CS250571B1 - Method of substituted arylguanamines preparation - Google Patents

Description

The invention relates to a process for the preparation of substituted arylguanamines.

The preparation of substituted arylguanamines is described, for example, in DAS 1 019 310 or in the patent V. Brit. 685,890, where it is associated with carrying out the reaction in boiling ethoxyethanol. The actual product separation usually requires dilution of the reaction mixture with water, thereby increasing the demand for solvent recovery.

It has now been found that substituted arylguanamines of the general formula

where

R1 = H, Cl NH2, OCH3, are prepared very advantageously according to the invention.

The process for the preparation of substituted arylguanamines by reaction of the corresponding aromatic dinitriles with dicyandiamide under the catalysis with a basic catalyst is according to the invention in that the reaction is carried out in isobutanol and the basic catalyst is dosed as isobutanol solution in connection with the exothermic color of the reaction.

The cyclization itself is carried out by suspending the dicyandiamide and the corresponding eryldinitrile at room temperature in a portion of isobutanol or in a recycled mother filtrate, and then heating the mixture to 90 [deg.] C. and charging the isobutanol catalyst solution. The reaction proceeds slowly at first, and then, with increasing temperature, very vigorously and depending on the nature of the nitrile. After completion of the catalyst feed, the reaction mixture is kept under reflux for 3-4 hours. It is then cooled to 20-30 ° C and filtered on a pressure suction filter. The isobutanol filtrate obtained is used as part of the isobutanol charge for the following operation. The feed for the subsequent operations is then always made up of a constant amount of dicyandiamide and aryldinitrile. Only isobutanol and catalyst losses are added.

The filter cake was slurried with suction and washed 3 times with boiling water (around 98 ^Q C), and finally blown out with pressurized nitrogen. A further fraction of the crude arylguanamines is isolated from the aqueous filtrates after cooling by filtration

571

250 is added to the product after washing with a minimum amount of boiling water. The product is dried in a vacuum oven at 110-120 ° C. After the series of arylguanamine preparations has been completed, the last mother filtrate in a stirred separator is washed with 30-40% sodium hydroxide solution, the organic layer is separated and isobutanol is recovered from it by rectification at atmospheric pressure.

The reaction proceeds quantitatively in almost all cases, the potential losses being due only to the different water solubility of the individual arylguanamines during the washing.

The preparation of the above-mentioned substituted arylguanamines with recycle of the mother isobutanol filtrate can be carried out in conventional batch reactors equipped with a duplicator and a pressurized nitrogen discharge purge. Filtration and washing of the product on a suction cup with boiling water usually does not cause problems.

The example below illustrates an embodiment of the invention.

Example

0.23413 mol tereftalodinitrilu optionally substituted tereftalodinitrilu and 0.51346 mole of dicyandiamide was suspended under stirring in 550 ml of isobutanol and heated to 90 C. Then ^d within 60 minutes indicating portions isobutanolového 50 ml KOH solution (0.04124 mole) . During the catalyst addition, the reaction mixture was stirred vigorously as the product immediately precipitated out in solid form and thickened. After the addition was complete, the reaction mixture was kept under reflux for 4 hours, then cooled to 50 ° C and the crude product was separated by suction filtration. The filter cake on the suction was washed with 100 ml of boiling water and after cooling the filtrate, the isobutanol layer was separated in a separator, which was fed for regeneration. The washed filter cake is suspended in 300 ml of boiling water and filtered again. Cleaning of the product is completed by washing the cake twice with 200 ml of boiling water each time. The yield of terephthaloguanamine without isolation of the product from the wash water and without recirculation of the mother filtrate was 50 g, i.e. about 72% of theory, for the technical terephthalodinitrile used.

Claims (1)

A process for the preparation of substituted arylguanamines of formula INVENTION where R1 denotes H, Cl, NH2, OCH3 by reacting the corresponding aromatic dinitriles with dicyandiamide under catalysis with a basic catalyst, characterized in that the reaction is carried out in an isobutanol medium and the basic catalyst is dosed in the form of an isobutanol solution in connection with the exothermic color of the reaction.