CS197187B1 - Method of preparing metanilic acid and salts of the same - Google Patents

Description

The present invention relates to the preparation of metanilic acid or a salt thereof, such as sodium, ammonium, calcium and the like, and is essentially a catalytic reduction of m-nitrobenzenesulfoic acid or methacrylic acid. the corresponding salts, prepared from nitrobenzene, with hydrogen.

Until now, this amino compound has been prepared in a conventional manner by reducing the corresponding mismatched components with iron dis Bachampa. The production process can be expressed by the following scheme:

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This prior art process, besides requiring a considerable amount of auxiliary raw materials mainly Fe, MCI, NaOH etc., of energy and labor, provides a large amount of solid and liquid waste. Although the disposal of these wastes does not place too much of an economic burden on the process, these wastes pose great environmental problems for the amino substance content.

According to the present invention, methanilic acid and methanilic acid are prepared. its salts of the general formula 1.

where K denotes H, NH4, Na or Ca by reducing the corresponding nitro compound with hydrogen in an aqueous medium, optionally in organic polar solvents, in the presence of precious metal nickel or hydrogenation catalysts, whereupon the product is isolated in solution or Methanil, optionally in the form of a salt, isolates the kyeelenin of the aqueous solution on the basis of different solubility depending on the temperature or evaporation of the solvent used, while the mother liquors and solvents are returned to the process, evaporated water to waste *

The catalytic reduction is carried out in a batch process or in a continuous flow reactor.

For example, water or organic solvent can be infused into the hydrogenation autoclave · nitro compound or direct nitro compound solution, optionally adding acidic (sulfuric acid, hydrochloric acid) or alkaline reaction (hydroxides), adding catalyst, allowing hydrogen and hydrogenation is performed. However, the order of mixing components changes decisively and can be introduced into the reactor in any order. Reaction conditions such as heat, pressure, ingredient concentration, molar ratio between nitrile and additives affecting the pH of the mixture and the amount of catalyst naked can vary widely. Maximum working temperature is limited by 2JO * C, because at higher temperatures decomposition of nitro compounds or amino compounds occurs.

The choice of the concontraco nitro compound is largely influenced by the mixing possibilities of the system and the solubility of the individual substances, eg when preparing methanilic acid in an acidic environment, it chooses a greater degree of dilution, while up to 40-6% solution or euepension can be used.

The continuous process of the present invention can be carried out in one of the conventional flow hydroassembly reactors, for example, by spraying euepension with nitro compounds and catalyst and hydrogen into the reaction space.

Fingers of the previous method of cutting show a paatup increase of proceau yield, increase of product quality, significant reduction of waste, higher hygiene and safety of work etc.

According to the invention, aa isolates the reaction from the reaction or the following:

· Isolation in the form of the aethanilic acid salt after filtering off the catalyst, according to the prior art;

b) isolation of the solid non-flammable acid in agreement and the present poatupen (acidic acid) from its salt / but the difference is that the inert caustic liquors after the isolation are not discharged into the waste water but recirculated back to the process;

c) isolating the non-tannilic acid base from the reaction mixture on the basis of different temperature e, the inert liquor ae returns to de preeeau;

d) in the case where organic polar solvents are used, and e. ,

Example 1

550.0 g of 25.15% ha are introduced into a stirred autoclave. solution of sodium m-nitrobenzanesulfonate and 20.0 g of water and rinse with 1.06 g of the palladium catalyst. The autoclave is purged with nitrogen and hydrogen. After heating the autoclave at 90.0 ° C, the hydrogen is impregnated to a pressure of 0.7 MPa and the mixing is started. The hydrogenation is 130 nin.

After hydrogenation in the pressure filter, the catalyst and the filtrate and others are passed into a cooled flask. 550.0 g of a solution of netanilate are obtained with a concentration of at least one

21.47% wt. The catalyst may be recirculated or regenerated;

Example 2

500.0 g of water are introduced from a stirred autoclave preheated to 50 DEG C. and 200.0 g of water are flushed with 50.0 g of ammonium m-nitrobenzenesulfonate (99.46% ϊοβ. »/ N 2.0 g of Sa-Ni catalyst). 50% ha. aqueous paste /. * After being heated to 90 ° C, flushing with duct and hydrogen, the hydrogen purges to 10.0 MPa and starts stirring. The hydrogenation time is 90 min.

After hydrogenation and separation of the catalyst, 744.0 g of an ammonium methenilate solution of 4.51 * ha are obtained. The catalyst was used for the next batch.

Example 3

650.0 g of water, 30.0 g of calcium m-nitrobenzenesulfonate (99.89% w / w) and 1.5 g of Xa-Ni catalyst (50% water vapor) are charged with a heated stirred autoclave (90 * 0).

After hydrogen hydrogenation to 10.0 MPa ae stirring was started. The hydrogenation time is 255 min.

AND

After separation of the catalyst, 663.0 g of a calcium methanilate solution having a concentration of 3.76% by weight are obtained. The catalyst can be recirculated or disposed of ·

AND

AND

Example 4

650.0 g of water and 50.0 g of nitrobenzene eulfonation paste with a content of 80.79% by weight are introduced into a heated stirred autoclave (90 DEG C.). m * nitrobenzene sulfoacids, 5.05 wt. sulfuric acid β 14: 16% wt., water. After the addition of 0.5 g of the palladium catalyst, the nitrogen purge and the autoclave were purged with hydrogen to a pressure of 0.5 MPa. The hydrogenation time is 80 min.

After separation of the catalyst and cooling, the precipitated methanilic acid was filtered off and dried at 105 ° C. A total of 20.1 g of dry methanilic acid was obtained. The mother liquors can be recirculated and used instead of water.

Example 5

To the autoclave 360.0 g ae submit ethanol / 96% / \ _t 100.0 g of sodium m-nitrobenzenaulfonanu / 99.3 56 mass./ paladiováho and 1.0 g catalyst. After purging with nitrogen, hydrogen and heating to 90 ®G ae hydrogen impregnated to a pressure of 0.7 MPa and start stirring. The hydrogenation time is 200 min.

Claims (1)

A process for the preparation of methanilic acid and a salt thereof having the general formula I, wherein R is R, NH4, Na or Ca, characterized in that the corresponding nitro compound is reduced by hydrogen in water, optionally organic polar solvents in the presence of hydrotreating catalysts. precious metal base, whereupon the product is isolated in solution or the methanilic acid or salt, respectively, is isolated by acidifying the aqueous solution on the basis of different temperature-solubility or by evaporating the solvent used, returning the mother liquors and solvent back to the process , evaporated water to waste.