RU2379283C2 - Method of producing stable aryldiazonium salts - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method is described for producing stable aryldiazonium salts with an organic anion. The method involves two stages. First, aryldiozonium chloride is obtained by reacting chloride solution of an aromatic amine with sodium nitrite, taken in equimolar quantities at 0°C and mixing for 1 hour. Further, the obtained aqueous solution of aryldiazonium chloride is mixed with a saturated solution of 1,1,2,3,3-pentacyanopropenide pyridinium heated to 60-70°C and taken in amount of 2 mmol per 2.1 mmol of initial amine. The exchange reaction results in formation of 1,1,2,3,3- pentacyanopropenide aryldizonium of different composition depending on the structure of diazotised aromatic amines which are stable at 5-10°C for 2-3 months.

EFFECT: simple technology and improved environmental friendliness due to use of readily available starting materials and synthesis in aqueous medium.

2 cl, 1 tbl, 10 ex

Description

The invention relates to a method for producing stable aryldiazonium salts with an organic anion of 1,1,2,3,3-pentacyanopropenides of aryldiazonium, which can be used as starting materials in the preparation of dyes, photosensitive materials and biologically active compounds.

Known methods for producing aryldiazonium salts with inorganic anions, which are obtained by diazotization of aromatic amines in aqueous solutions (Patai, The chemistry of diazonium and diazo groups, Willey, New York, 1978). However, most of the salts obtained are either unstable or difficult to dissolve (Dunker M.F.W., Starkey E. B., Jenkins G. L. J. Am. Chem. Soc. 1936, 58, 2308).

A known method of producing 1,1,2,3,3-pentacyanopropenides of aryldiazonium, the closest to the claimed technical solution according to the essential features and the achieved result, we have chosen for the prototype (US Pat. Japan 2005-145879, publ. 09.06.2005). The method consists in the interaction of tetrafluoroborate aryldiazonium salt with 1,1,2,3,3-pentacyanopropenide tetramethylammonium, which are taken in equimolar amounts, are placed in a mixture of equal volumes of ethyl acetate and water. The mixture was stirred at room temperature for 1 hour, the aqueous layer was removed, after which the organic layer was washed successively with water and a saturated sodium chloride solution, dried with magnesium sulfate, filtered and evaporated. The resulting residue was recrystallized from propanol-2 to give 1,1,2,3,3-aryldiazonium pentacyanopropenide with a yield of up to 89%.

Replacing an inorganic anion (BF ₄ ^- ) with an anion of 1,1,2,3,3-pentacyanopropene upon receipt of the target product in the method described in the prototype allows to obtain aryldiazonium salts, which are more stable and can be stored for a long time (2-3 months at a temperature of 5-10 ° C).

However, known from the prototype method for the synthesis of 1,1,2,3,3-pentacyanopropenides aryldiazonium has several disadvantages:

- use for the synthesis of the starting reagent 1,1,2,3,3-pentacyanopropenide tetramethylammonium, expensive and unstable tetracyanoethylene;

- the use as reagents of tetrafluoroborates of aryldiazonium salts, poorly soluble in aqueous media and insoluble in an organic solvent, which complicates the exchange reaction.

The problem to which the invention is directed is the development of a universal, more technologically advanced and environmentally friendly method for producing stable salts of aryldiazonium, namely 1,1,2,3,3-pentacyanopropenides aryldiazonium.

The solution to this problem is provided by replacing the starting compounds during the exchange reaction between the salt of aryldiazonium and the salt of 1,1,2,3,3-pentacyanopropene.

It is proposed to use a water-soluble aryldiazonium chloride as an aryldiazonium salt, which is pre-synthesized according to the standard procedure by treating a hydrochloric acid solution of an aromatic amine with a sodium nitrite solution. At the same time, amines are used as aromatic amines that contain both electron-donating and electron-withdrawing groups, for example, aniline, n-toluidine, n-nitroaniline, n-aminosulfanilamide and others, which makes it easy to convert them to aryldiazonium chloride by treatment with sodium nitrite hydrochloric acid amine solution (examples 1-10). An unstable aryldiazonium chloride is obtained which, without intermediate isolation, is used in the exchange reaction with the organic water-soluble salt of 1,1,2,3,3-pentacyanopropene, namely 1,1,2,3,3-pentacyanopropenide pyridinium, which is easily obtained from the available starting materials substances - molononitrile, pyridine and selenium dioxide (VAKaminskii, O. Yu. Slabko, AVKachanov, BV Buhvetskii, Tetrahedron Lett. 2003, 44, No. 1, 139-140).

