogen gas was passed through it. Heated at normal pressure to 170-230 ° C for a long time. After most of the methanol produced by the reaction has distilled out

dl · g ⁻¹ (ο-chlorophenol, 25 ° C.).

［η］＝０．３７ｄｌ・ｇ^−１（ο−クロロフェノ−ル、２５℃）であった。10.0 g (0.0515 mol) of dimethyl terephthalate, 4 mg (0.022 mmol) of zinc acetate, 0.15 g (0.00051 mol) of dimethyl sodium 2-sulfoterephthalate obtained in Example 3, and ethylene glycol 8 0.0 g (0.129 mol) was mixed, added to the distillation flask, and heated to 170-230 ° C. at normal pressure for a long time while passing nitrogen gas through it. After most of the methanol produced by the reaction was distilled off, the distillation flask was cooled to 3 mg (0.01 mmol) of antimony (III) oxide, 45 mg (0.563 mmol) of titanium (IV) oxide and phosphorus. 5 mg (0.036 mmol) of trimethyl acid was added and again nitrogen gas

[Η] = 0.37 dl · g ⁻¹ (ο-chlorophenol, 25 ° C.).

った。Instead of 0.15 g (0.00051 mol) of dimethyl sodium 2-sulfoterephthalate in Example 9, 0.15 g (0.00051 mol) of commercially available dimethyl sodium 5-isophthalate was used. To obtain polyester. However, heating at 280 ° C./2 to 4 mmHg for 2.5 hours was used instead of heating at 280 ° C./1 to 2 mmHg for 2.5 hours in the final stage of the polycondensation reaction. Obtained

It was.

０．２１ｄｌ・ｇ^−１（ο−クロロフェノ−ル，２５℃）であった。Dimethyl terephthalate 17.9 g (0.0922 mol), calcium acetate monohydrate 17.03 mg (0.0966 mmol), antimony (III) oxide 8.33 mg (0.0285 mmol), 2- 3.033 g (0.01024 mol) of dimethyl sodium sulfoterephthalate and 14.33 g (0.231 mol) of ethylene glycol were mixed and added to the distillation flask. Heated for hours. After more than half of the methanol produced by the reaction has been distilled off, that is, the distillation flask is cooled leaving some of the produced methanol, 30 mg (0.31 mmol) of phosphoric acid is added thereto, and nitrogen gas is added again. After heating to 100-150 ° C./100 mmHg for a short time,

It was 0.21 dl · g ⁻¹ (ο-chlorophenol, 25 ° C.).

フェノ−ル、２５℃）であった。Instead of 3.033 g (0.01024 mol) of dimethyl sodium 2-sulfoterephthalate in Example 11, 3.033 g (0.01024 mol) of commercially available dimethyl sodium 5-sulfoisophthalate was used, and the others were similar to Example 11. To obtain a polyester. However, instead of heating at 281 to 288 ° C./1 to 2 mmHg for 2.5 hours in the final stage of the polycondensation reaction, at 281 to 286 ° C./1 to 2 mmHg

Phenol, 25 ° C.).

２４０〜２４２℃である。前者が５２°低融点であった。実施例９と実施例１０が比較可能な場合

あった。何れの場合においても２−スルホテレフタル酸ジメチルナトリウムを用いた前者が約５０°低融点となっている。すなわち、テレフタル酸ジメチルとエチレングリコ−ルの重縮合系に５−スルホイソフタル酸ジメチルナトリウムを添加するより２−スルホテレフタル酸ジメチルナトリウムを添加する方が、得られたスルホン基を有するポリエチレンテレフタレ−トが比較的低温度で熔融紡糸できて有利であることが示された。しかも、大きい抗張力を示すことが定性的ではあるが認められた。すなわち、より細い繊維になりうるのである。延伸についてははっきりしないが、その化学構造式からみてより延伸し易いことは明らかである。When it comes to industrial applicability, it means the applicability of the polymer obtained when dimethyl sodium 2-sulfoterephthalate is added to the polycondensation system of dimethyl terephthalate and ethylene glycol. This is a case where Example 6 and Example 8 can be compared. In Example 6

