SU1659415A1 - Method for obtaining dianhydride of 4,6-disulfoisophtalic acid - Google Patents

Abstract

The invention relates to heterocyclic compounds, in particular to the preparation of 4,6-disulfoisophthalic acid dianhydride, which is used as a monomer for the synthesis of high-temperature and heat-resistant heterocyclo chain polymers. The goal is to simplify and intensify the process. The preparation is carried out by the reaction of the 4,6-disulfoisophthalic acid diammonium salt with an excess of chlorosulfonic acid with heating. Yield up to 98%.

Description

The invention relates to organic chemistry, specifically to an improved method for producing 4,6-disulfoisophthalic acid dianhydride, which is used as a monomer for the synthesis of high-temperature and heat-resistant heterocyclochain polymers.

A known method for producing 4,6-disulfoisophthalic acid dianhydride by reacting 4,6-disulfoisophthalic acid disodium salt with an excess of chlorosulfonic acid by heating for 3 hours, followed by extracting the target product by pouring the reaction mixture into crushed ice and filtering the precipitated crystals. The yield of the target product is 46% (theoretical), so pl. 229-230 ° C.

The disadvantages of this method are the low yield and the insufficient purity of the target product (mp 229-230 ° C), due to the inefficient release of the latter, i.e. by pouring the reaction mixture into crushed ice, which favors the hydrolysis of the target product, and also makes it difficult to remove and clean it.

In addition, the reaction time is relatively long (3 hours).

The purpose of the invention is to increase the yield and quality of 4,6-disulfoisophthalic acid dianhydride (m-dianhydride), shorten the duration and simplify the process.

According to the proposed method, 4,6-disulfoisophthalic acid diammonium salt is treated with excess chlorosulfonic acid when heated (110 ° C) for 1.0-2.0 h, followed by cooling the reaction mass to room temperature (15-20 ° C) and isolation of the target product by filtration.

The use of the diammonium salt with 4,6-disulfoisophthalic acid allows the desired product to be isolated in crystalline form by filtration, shortens the reaction time, prevents hydrolysis of the target product during isolation and thereby eliminates the loss of the latter, increases its purity and yield, i.e. simplifies the selection of the target product. .

 Example 1. In a round-bottom three-neck flask with a capacity of 150 ml, equipped with

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ate

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mechanical stirrer (through the shutter), thermometer and reflux condenser with calcium chloride tube, load 50 ml

0.76 mol) of freshly distilled chlorosulfonic acid, then 10.8 ± 1 g (0.03 mol) of a dry 4,6-disulfoisophthalic acid diammonium salt (in the form of a thin powdered powder). The salt immediately dissolves and the reaction mixture heats up spontaneously to 48-50 ° C. Then the flask is placed in an oil bath and the temperature is raised to 110 + 1 ° C for 20-30 minutes, which is then maintained under stirring for another 1.5 hours. At the beginning of heating 15 a homogeneous solution of light brown color is obtained, then white precipitates begin to precipitate needles. By the end of the experiment, when almost the entire product is deposited on the bottom of the flask, the reaction mixture is cooled to 15-20 ° C and the precipitate is filtered, washed several times with dry chloroform, dried in vacuum over solid caustic potash at 50-60 ° C. for 2 hours at 100-120 ° C to constant mass. Output 25 98% of theoretical, t, pl, 265-2bb ° C.

Example 2. The reaction conditions and the isolation of the desired product are the same as in Example 1, but stirring is continued at 110 ± 1 ° C for 2 hours. The yield of 4,6-disulfoisophthalic acid dianhydride is 98% of theoretical, m.p. 265 266 ° C.

Example 3. Carried out as in Example 1, but at a reaction temperature of 35 110 ± 1 ° C, stirring is continued in

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5 0 5

five

0

for 1 hour. The yield is 94% of the theoretical, m.p. 265-266 ° C.

Example 4. The preparation and isolation of 4,6-disulfoisophthalic acid dianhydride was carried out under conditions analogous to example 1, however, chlorosulfonic acid was taken in an amount of 55 ± 1 ml. Output 97%, so pl. 265-266 ° C.

Example 5. The conditions for preparation and isolation are similar to those in Example 1, but chlorosulfonic acid is taken in an amount of 45 ± 1 ml. Yield 90%, so pl. 265-266 ° C.

When using the proposed method, the yield of the target product is increased to 98% versus 46% by preventing losses during hydrolysis, carried out during the isolation and purification of the latter; 2 times the duration of the process of obtaining the desired product is reduced (1.0-2.0 hours versus 3.0-3.5 hours); the purity of the target product is increased (m.p. 265-266 ° C, in the prototype m.p. 229-2300 ° C) by preventing hydrolysis in the isolation step; the step of isolating the desired product is simplified.

Claims (1)

Invention Formula The method of producing 4,6-disulfoisophthalic acid dianhydride by reacting 4,6-disulfoisophthalic acid salt with an excess of chlorosulphonic acid when heated, characterized in that, in order to simplify and intensify the process, to increase the yield and quality of the target product, disulfoisophthalic acid using diammonium salt of 4,6-disulfoisophthalic acid.