The above metabolic reaction with the receipt of 1,1,2,3,3-pentacyanopropenides aryldiazonium is carried out according to the scheme:

The proposed method for the synthesis of 1,1,2,3,3-pentacyanopropenides aryldiazonium has the following differences from the prototype:

A significant difference of the proposed method is the use of available starting reagents:

- chloride is used as the aryldiazonium salt, which is synthesized immediately before the exchange reaction and is used to obtain the target product without intermediate isolation from the aqueous solution;

- as a salt of 1,1,2,3,3-pentacyanopropene, 1,1,2,3,3-pentacyanopropenide pyridinium is used, the production method of which is simpler and more affordable than the method used in the prototype for the synthesis of 1,1, Tetramethylammonium 2,3,3-pentacyanopropenide.

Compared with the prototype, the exchange reaction of aryldiazonium chloride with 1,1,2,3,3-pentacyanopropenide pyridinium is carried out in an aqueous medium without the use of any organic solvents. Obtained by the proposed method, stable salts of aryldiazonium are readily soluble in organic solvents and, therefore, technologically advanced in their subsequent use as intermediate products of organic synthesis. However, the claimed method is universal - allows you to expand the number of target compounds and synthesize stable salts of aryldiazonium with a yield comparable to that specified in the prototype.

The method of synthesis of 1,1,2,3,3-pentacyanopropenide aryldiazonium is as follows. Initially, an aqueous solution of aryldiazonium chloride is prepared by a standard procedure (H.W. Grimmel, J.F. Morgan, J. Am. Chem. Soc., 1948, 70, 1750). For this, a solution of sodium nitrite is added dropwise to a hydrochloric acid solution of an aromatic amine at a temperature of 0 ° C and with stirring over one hour at an equimolar ratio of the starting reagents. Then, a saturated solution of 1,1,2,3,3-pyridinium pentacyanopropenide pyridinium heated to (60-70) ° C is poured into the resulting aryldiazonium chloride solution. The amount of 1,1,2,3,3-pentacyanopropenide pyridinium is 2 mmol per 2.1 mmol of the starting aromatic amine. The reagent ratio is due to the fact that an increase in the amount of 1,1,2,3,3-pyridinium pentacyanopropenide does not lead to a significant increase in the yield of the target reaction product and is impractical for economic reasons; a decrease in its content leads to a decrease in the yield of the product. As a result of the exchange reaction, the inorganic anion is replaced by an organic one, which reduces the solubility of the salt in the aqueous medium. The salt precipitates as a crystalline precipitate, which is filtered off, dried and purified by reprecipitation from acetone with sulfuric ether. The yield of the final product, as a rule, is more than 80% and depends on the structure of the starting aromatic amine (see table).

The table shows the spectral characteristics and yield of stable salts of aryldiazonium depending on the structure of diazotized aromatic amines.

Depending on the structure of the diazotized aromatic amine, 1,1,2,3,3-pentacyanopropenides of aryldiazonium of different compositions can be obtained by this method using diazotized aromatic amines, the structure of which includes various radicals. This is evidenced by data obtained experimentally (examples 1-10) and the data table.

The IR and NMR spectra for the obtained aryldiazonium 1,1,2,3,3-pentacyanopropenides (examples 1-10) confirm the proposed structure and indicate the salt nature of the compounds (the presence in the IR spectra of two characteristic absorption bands of the diazo group of the aromatic cation in the region 2240-2295 cm ^-1 and the cyano groups of the 1,1,2,3,3-pentacyanopropene anion - about 2200 cm ^-1 , and the presence of protons of the aromatic nucleus in the ¹ H NMR spectra). IR spectra were recorded on a Spectrum BX-II spectrophotometer ("Perkin Elmer") in KBr. ¹ H NMR spectra were obtained on a Bruker WM-250 instrument with an operating frequency of 250 MHz in acetone-D ₆ .

Stable salts of aryldiazonium obtained by the claimed method are characterized by sufficient stability and are able to be stored at a temperature (5-10 ° C) for a long time (2-3 months).

The possibility of carrying out the invention is confirmed by examples of specific performance.

Example 1. To a solution of 0.195 g (2.1 mmol) of aniline in 3 ml of concentrated hydrochloric acid and 3 ml of water while cooling with ice to 0 ° C, under stirring, a solution of 0.145 g is added dropwise over one hour (2, 1 mmol) sodium nitrite in 1 ml of water. Then, a warm (70 ° C) saturated aqueous solution of 0.5 g (2 mmol) of pyridinium 1,1,2,3,3-pentacyanopropenide in 20 ml of water is added to the reaction mixture without stopping stirring. As a result of the exchange reaction, 1,1,2,3,3-phenyl-diazonium pentacyanopropenide falls out of the reaction mixture. The precipitated salt is filtered off and washed three times with 5 ml portions of water. The resulting salt is dried and purified by reprecipitation of 1.5 ml of acetone and 10 ml of sulfuric ether. Yield 0.445 g (81% of theory).

