SK1832000A3 - Method for the treatment of inorganic salts resulting from the production of pyran - Google Patents

Abstract

Method for the treatment of inorganic salts resulting from t he production of pyran, i. e. mixtures K2CO3, KHCO3, KCl, KBr, is realised by a thermal conversion of KHCO3 to K2CO3 in the aqueou s medium and by isolation of ethanol and pyran absorbed, and by d istillation of the aqueous steam in the CO2 under the atmospheric pressure. The mixture of KCl and KBr are isolated from the solut ion of K2CO3. The aqueous solution K2CO3 is purified sorptively b y the active coal and K2CO3 in the solid form is obtained in the spraying kiln with desolventizer.

Description

Technical field

The invention relates to the processing of by-products resulting from the production of one of the basic intermediates in the synthesis of pentoxifylline-2-methyl-1-3-carbethoxy-5,6-dihydropyran (in another pyran).

Description of the state of the art

In the first stage of the synthesis of pentoxifylline, pyran is produced by reacting 1-bromo-3-chloropropane and ethyl acetate in anhydrous ethanol, in the presence of anhydrous potassium carbonate according to CS Auto Certificate No. 248 932. After carrying out the reaction, the alcoholic pyran solution is isolated by centrifugation. By-product of the reaction is a mixture of inorganic salts: potassium bromide (KBR), potassium chloride (KCL), potassium bicarbonate (KHCO ₃ ), and excess potassium carbonate (K ₂ CO ₃ ). This mixture is soaked with residual ethanol and part of the product itself - pyran.

In the prior art, the treatment of the inorganic salt mixture of pyran production is not disclosed.

SUMMARY OF THE INVENTION

The process according to the invention solves a process for treating inorganic salts of pyran production, ie K2CO3, KHCO3, KCl, KBr and soaked ethyl alcohol and pyran, by thermally converting KHCO3 to K2CO3 at atmospheric pressure and temperatures of 70 to 120 ° C while releasing carbon dioxide (CO ₂ ) and isolating the pyran, ethanol, KCl and KBr, aqueous K 2 CO 3 solution, respectively. K2CO3 in solid form.

The inorganic salts of pyran production are metered into the present water, from this reaction mixture the ethyl alcohol fraction is distilled off at atmospheric pressure at 78 to 100 ° C, the pyran from the mixture is distilled with water vapor and a CO ₂ stream at 100 to 120 ° C, whereby CO2 is generated by thermal decomposition of KHCO3. The distillation was terminated when the aqueous solution reached 53% K 2 CO 3, leaving the residual thermally undecomposed KHCO 3 to react with the aqueous KOH solution to K 2 CO 3. The mixture of KCl and KBr is obtained by centrifugation, the aqueous solution is sorbent-purified with activated carbon. K2CO3 in solid form is obtained in a spray dryer with desolventizer at an inlet temperature of 150 ° C and at a pressure of 98 kPa in the desolventizer.

The advantage of this process of waste salt treatment is to obtain pyran in pure form and significant economization in the first stage of pentoxifylline synthesis - in the production of pyran.

In the following, the process is illustrated by way of example without limiting it.

DETAILED DESCRIPTION OF THE INVENTION

The subject inorganic salts from the production of pyran, in an amount of 5000 kg, are metered into 10,000 L of enameled rector, where 25001 water is presented. The contents of the reactor were stirred for two hours at ambient temperature (20-25 ° C), and the resulting slurry was passed through two 3500 L enamelled reactors equipped with a column and a reflux condenser by dividing them into two equal portions. The slurries in the reactors were steam heated to distill off the ethyl alcohol fraction at a boiling point of 78-100 ° C at the top of the column at atmospheric pressure, developing vigorously carbon dioxide evolution in a total amount of 380 kg. This fraction in an amount of 1100 L contains ethanol at a concentration of 88-92%.

Once the boiling point of water has been reached, distillation of the water and the pyran is continued, with a 90% pyran at 60 kg being withdrawn through the flow divider.

The distillation is terminated when the aqueous solution reaches 53% potassium carbonate content, while thermally undegraded KHCO3 in an amount of 100 kg is reacted with 140 kg of a 40% aqueous KOH solution to K2CO3.

A 1: 2 mixture of KCL and KBr at 1600 kg is obtained by centrifugation.

The aqueous potassium carbonate solution was purified by sorption with 20 kg of activated carbon. 4000 kg of a 53% potassium carbonate solution are obtained

1800 kg of K 2 CO 3 with a 58% potassium oxide (K 2 O) content are obtained from an aqueous potassium carbonate solution in a desolventizer spray dryer at an inlet temperature of 150 ° C and a pressure of 98 Kpa in a desolventizer.

Industrial wuseability

The invention is useful in the industrial manufacture of the substance pentoxifylline in the first step of the synthesis of pentoxifylline, i. in the manufacture of pyran for the treatment of inorganic salts resulting from the manufacture of pyran.

Claims (1)

PATENT CLAIMS Process for the treatment of inorganic salts from pyran production, characterized in that the inorganic salts from pyran production, ie K 2 CO 3, KHCO 3, KCl, KBr and the soaked ethyl alcohol and pyran are treated by thermal conversion of KHCO3 to K2CO3 at atmospheric pressure and temperatures from 70 up to 120 ° C with simultaneous release of carbon dioxide and isolation of pyran, ethyl alcohol, KCl and KBr, aqueous K 2 CO 3 solution, respectively. K2CO3 in solid form. _e 2. The treatment of the inorganic salts from the production pyran according to claim 1, characterized in that the inorganic salt is present in the dosed water from the reaction mixture was distilled off at atmospheric pressure etylakoholová fraction at 78 to 100 C, with vapor stream and CO2 distills pyran at temperatures from 100 to 120 ° C, which is generated by the thermal conversion of KHCO3 to K2CO3, and the distillation is terminated when the aqueous solution reaches 53% K2CO3 content, leaving the residual thermally undisturbed KHCO3 to react with aqueous KOH to K2CO3 , the mixture of KCl and KBr is obtained by centrifugation and the aqueous solution is sorbent-treated with activated charcoal, and the solid form of K 2 CO 3 is obtained in a spray dryer with a desolventizer at an inlet temperature of 150 ° C and a pressure of 98 kPa in the desolventizer.