SU418037A1 - Method for preparing 2,3,7,8-tetracarboxy dianhydride - Google Patents

Description

one

The invention relates to the field of producing new tetracarboxylic acid dianhydrides, which are used in the synthesis of polymers, for example, polnemides, and also as hardeners of epoxy alkyd resins.

A known method for producing 2,3,7,7,8-tetracarb JCI-10, lO-dimethylfevok dianhydride, sasiline by oxidation of 2,3,7,8,1OD01-hexamethylphenoxasiline, followed by anhydridization of the tetracarbonoyanoic acid thus obtained by known methods.

A method is proposed for the preparation of 2,3,7,8-tetracarbscy-1O, 1O-diphenylphenoxasiline dianhydride with the general formula

That is, 2,2-dibromo-4,4, 5,5-tetramethyldiphenylsids is reacted with n-butyl lithium. The process is desirable to conduct at a temperature of 25 kivevy

dietary ether for 4 hours, Mol | its ratio is 2,2-dibrom-4,4 to 5,5-tramethyl diphenyloxide and n-butyl lithium from 1: 2.1 to 1: 2.2. The resulting dipithium derivative of tetramethipiphenyloxide is condensed with an equimolar amount of diphenyldichlorosilane by the simultaneous addition of both components to an inert solvent, for example, diethyl ether,

temperature - 10-0 ° C, followed by boiling the mixture for 6-8 hours, hydrolysis with water, isolation and purification of the resulting 2,3,7,8-tetramethyl-10,10-diphenyl phenoxasiline.

The yield of the product purified by treatment with activated alumina and crystallized from high-boiling carbon, for example n-decane, reaches 48% of the theoretical value. The resulting 2,3,7,8-tetramethyl-10, 10-diphenylphenoxoxiline is oxidized to the corresponding tetracarboxylic acid. The oxidation is carried out in two stages with potassium permanganate in an alkaline aqueous pyridine medium at 85-1 ° C.

The yield of 2,3,7.8-tetracarboxy-10,10-diphenylphenoxasiline reaches 65% of the theoretical. The obtained tetracarboxylic acid is anhydrided by thermal treatment in a vacuum or by boiling in acetic anhydride.

ExampleJ,

A. Preparation of 2,2-dilitium-4,4,5,5-tetramethyldiphenoxide.

In a four-necked flask with a capacity of 2 liters, equipped with a stirrer, a reflux condenser, a dropping funnel and a tube for introducing nitrogen (all operations are performed under a nitrogen atmosphere), load 1 O 5 g

(O, 247 mol) 2,2-dibromo-4,4,5,5-tetramethyldiphenyloxide in 400 ml of o-xylene and 8OO ml of dry diethyl ether. 0.6 moles of n-butyl lithium in 500 ml of ether are added over 20 minutes, after which the mixture is boiled for 1 hour. The mixture is cooled to O-C and diluted to a volume of 2OOO with ether.

B. Preparation of 2,3,7,8-tetramethyl-10,1O-diphenylphene oxasiline a.

A 5-liter, 4-liter flask equipped with a stirrer, two graduated addition funnels, a reflux condenser, and a tube for introducing nitrogen are poured over 500 ml of ether and 200 ml of the resulting dilithium derivative. The flask is placed in a bath with a cooling mixture, the temperature of which is maintained at –1 ° C. Prepare a solution of 76 g (O, 3 mol) of diphenyldichlorosilane in 1OOO ml of ether, which is cooled to O C.

800 ml of ether solution of diphenyldichlorosilane and the remaining 1800 ml of solution of dilithium derivative are added to the reaction flask simultaneously for 2 hours. The remaining 2OO ml of ether solution of diphenyldichlorosilane is added over 1 hour.

after which the cooling bath is removed and the mixture is boiled for 6 hours. The reflux condenser is replaced with a descending condenser and approximately half of the solvent is distilled off, the mixture is cooled and poured into cooled 2% hydrochloric acid. The organic layer is separated, washed and dried. The ether and toluene are distilled off (toluene, preferably under vacuum). 12OO ml of heptane are gradually added, the mixture is heated to boiling, cooled and the precipitate is filtered.

Obtain 76 g of product with so pl. 1751955С. The obtained substance is dissolved in 2OOO ml of hot n-decane and treated with 2 g of activated alumina, filtered and cooled. The precipitation is filtered off, washed with hexane and dried.