Other examples (2-10) confirming the method are carried out analogously to example 1, using in each new experiment an aromatic amine of a new composition in accordance with the table.

The table shows the data of IR and NMR spectroscopy of the synthesized 1,1,2,3,3-pentacyanopropenides of pyridinium and their yield.

Thus, it was found that stable aryldiazonium salts can be obtained in a simpler, more economical, and more environmentally friendly way compared to the known ones. The implementation of this method on an industrial scale will eliminate the use of an expensive and unstable starting compound (tetracyanoethylene) from the process, as well as eliminate the use of flammable solvents.

Table Example R R ¹ R ² IR, cm ^{- 1} (KBr) NMR ¹ H, δ ppm (acetone-D ₆ ) Exit, % one N N N 2286, 2203 8.13 (dd, 2H, J ₁ = 8.9 Hz, J ₂ = 7.8 Hz); 8.43 (t, 1H, J-7.8 Hz); 8.90 (dd, 2H, J ₁ = 8.9 Hz, J ₂ -1.2 Hz) 81 2 N N CH ₃ 2264, 2201 2.69 (s, 3H); 7.93 (d, 2H, J = 8.9 Hz); 8.75 (d, 2H, J = 8.9 Hz) 88 3 N N OCH ₃ 2234, 2203 4.18 (s, 3H); 7.56 (d, 2H, J = 9.4 Hz); 8.81 (d, 2H, J = 9.4 Hz) 81 four Och ₃ N N 2264, 2197 4.36 (s, 3H); 7.56 (dd, 1H, J ₁ = 8.4 Hz, J ₂ = 7.4 Hz, J ₃ = 0.9 Hz); 7.80 (dd, 1H, J ₁ = 8.4 Hz, J ₂ = 0.9 Hz); 8.37 (dd, 1H, J ₁ = 8.9 Hz, J ₂ = 7.4 Hz, J ₃ = 1.6 Hz); 8.66 (dd, 1H, J ₁ -8.9 Hz, J ₂ = 1.6 Hz) 81 5 N N OH 2241, 2205 7.42 (d, 2H, J = 9.4 Hz); 8.72 (d, 2H, J = 9.4 Hz) 82 6 N N Cool 2289, 2203 8.62 (d, 2H, J = 9.2 Hz); 9.06 (d, 2H, J = 9.2 Hz) 60 7 N N NO ₂ 2298, 2209 8.88 (dd, 2H, J ₁ = 9.3 Hz, J ₂ = 2.0 Hz); 9.26 (dd, 2H, J ₁ = 9.3 Hz, J ₂ = 2.0 Hz) 84 8 N N C (O) CH ₃ 2287, 2201 2.77 (s, 3H); 8.57 (dd, 2H, J ₁ = 9.1 Hz, J ₂ = 2.0 Hz); 9.05 (dd, 2H, J = 9.1 Hz, J ₂ = 2.0 Hz) 81 9 N N SO ₂ NH ₂ 2293, 2207 7.36 (s, 2H); 8.51 (dd, 2H, J ₁ -9.0 Hz, J ₂ -2.2 Hz); 9.12 (dd, 2H, J ₁ = 9.0 Hz, J ₂ = 2.2 Hz) 79 10 (CH) ₄ (CH) ₄ N 2237, 2205 8.05 (dd, 1H, 1H, J ₁ = 8.3 Hz, J ₂ = 7.1 Hz, J ₃ = 1.1 Hz); 8.18 (m, 2H); 8.51 (brd, 1H, J = 8.3 Hz); 8.62 (dd, 1H, J ₁ = 8.3 Hz, J ₂ = 1.1 Hz); 9.06 (brd, 1H, J = 8.3 Hz); 9.39 (dd, 1H,; 1-8.3 Hz, J ₂ = 1.1 Hz) 90

Claims (2)

1. A method of obtaining stable salts of aryldiazonium through an exchange reaction of a salt of 1,1,2,3,3-pentacyanopropene and a salt of aryldiazonium, characterized in that 1,1,2,3,3-pentacyanopropene is used as a salt of 1,1,2 , Pyridinium, 3,3-pentacyanopropenide, and a water-soluble aryldiazonium chloride as the aryldiazonium salt, the reaction being carried out by the interaction of equimolar amounts of a hydrochloric acid solution of an aromatic amine and sodium nitrite, followed by stirring with the resulting aqueous solution of aryldiazonium chloride, agretogo to 60-70 ° C, a saturated aqueous solution of 1,1,2,3,3-pyridinium pentatsianopropenida in an amount of 2 mmol to 2.1 mmol of the substituted aromatic amine and isolation of the desired product by filtration. 2. The method according to claim 1, characterized in that the process is conducted in an aqueous medium.