SU906992A1 - Process for preparing sodium dichloroisocyanurate - Google Patents

Description

I

This invention relates to a process for the preparation of dichloroisocyanuric acid sodium salt, which is a source of active chlorine and is used in the manufacture of bleaching blends, degassing agents, disinfectants, compositions, and the like.

The known method of luchrochenn sodium dichloroisocyanurate by chlorination of cyanuric acid in an aqueous-alkaline medium with gaseous chlorine 1.

The disadvantages of this method are low yields and insufficient stability of the product as a result of its contamination with sodium chloride, which is formed as a result of the reaction.

There is also known a method for producing sodium dichloroisocyanurate by reacting trichloro cyanuric acid, Fshnuric acid and caustic soda in an aqueous medium. The heat of formation of sodium dichloroisethianurate in this case is 13.6 kcal / mol, the process is carried out in a large excess of water (more than 50%) with cooling 12.

The closest to the proposed technical essence is the method of obtaining sodium hydroxyethyl carbonate by reacting trichloride acid with trisodium cyanurate, taken in a 2: 1 ratio, in an aqueous medium.

The reaction of trichlorofluoric acid with trisodium cyanurate is carried out in a large excess of water (50-90%), i.e. in solution, at O-60 C to pH 5-8.5. In this case, a neutralization heat of about 4 kcal / mol is released. Trisodium cyanurate is a mixture of diatriane cyanurate and caustic soda in a molar ratio of 1: 1 {3.

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A disadvantage of the known methods is that the sodium dichloroisocyanurate that is formed crystallizes from a larger excess of water, while a large amount of product remains in the mother liquor (dissolving sodium dichloroisone anurate in water at 20 ° C 25%).

Claims (4)