240-242 ° C. The former had a 52 ° low melting point. When Example 9 and Example 10 are comparable

there were. In any case, the former using dimethyl sodium 2-sulfoterephthalate has a low melting point of about 50 °. That is, the addition of dimethyl sodium 2-sulfoterephthalate to the polycondensation system of dimethyl terephthalate and ethylene glycol is more effective than the addition of dimethyl sodium 2-sulfoterephthalate to the obtained polyethylene terephthalate having a sulfone group. It has been shown to be advantageous that the melt can be melt spun at a relatively low temperature. Moreover, it was qualitatively shown to exhibit a high tensile strength. That is, it can be a finer fiber. Although it is not clear about stretching, it is clear that stretching is easier in view of its chemical structural formula.

  More importantly, a process has been found that can synthesize dimethyl sodium 2-sulfoterephthalate with a purity> 98.0% on both a laboratory scale and an industrial scale. It should be added to the polycondensation system of dimethyl terephthalate and ethylene glycol for the first time when a purity> 98.0% is synthesized, and compared with the case using dimethyl sodium 5-sulfoisophthalate. Is now possible.

2 is an IR spectrum (KBr tablet method) of dimethyl sodium 2-sulfoterephthalate obtained in Example 3. FIG. It is IR spectrum (KBr tablet method) of commercially available dimethyl sodium 5-sulfoisophthalate.

Claims (4)

  A mixture of terephthalic acid and 2.5 mol equivalents of 60% fuming sulfuric acid is heated to 250-255 ° C. for 0.5-1.0 hours to form a reaction mixture containing 2-sulfoterephthalic acid, and the excess in the reaction mixture The sulfur trioxide was changed to dimethyl sulfate and distilled under reduced pressure. The residue was boiled with methanol to reflux to dimethyl 2-sulfoterephthalate, and further treated with aqueous calcium hydroxide suspension and saturated aqueous sodium carbonate. A method of synthesizing dimethyl sodium 2-sulfoterephthalate having a purity of> 98.0% by preparing an aqueous solution of dimethyl sodium 2-sulfoterephthalate and concentrating the solution under reduced pressure to a state close to dryness.   A linear form having a sulfone group obtained by adding dimethyl sodium 2-sulfoterephthalate having a purity of> 98.0% obtained by the method shown in claim 1 to a polycondensation system of dimethyl terephthalate and ethylene glycol. Of synthesizing polyethylene terephthalate.   A mixture of terephthalic acid and 2.5 mol equivalent of 60% fuming sulfuric acid is heated to 250-255 ° C. for 0.5-1.0 hours to form a reaction mixture containing 2-sulfoterephthalic acid, which is excess in the reaction mixture. 2-sulfoterephthalic acid obtained by changing the sulfur trioxide of sulfuric acid to sulfuric acid, cooling by adding an appropriate amount of water, collecting the precipitated 2-sulfoterephthalic acid by filtration, and distilling off the water from the filtrate under reduced pressure. 2-sulfoterephthalic acid obtained by repeating the operation of combining the above with the previous one, combined and boiled with methanol to boil to dimethyl 2-sulfoterephthalate, and further treated with aqueous calcium hydroxide suspension and sodium carbonate Dimethyl 2-sulfoterephthalate aqueous solution having a purity of> 98.1% by concentrating under reduced pressure to give a dimethyl sodium 2-sulfoterephthalate aqueous solution by a saturated aqueous solution treatment. Method of synthesizing a potassium.   A linear shape having a sulfone group by adding dimethyl sodium 2-sulfoterephthalate having a purity of> 98.1% obtained by the method shown in claim 3 to a polycondensation system of dimethyl terephthalate and ethylene glycol. Of synthesizing polyethylene terephthalate.

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