SU950717A1 - Process for producing 4-nitroso diphenylamine - Google Patents

Description

The invention relates to organic synthesis, in particular, to a method for producing 4-nitrosodiphenylamine, which is an intermediate in the production of rubber antioxidants - N-phenyl, N-alkyl-g1-phenylenediamines.

A known method for producing 4-nitroso di-enylamine by rearranging N-nitrosodiphenylamine in a mixture of aliphatic alcohol and water l.

Despite the use of 5 mol of hydrogen chloride per 1 mol of nitrosoamine, the process takes 16 hours, the yield and quality of the product are low.

Compared to the conventional rearrangement method, anhydrous alcohols consume much more hydrogen chloride, and as a result more alkali is used to neutralize it. The disadvantage of the method of producing 4-nitrosodiphenylamine with the use of hydrogen chloride in an alcohol or water-alcohol solution is the incomplete rearrangement of the original substance, due to the fact that it is moderately soluble in alcohol and during the reaction of its set are coated with 4-nitrosodiphenylamine, an insoluble hydrochloride. Therefore, a large amount of fine detail is added to the dispersion of N-nitrosodiphenylamine in alcohol 2J, which is achieved by feeding molten N-nitrosodiphenylamine to cold alcohol, preferably to butanol.

According to this experience, a high degree of reaction of the starting material can be achieved only in a reactor with a very intensive mixing of a slurry-like reaction mixture, which is a very difficult problem due to the presence of corrosive hydrogen chloride.

15

The known method of rearranging N-nitrosodiphenylamine in a mixture of aliphatic alcohol with a polar solvent, which dissolves N-nitrosodiphenylamine well, i.e. reaction

20 flows in a homogeneous environment.

Ether, chlorinated hydrocarbons and aromatic hydrocarbons are recommended as a less polar solvent.

25

The known method consists in using a mixture of chloroform and methanol in a volume ratio of 5.8: 1.

At 25-30 ° C and a HC1: N-nitrosodiphenylamine molar ratio of 1: 3

30 The rearrangement ends in 77.5 hours. The reaction mixture is subjected to an aqueous solution of sodium alkali, as a result of which not only hydrogen chloride, but also 4-nitrosodiphenylamine is neutralized to the sodium salt. Dissolving 4-nitrosodiphenylamine is not only a separation process, but also a purification process, since the greatest amount of unreacted N-nitrosodiphenylamine and some products of reaction reactions remain in chloroform. From an aqueous solution of the sodium salt, pure 4-nitrosodiphenylamine can be obtained with precipitated acid, however, the sodium salt solution is directly reduced by sulphide to 4-aminodiphenylamine. Chlorobenzene is also used as a chlorinated solution gel in the rearrangement; under the same conditions, rearrangements are carried out in chloroform t 3. The closest to the technical approach to the proposed method is that the rearrangement of N-nitrosodiphenylamine is carried out in a toluene-methanol mixture in a volume ratio of 3: 1. diluted solutions of about 0.2-2 g of N-nitrosodiphenylamine per 100 MP solvent at 30, 40 and 50 ° C. Based on a detailed study of the rearrangement of N-nitrosodiphenylamine to 4-nitrosodiphenylamine in toluene-methanol medium catalyzed by hydrogen chloride, it was found that the process rate increased with the concentration of the N-nitro-zodiphenylamine solution 4. The concentration of the initial solution of 0.23-2.3 wt.% - and the speed of the process reaches a high value, thanks to a high concentration of hydrogen chloride. The reaction temperature above 30 ° C is not suitable for the production of 4-nitrosodine vitamin, since at a higher temperature, by-products, primarily diphenylamine, as well as substances containing chlorine associated with carbon, are formed during peregrugirovaniya. When rearranging, the precipitated crystalline 4-nitrosodiene phenylamine adheres to the walls of the reaction vessel, which causes considerable difficulties, namely in a continuous process. The purpose of the invention is to eliminate side processes and increase the yield of the target product. The goal is achieved by the fact that according to the method of obtaining 4-rozodiphenyls by treating N-nitrosodiphenylamine with hydrogen chloride in a toluene-methanol mixture containing 26-50% by volume of methanol with an initial concentration of N-nitrosodiphenylamine 28-34% by weight of solution . Gaseous hydrogen chloride is supplied to a solution of N-nitrosodiphenylamine in a mixed solution at 15-25 ° C and after that the reaction mixture is kept at 20-2 ° C for a few more hours; the rearrangement time is determined by the HC1: N-nitrosodiphenylamine ratio, the reaction temperature and the initial concentration of nitrosodiphenylamine and ranges from 2 to 10 hours. Suitable HNMI by HCI .: N-nitrosodiphenylamine is 1.2-2, preferably 1.3- 1.5. Hydrogen chloride can be added to the reaction mixture as a solution in methanol. In this case, N-nitrosodiphenylamine is dissolved only in toluene. The rearrangement of N-nitrosodiphenylamine can even be carried out continuously in a cascade of reactors with agitators. A toluene solution of N-nitrosodiphenylamine, methanol and hydrogen chloride, or preferably a solution of hydrogen chloride in methanol, are fed into the first cascade reactor. The mixture moves from one reactor to the next differential or is pumped through it. High yield and good quality can only be obtained with a large number of reactors (4-8). The complete reaction of N-nitrosodiphenylamine requires, for example, in a three-membered cascade twice as long as the reaction time, as compared with a batch reactor, which contributes to the formation of by-products containing chlorine associated with carbon. The porridge-like crystalline mass of 4-nitrosodiphenylamine hydrochloride is best processed by the action of sodium alkali in excess in an aqueous solution. The contaminants will remain in the layer from the aqueous solution of 4-nitrosodiphenylamine. By neutralization, free 4-nitrosodiphenylamine is obtained with a mp. 142145 ° C at the exit 92-97%. The 4-nitrosodiphenylamine sodium salt solution is suitable for catalytic reduction to 4-aminodiphenylamine. Example 1. A flask with a capacity of 5 l with a root stirrer was filled with a solution of 530 g of N-nitrosodiphenylamine in 870 g of toluene and 380 g of methanol (solution concentration 31.7 wt.%) And at 15-20 ° C, the mixture was cooled, supplied 1 155 g of hydrogen chloride gas and the reaction mixture is kept at 23-24 ° C for another 5 hours. Then, after cooling, the mixture is mixed with 300 g of sodium alkali dissolved in 2 liters of water. After thorough mixing, the mixture is allowed to stand for the purpose of separating the aqueous layer from the toluene layer. 4-Nitrosode is precipitated from the aqueous layer with sulfuric acid.

Claims (3)

Claim 1. The method of producing 4-nitrosodiphene; nilamine by treating N-nitroeodiphenylamine with hydrogen chloride in a mixture of toluene and methanol, characterized in that, in order to eliminate side processes and increase the yield of the target product, the process is carried out with a volume ratio of toluene: methanol 1, 0-2,9, concentration of N-nitrosodiphenylamine in solution 28-34% strength by weight, a molar ratio of hydrogen chloride and N-nitroso diphenylamine 1,2 ^s0:. 2 at 15-28 ^< 's. 2. The method of Pop. 1, distinguishing with the fact that hydrogen chloride is fed into the reaction mixture in a gaseous state or in the form of a solution 35 in methanol. 3. The method according to claims 1 and 2, characterized in that the process is carried out continuously in the cascade of reactors with the number of reactors in cascade 4-8, moreover, a solution of N-nitrosodiphenylamine in toluene is fed into the first reactor, and hydrogen chloride in methanol into the first or to the second reactor.