Isolation of the product from the mother liquor is a laborious and energy-intensive propedera requiring MHcirocryneiNaroH vacuum evaporation, crisplilaisia and phytraxia. The greatest difficulty is in the occurrence of wet sodium dichloro- nyanurate - it is heated at 50-55 ° C, a true solution is formed, and an intensive decomposition of the product begins, with os formation of trichloride nitrogen and chlorine dioxide. Drying a product with such properties is very difficult and requires special techniques 4. The purpose of the invention is to simplify the process. The goal is achieved by the method of obtaining sodium dichloro cyanuric acid by reacting trichloroisocyanuric acid with disodium aniurate and caustic soda at a molar ratio of reagents of 2: 1: 1 and a pH of the reaction mass of 6-7, in the presence of water at 45-85 ° C and total humidity of the reaction mass of 14 , 5-20%. The interaction of the starting products is carried out according to the scheme CjMjOmoNcl), 4KaO "- --.- CjHjCefj DMQ HQ o-va The heat of the reaction including the heat of hydration of sodium dichloroisocyanurate is about 5 kcal / mole. When carrying out the process in the presence of a limited amount of water, i.e. In the pasty state of the reaction mass, the stability of sodium dichloroisocyanurate is gradually increased. With a total moisture content of about 15%, sodium dichloride cyanurate does not diffuse and does not decompose when heated to 85 °, and with a moisture content of 20% it is possible to heat the product without decomposing to 65-70 ° C. If the moisture content of the reaction mass is pre-Bubuac-T is 20%, unstable crystals form. When moisture content is reduced to 14% and below, the neutralization reaction does not go to the end. The possibility of carrying out the process of obtaining sodium dichloroisocyanurate in a paste is determined by the fact that the reaction can be carried out under adiabatic conditions, i.e. without heat dissipation through the wall of the apparatus. Example 1. In a 100 l horizontal reactor equipped with two Z-shaped agitators, 15.2 l of a 44% sodium hydroxide solution (10 kg of 100% NaOH) is charged and 16.5 kg of cyanuric acid are added with stirring content of the main substance is 98%. The temperature of the reaction mass rises due to self-heating up to 55 ° C. After holding the reaction mixture under stirring I for 0.5 h, the intermediate product is fed into the jacket of the apparatus and nysushin.chut. The resulting dinagriaciaurt is cooled to 0 g. 7.8 l of a 44% solution of caustic soda (5 kg of 100% NaOH) and 12.5 l of water (based on the total moisture content of the reaction mass 20%) are charged to the same reactor stir the mixture for 10 minutes, after which 59 kg of trichloro cyanuric acid with a content of the main substance of 89.9% (58.1 kg based on 100%) are gradually added. The temperature of the reaction mass rises due to self-heating up to 68 ° C. After all the trichloro cyanuric acid is added, the reaction mass is maintained at a displacement for 30 minutes. The product is dried under vacuum at AIA. Received 94.5 kg of sodium dichloroisocyanurate dihydrate with an active chlorine content of 52.95% and a total moisture content of 14.03%. The yield is 98.5%. Example 2. The process is carried out under conditions analogous to example 1, but upon receipt of sodium dichloroisociaiurate, 7 liters of water are added (based on the moisture content of the reaction mass of 15%). The temperature of the reaction mass due to self-heating is adjusted to 81 s. The process is then continued as described in Example 1. 94.2 kg of sodium dichloroisocyanurate dihydrate were obtained with an active chlorine content of 53.1% and a total moisture content of 13.85%. The yield is 98.3%. Example 3. -Disodium disodium iurate as described in example 1 is obtained, the disodium cyanurate is cooled to 0 ° C by supplying a cooling agent to the jacket of the apparatus and the process proceeds as in example 1. The temperature of the reaction mass rises to 47 ° C. , 6 kg of dihydrate are sodium dihydrogen isocyanurate with a moisture content of 14.02%. The yield is 98.2%. Example 4. Disodium cyanurate, prepared as indicated in Example 1, is mixed with solid caustic soda in a weight ratio of 4.35: 1. B, the continuous synthesis reactor, which is a horizontal apparatus with a length of 2.0 m and two rowing agitators continuously, comes from a trichlorocyanuric acid drum vacuum filter with a humidity of 6-8%. In the same reactor, a mixture of disodium cyanurate and caustic soda is metered continuously, adjusting the flow rate so that the pH of the reaction mass at the outlet lies in the range of 6.0-7.5. Water is fed into the reactor in such a way that the wet part of the reaction mass is 18%. The temperature of the reaction, the mass in the apparatus at the expense of oamorayugrov half the temperature at 68 ° C. The residence time of the reaction mass in the apparatus is 40 minutes. The moist product is dried in a molten dryer with air with an initial temperature of 75 ° C and a final temperature .. Sodium dihydrocyanurate dihydral was obtained with a chlorine content of 52.2% and a total moisture content of 13.9%. EXAMPLE 5 The process is carried out as indicated in Example 4, but the water supply is increased so that the moisture of the reaction mass is 22%. The product in the dryer melts, settles on the walls of the drying chamber and fills the dryer-15 ku. The process is stopped at the “source of the dryer. The proposed method is suitable for the production of sodium dichloroisocyanurate both in periodic and non-continuous methods. The invention The method of obtaining sodium salt of dichloro-isocyanuric acid by reacting 20 2. 6 trichloroisocyanuric acid with disodium cyanide and caustic soda nun the molar ratio of reagents 2: 1: 1 and the pH of the reaction mass is 6.0-7.5 in the presence of water when heated with the release of the target product, characterized in that, in order to simplify the process, the process is carried out at a total moisture content of 14.520% and 45-85 C. Sources of information (aces taken into account in the examination 1. US Patent N 3035056, cl 260-248, Publication 1962 2. Patent of France M 2069469, cl. C 07 d 55/49, published 1971. 3. US patent N 3035057, cl. 260-248, publ. 1962 (prototype). . 4. The patent of Germany N «2053983, cl. 12 p 10/05, published 1972.