SU891646A1 - Method of preparing methacrylamide sulphate - Google Patents

Description

(54) METHOD FOR OBTAINING METACRYLAMIDE SULFATE

I

The invention relates to the improvement of methods for producing methacrylamide sulphate (CAMP) used in the production of methacry monomers.

Methacrylamide sulphate, which is a solution of methacrylamde (AMC) in sulfuric acid, is obtained by reacting acetone cyanohydrin (ACH): with sulfuric acid or by hydration of methacryponitrile in a medium of sulfuric acid.

A known method for the preparation of methacrylamide sulfate by the interaction of acetone cyanohydride and 100 hydrochloric acid at 70-90 ° C results in the formation of acidic sulfate a-hydroxyisobutyramide (CEA). In the second stage, when heated to 125-135 ° C, the SER turns into SAMK C.

However, according to this method, about 10% of ACG is converted into side products, the main part of which is sulfoproducts.

There is also known a method for the preparation of methacrylamide sulfate, according to which acetone cyangtsdrin is converted with pyroboric acid to boric ester, which is further

by treatment with 100% sulfuric acid and with water, they are converted into the desired product 2.

The disadvantage of this method is that when it is carried out, the problem of boric acid release arises. Since the problem of boric acid regeneration is not resolved, this method has not found hilarious use. In addition, according to this method, with the further polymerization of methacrylic acid,

10 Methyl boric acid ester, which causes not only an undesirable loss of boric acid, but also due to a slight flammability, volatility and high toxicity, is a serious danger if this method is implemented.

In addition, there is a known method of producing methacrylamnd sulfate by heating a mixture of ACG with 10% sulfuric acid at 120-140 ° C in the presence of alkali metal alkali metal

Claims (4)

20 and phosphoric acid. The ratio of Hj 804: salt is 100: 0.5 to 10 by weight. The yield of methacrylamide sulphate by this method is about 95% (3. 3 The disadvantage of this method is the additional costs for the use and regeneration of additives. The closest to the proposed technical essence and the achieved result is the method of methacrylamide sulphate, according to which sulfuric acid and n-hexane is loaded into the reactor and acetone cyanohydrin is added at a temperature of 68-72 ° C for 20 min. Then the reaction mixture is heated to 120-140 ° C (at the same time n-hexane is removed from the reaction mass) and held at The temperature is 30 minutes For the synthesis, sulfuric acid is used with a final not less than 99% or oleum .. The molar ratio of the components of ACG: n-hexane is 1: 1.4: 0, the yield of methacrylate sulfate is 95% (bromination) 4. Despite Although the known method provides some increase in yield, it has significant drawbacks: the methacrylamide sulfate obtained contains 5-7% sulphated products, moreover, during the synthesis of methacrylic acid and methyl methacrylate from CAMA, sulfonated products are converted into insoluble gums which These cause the clogging of reactors and pipelines, because of which technological systems often stop. Sulfonated products and resins also complicate the process of processing waste sulfuric acid into ammonium sulfate. The purpose of the invention is to increase the yield of the target product and simplify its technology. The goal is achieved by the method of producing methacrylamide sulfate by reacting acetocyanohydrin with 90-98% sulfuric acid at 15-60 ° C, after which the resulting reaction mass is treated with sulfuric anhydride or oleum with an adequate amount of sulfuric anhydride to the water of the reaction mass, then subjected to dehydration at 120-140 ° C. With a decrease in the concentration of sulfuric acid (less than 90%), it is necessary to increase the consumption of F3, which leads to an increase in the final ratio of sulfuric acid (100%) by more than 1: 2, which increases the aggressiveness of the medium and makes the method not economical. The use of sulfuric acid above 98% concentration leads to an increase in the content of sulfonated products. Example 1. To 108.8 g (1 mol H2SO2 and 0.6 mol water) of an aqueous solution of sulfuric acid, at 15 ° C and stirring, 85 g (I mol) of ACG are poured over 15 minutes. Next to the reaction mixture is poured with intensive cooling and stirring at the same temperature 48 g (0.6 mol) of sulfuric anhydride. The resulting reaction mass (ratio of ACG: H28O41: 1, 6) is heated to 130 ° C and maintained at this temperature for 40 minutes. The output of methacrylamide sulfate (CAMK) is 98.1%. Determination of sulfonated by-products. 100 ml of ice water is poured into 100 g of CAMA and neutralized with ammonia. Water is distilled in a stream of air. The residue obtained is treated three times with 200 ml of diethyl ether, then three times with 150 ml of hot methanol. The methanol solution is evaporated in a stream of air to 30 ml. From the methanolic solution, by adding 150 ml of ether, 0.72 g of the sulfonated ammonium salt of the product was extracted. Analysis of the ammonium salt gives the following results.%, Ammonium nitrogen 8, total nitrogen 11.6, carbon. 22.33, hydrogen 5.2, sulfur 20.62. The content of sulfonated product in CANdK is 0.98%. Example 2. To 160 g (1.6 mol H2SO4 and 0.18 mol HjO) of an aqueous solution of sulfuric acid with a 98% concentrated solution, with g, 85 g (1 mol) of ADH are added with stirring for 15 minutes. Next, 16 g (0.18 mol) of sulfuric anhydride are added to the reaction mixture at the same temperature. The resulting reaction mass (ACG: H2SO4 ratio 1: 1.8) is heated to 130 ° C and held at this temperature for 40 minutes. CAMK yield 97.2%. The content of sulfate derivatives is 1.5%. Example 3. To 113.4 g (1.1 mol HjSO and 0.3 mol HjO) of an aqueous solution of sulfuric acid of 95% concentration, 85 g (1 mol) are gradually added with stirring. SCG. Displacement temperature 2СГС, mixing time 20 min. To the resulting reaction mass was added 36.92 g of 659Ji-Horo oleum (0.3 mol of 5Oz). Next, the mixture (the ratio of APG: H2SO4 1: 1.5) is heated to 130 ° C and maintained at this temperature for 40 minutes. CAMK yield 97%. Sulfur content 1,5%. As can be seen from the examples, methacrylamme sulphate is obtained with a yield of 97-98% with a sulfated content, by-products of 0.98-1.5% (by a known method, the yield is 95%, and the content, sulfoproneurovane ones are 5-7%). Thus, the proposed method allows, in comparison with the limestone, to increase the yield and improve the quality of the target product by reducing the formation of α-sulfonated by-products. about l 5 times. In addition, the working conditions are improved because no organic solvent is used. 58 and also simplifies the process, as it does not require regeneration of the solvent. The invention The method of obtaining sulfate, metacrnlamide by the interaction of acetone cyanohydrin with the correct acid, followed by dehydration at 120-140 ° C, differs in that, in order to increase the yield of the target product and simplify the process technology, 90-989 are used the process is carried out at 15-60 ° C, obtained by cr 646; this is the reaction mass, before degvdratsieyuyu treated with sulfuric anndrnd or oleum with an equimolar amount of sulfur-anhydride to the water of the reaction mass. sInformation sources taken into account during the examination 1. Chemical industry, 1973, N 6, p. 410-: 414. 2. US patent No. 2571194, cl. 260-486, published ... 1951. 3. Patent of Germany No. 1159428, cl. 120.21, publ. 1957. 4. Japanese patent number 25725/71, cl. 16 B 631, 12, publ. 1971 (prototype p .;