SU15335A1 - The method of purification of acetic-sodium salt, obtained as a by-product in the production of para-nitroaniline - Google Patents

Description

Usually, in the production of paranitroanine .gin (CgH, NOj. ISTHj), narantroacetanidine (ISTOj. NHOCCHj) is washed with sodium hydroxide solution. The resulting laranitroaniline settles to the bottom, while the solution,% drained from the precipitate, contains mainly CHj.COOisTa, an excess of NaOH and some para-and ortho-nitroaniline. This solution is evaporated to 31-32 ° Be and the residue crystallizes.

The crystals of the acetic sodium salt of sodium salt obtained in this way are usually heavily contaminated with various resins and o-and p-pitrophenolites, and therefore it is difficult to apply them in this form.

The proposed method is intended to use this valuable byproduct of the production of paranitroaniline by purifying it from accompanying impurities. To achieve this goal, 1500 kg of the above Kristau acetic sodium salt mixture mixed with resins and 0- and p-nitrophenolates are dissolved in a wooden tank with an equal amount of water in the mixer, while stirring and heating with hot steam to 60 ° C. After the dissolution is finished, the action of the stirrer and the steam is stopped and the pacTBQp is settled while it is simultaneously cooled to 28 ° C. Due to weak

solubility of nitrophenols in cold water, most of them fall out in the form of long silky needles, and along with them resin also falls out. The solution is filtered from the precipitates and to it is added up to 10 ° / o from the weight of the initially taken amount of bleach crystals mixed with water in the form of a dough in a 1: 1 ratio. The resulting mixture is stirred in a vat with stirrers for 2-3 hours; then, without stopping the action of the agitators, the mixture is heated with steam to 80-90 ° C, after which the liquids are allowed to stand for at least 24 hours. The spaced solution is carefully decanted from the bright yellow precipitate of Ca (OH); and CaCOj; the clear, slightly yellowish solution is poured back into the stirred tank, acetic acid is added to the acidic reaction and the mixture is again treated with 2, L ° 1 bleach in a pasty form, as described above, while mixing chlorine will not decline.

Further, with constant stirring, the mixture is introduced into a clearly alkaline reaction and the formation of a precipitate of CaCOj is stopped. The solution is defended, decanted and transferred to the uparku in a cast iron pot ,. equipped with a dull steam coil. The clear, colorless solution is evaporated to 3.8 ° C at 15 ° C and left to stand for 3–4 hours in a hot state, whereupon the precipitation ends

formed

CaCOj H drops out NaCl, from OaGl

2 contained in bleach and soda.

Then, the solution is lowered into the molds. The formation of crystals is, depending on t ° ambient air, from 3 to 6 days. The crystals are removed and sucked off from the mother liquor, which is added to the next step for new processing.

The evaporation of the obtained colorless solution in the β-crystallizer does not represent any particular difficulties, but if, after descending into the molds, the evaporated solution darkens slightly, then the mushroom 20-25 l of residual bleach produces a final and permanent bleaching of the evaporated solution.

The yield of the acetic sodium salt according to the method described above, according to the authors, reaches up to / Theory, and the analyzes they produced gave the following results:

CH, 000 Ms. -96.5 ° / o

Water hygroscopic - ,,

. .. -. ZhaS1-2.

White colour.

The subject of the patent.

The method of purification of the acetic sodium salt obtained as a by-product in the production of daranitroaniline, characterized in that the crystals of the salt to be purified are dissolved in hot water, the settled and cooled solution is filtered, then the alkaline filtrate is treated with a solution of chlorine lime, added with acetic acid before acidic reaction, they are again treated with bleach, all calcium is precipitated with soda and the decantrated solution is evaporated.