CS201486B1 - Method of preparing 5-chlor-2-methyl-1,4-phenylene diamine by reduction of 5-chlor-2-methyl-4-nitroaniline - Google Patents

Description

The processes described above to prepare the compound used concentrations of nitroaniline at which the diamine remained in solution after Béchamp reduction and was easily separated from the iron sludge by filtration. Due to the low solubility of the diamine, the volumetric capacity of the reducer was very low in water; = 1.97 kg. m ^-3 . li ^-1 .

It has now been found that the Béchamp reduction can be carried out in a suspension with a much higher concentration of the starting nitro compound to produce 5-chloro-2-methyl-1,4-phenylenediamine by reducing the 5-chloro-2-methyl-4-nitroaniline of the present invention. characterized in that the reduction is carried out in suspension at a concentration of 2 to 15% of 5-chloro-2-methyl-4-nitroaniline, based on the total volume of the mixture, the diamine formed is separated from the reducing sludge by hot aqueous ethanol; the filtrate is cooled and the crystallized diamine is filtered off, the ethanol is distilled off from the mother liquor and the distillation residue is used in the subsequent reduction after making up to the original volume with water.

The resulting diamine remains in suspension together with the iron sludge after the reduction, but this is not a problem, since after the addition of ethanol to a total concentration of about 30% by volume and brief boiling under the reflux condenser directly in the reducer, the diamine solution, which is neutralized with Lovinite, decolorizes with carboraffin, the sludges are separated by filtration in the hot state, and a diamine of considerable purity crystallizes in an aqueous ethanol solution. The diamine is separated and the resulting mother liquors are then freed from ethanol by distillation, which is re-used for further treatment after rectification. The high diamine distillation residue is returned to the next batch, where the volume is adjusted to its original value with water, followed by another reduction cycle.

Compared with the prior art reduction processes using a lower concentration of the starting material, the process according to the invention allows to increase the volumetric capacity of the reducer V _; from an average value of 1.97 kg. m ~ ³ . h ^-1 to 6.45 kg. iri ^-3 . h ^_1 . In addition, a complex theoretical recirculation of the mother liquors yields a maximum theoretical yield of 97% over 93% of the prior art processes.

The examples below illustrate embodiments of the invention.

The Lovinite used is a waste magnesium oxide with a content of about 88% by weight. magnesium oxide, contaminated with silicon oxides?

Iron, manganese and calcium.

Example

A 2.5 L flask equipped with a thermometer, stirrer and reflux condenser was charged with 531.7 g water, 0.375 g-Slovasol 0, 97.5 g Fe-sawdust and 9 g concentrated HCl. After half an hour of boiling etching, a gradual dosing of the nitroderivative paste was started with appropriate Fe ²⁺ tests and the reduction was terminated. Dosing was discontinued. after 2 hours. A total of 307.3 g of paste was dosed. After stirring for half an hour, the temperature was lowered to 80 ° C and 324.3 g of toluene denatured ethanol was added and stirred for another half hour while boiling the mixture (84 ° C), then 3.75 g of Lovinite were added. After about ten minutes, when the Fe ²⁺ test was already negative, 4.125 g carborafine and 0.975 g Na 2 SO 3 were added. The reaction mixture was filtered on a folding filter in a heated funnel. The reducing sludge was washed with 37.5 g of hot 30% ethanol, the filtrate of 1022 g cooled to 26 ° C and the crystallized diamine separated by suction filtration. After washing with 75 g of water and suction, it was dried in a vacuum oven at 60 ° C to constant weight. The filtrate after separation of the diamines was subjected to batch distillation using a 5 theoretical tray column (0 27 mm column, 450 mm length, Crutch Saddle). From the seeded 882 g of mother liquors, 407 g of 53% ethyl alcohol were distilled off. The distillation residue was used in the following experiment instead of the presumed water, and only made up to a weight of 531.7 g with water.

The table below illustrates the results of the embodiments of the invention.

Example no. Recycle Water _g Mother liquor after distillation. et-OH O Product Mother liquor before decay. et-OH _g Teoret. yield % G diaz. anal. of diamines _O y _g 2 0 531.7 - 63.8 98.8 884 86.0 3 0 531.7 - 64.7 99.0 920. 87.4 4 0 531.7 - 63.5 100.5 924 88.2 5 1 64.7 467 69.7 98.9 908 '94.1 6 2 146.7 385 73.5 97.5 918 96.8 7 3 84.7 . 447 72.1 99.6 947 97.0 8 4 54.7. 477 72.2 100.9 895 97.5 9 5 100.7 431 70.0 100,8 ' 934 94.5 10 6 145.7 386 73.4 99.0 910 98.1 11 7 94.7 437 70.4 99.7 952 94.8 12 8 111.7 420 , 72.4 92.8 935 95.8 13 9 91.7 440 73.9 98.7 941 98.5 '14 10 87.7 444 74.5 97.8 896 98.4

SUBJECT

Claims (1)

SUBJECT Process for the preparation of 5-chloro-2-methyl-1,4-phenylenediamine by reduction of 5-chloro-2-methyl-4-nitroanilines, characterized in that the reduction is carried out in suspension at a concentration of 2 to 15% of 5-chloro-2-methyl-4-nitroanilines. 2-methyl-4-nitroaniline, based on the total volume of the mixture, the diamine formed is separated from the reducing sludge by hot aqueous The filtrate is cooled and the crystalline diamine is filtered off, the ethanol is distilled off from the mother liquor and the distillation residue is used in the subsequent reduction to the original volume with water. ./ Jihočeské tiskárny, n. P., Operation 6 Jindř. Hradec Price: 2,40 Kčs