SU597677A1 - Method of preparing phthalidenacetic acid - Google Patents

Description

methylenephthalide, which is spontaneously subjected to tar. The catalyst is not regenerated.

The day of increase in the output of phthalieneacetic acid and the supply of the process according to

: t1 to the predopagated method, the reaction of condensation of phthalic anhydride with acetic anhydride is carried out in the presence of a potassium phthalic acid dipotassium catalyst as a catalyst at a temperature of 115-125 ° C as follows:

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dH-UOOH / The regenerated catalyst in the form of a monocrystalline salt is converted to potassium salt and re-used. The yield of the target product per phthalic acid is 90-95%. The amount of regenerated phthalic acid wastes in the form of a monopotassium salt is 98-1OO%, Pr. In a three-fold flask ef KocTb X l, supplied with a mechanical mechanical stirrer, a reverse chiller and a thermometer, 150, О g technical f-halium anhydride (1 mol), ZOO ml acetic anhydride and the mixture are heated to 115-120 ° C, then the mixture is heated to 115-120 ° С, with vigorous stirring, 122.0 g of dry phthaloyanoic acid (0.5 mol) was added. Stirring is continued at 115125 ° C for 1 h, then another 61.0 g (0.25 mol) of dipotassium salt is added and stirred for 1 h under the same conditions (if the reaction mass thickens strongly, the exposure time is increased). Finally Another 61.0 g (0.25 mol) of dicarbonate salt and above are mixed, stirring at 115125 ° C for 4–3 h. The reaction mass is poured, with vigorous stirring, into the weighing {8OO ml), the temperature of which is 5-1 ° C. The reaction flask is washed with 200 ml of cold water, the contents are added to the total mass. Stirring is allowed; another 1015 minutes is allowed, after which phthalideneacetic acid is filtered and washed in several portions with 500 ml of hot water (5 ° –6 ° C). The filtrate is used in the recovery of waste. The precipitate is washed again.

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Claims (2)

(LOOK 500 ml of hot water, the resulting filtrate is not used further. Ft alide, acetic acid is dried first in the open air, then in a cupboard at a temperature not higher than 70-80 s. Get 175,0-185,0 g of the product light yellow colors, which is 90-95% in terms of phthalic anhydride. Phthalideneacetic acid obtained by the proposed method has a melting point in the sealed capillary of 242-245 ° C. When treated with silk and subsequent acidification with sulfuric acid, phthalideneacetic acid turns into -acetylbenzoic acid with mp 114-115 ° C. The filtrate contains Acetic acid, monopotassium phthalic acid and potassium acetate are distilled under vacuum. After obtaining 1OOO-11OO ml of a shoulder strap containing 15% acetic acid, the pasty residue is transferred to a beaker and cooled to 10-15 ° C. The precipitate is thoroughly drained under vacuum 150 ml of cold water are added to the flask.The resulting filtrate is subjected to further distillation under the same conditions and after obtaining 300350 ml of a shoulder strap, as in the first case, the residue is cooled and drained under vacuum. The mono potassium salt thus recovered is converted to a starch neutralization with a solution of caustic potash to a pH of 7.5. The resulting concentrate is transferred to a baking sheet and dried at 140-150 ° C until the water is completely removed. 230.0-245.0 g of a phthalic acid dicapium salt suitable for repeated use is obtained. With repeated use of such a reducing di-potassium salt, there was no deterioration in the quality and decrease in the yield of phthalylene acetic acid. Thus, the proposed method allows the use of phthalic acid production wastes. In addition, the initial salt of phthalic acid is easily recovered from the aqueous solution obtained after filtration of phthalate denucetic acid. The yield of the target product per phthalic anhydride is increased up to 90-95%, and carrying out the process at a low temperature eliminates the use of methanol for the purification of phthalidene 1 cc acid. The invention method for producing phthalideneacetic acid by condensation of phthalic anhydride with acetic anhydride by heating in the presence of an alkali metal salt of an organic acid, characterized in that, in order to increase the yield and simplify the process, an alkaline metal salt of an organic acid is used when the phthalic acid salt is used and 115-125 С, Sources of information taken into account during the examination: 1. G. Tirzig and others. About obtaining indandion-1, 3 and bindon, Izv, Academy of Sciences of the Latvian SSR, Chem series , № 1, 97-101. - 2. Fizer, L, Fizer M. Organic Chemistry, Chemistry, M., 1970, p. 71,