Get 53,5 g (48% of theoretical) 2,3,7,8-tvtramethyl-10,1O-diphenylphenoxasiline with so pl. 200-202 0.

Found,%: O 83.18; 83.02; H 6.24; 6.18; 5 {6.83; 6.77.

Calculated,%: C 82.74; H 6.4; Si 6.92.

B. Preparation of 2,3,7,8-tetracarbox - -10,10-diphenylphenoxasiline.

In a four-necked flask with a capacity of 2 liters, equipped with a high-speed stirrer, a thermometer and a reflux condenser, 20.30 g of 2,3,7,8-tetrameti; l-1O, 1O-diphenylphenoxoxiline, 8OO ml of pyridine, 5 g of KOH and 20O ml of water are loaded . The mixture is heated with stirring to 9 ° -95 ° C and 19O g of potassium permanganate is added in small portions over 4 hours, with each subsequent portion being added after scavenging the previous one. After all the potassium permanganate is added, the mixture is boiled for 1 hour and filtered to manganese dioxide. Two manganese oxides are washed on the filter with hot pyridine and hot 3% potassium hydroxide solution. The filtrate and washings are combined and loaded into the pyridine distillation flask. The solution is evaporated until pyridine is completely freed by adding water several times to reduce the volume to 5OO ml. After distillation of all the pyridine, the oxidation is continued, for which, at 1 ° C, 4O g of potassium permanganate is added in portions. At the end of the addition, the mixture is boiled for 1 hour, the excess potassium permanganate is decomposed with 20 ml of ethanol. The mixture was filtered from manganese dioxide and the precipitate was washed with 100 ml of hot 3% -iioro potassium hydroxide solution. The filtrate and the washings were combined, treated with 5 g of KAD activated carbon and added to the solution concentrated hydrochloric acid to a strongly acidic reaction (). To complete

the selection of the product mixture is maintained at 24 hours. The precipitate is filtered off, washed with water and dried in a vacuum oven at lOQOC.

The output of 2,3,7,8-tetracarboxy-1O, 1O-diphenylphenoxoxiline 17 g (65% of theoretical), so pl. 235-238 ° C. The acid number of the obtained acid is 423, 427, 428 mg KOH per 1 g of the product (theoretical acid number 426.6).

G. Training of 2,3,7,8-tetracarbsxy-10, 10-dienesphenoxoxine dianhydride.

0.53 g of 2,3,7,8-tetracarboxy-10,1O-diphenylphenoxoxylne is heated at 2OO220 0 in vacuum (H-10-5-10 MHP and the dianhydride is sublimated.

0.46 g of 2,3,7,8 tetracarboxy-10, 1O-diphenylphenoxasiline dianhydride (yield 94% of the theoretical) are relieved; m.p. 2382390С.

5.27 g of 2,3,7,8-tetracarboxy-10,1O-diphenylphenoxoxiline is boiled for 15 minutes in 25 ml of acetic anhydride, the solution is filtered and cooled to -7O ° C for crystallization, and then kept at 12 hours. The precipitate of the dianhydride is filtered, washed with dry dioxane and dried at 150 ° C under vacuum.

3.8 g of 2,3,7,8-tetracarboxy-10, 10-diphenylphenoxasiline dianhydride are obtained (yield 78% of the theoretical); m.p. 237.5238, 50С.

The acid number of the obtained dananhydride (regardless of the anhydride method) is 454, 458, 459 mg KOH per 1 g of the product (theoretical acid number 457.9).

Found,%: C 68.89; 68.76; H 2.78; 2.73; Si 5.50; 5.62.

, 0, Si Calculated,%: C68,56; H2.86; Si 5.73.

Claims (1)

Invention Formula The method of preparing dianhydride 2,3,7,8-tetracarboxy-10,10-diphenylphenes-ssiline, characterized in that 2,2-dibromo-4, 4, 5, 5-etramethyldiphenyloxide is reacted with n-butyl lithium, followed by condensation of the resultant dilithium derivative with difenshschlorsilosilane, oxidation of the resulting 2,3,7,8-tetramethyl-1O, 1O-difennlfenszhsasilina and anhydride dibasic tetracarboxylic acid obtained by known methods.