SU755795A1 - Method of preparing phosphonium salts - Google Patents

Description

The invention relates to the field of chemistry of organophosphorus compounds with a C-P bond, in particular, to an improved method for the preparation of phosphonium salts of the general formula

{К _Э Р ⁺ -К ^{1 * * * 5} ] А5

where B is alkyl or phenyl,

B ¹ is phenyl, thienyl or furyl,

A '- perchlorate- or boron fluoride-aion.

These compounds are used as medicines, pesticides and other physiologically active substances, as well as intermediates for organophosphorus synthesis.

A method of producing aromatic phosphonium salts by reacting tertiary phosphate ₁₅ Finns with aryl halides. These reactions, as a rule, are carried out when heated in the presence of catalysts, for example, aluminum chloride or nickel salts of HL.

The closest to the invention by _Μ cal technical essence and achieved result. is a method of obtaining phosphonium salts, which is that the tertiary phosphine is subjected to electrochemical oxide2

on the platinum electrode in an 18–20-fold excess of an aromatic or heterocyclic compound in an acetonitrile medium in the presence of a perchlorate or boro-fluoride salt and pyridine - as a proton acceptor. The process is carried out at room temperature in an inert gas atmosphere [2].

The disadvantages of this method include the need to use an expensive platinum electrode and toxic pyridine, as well as the relatively low yield of the target products (15-72%).

The aim of the invention is to simplify the process and increase the yield of target products.

This goal is achieved by the described method of obtaining phosphonium salts, which consists in the fact that tertiary phosphine is subjected to electrochemical oxidation on a glass-graphite electrode, preferably in a 10-30-fold excess of an aromatic or heterocyclic compound, in an acetonitrile medium in the presence of a perchlorate salt or borfluoride and a proton acceptor - trisodium3

phosphate. The process is conducted in an inert gas atmosphere, preferably at 2O-4O ° C.

The distinctive features of the method include using a glass-graphite electrode as a solid electrode, trisodium phosphate as a proton acceptor and conducting the process in the indicated conditions.

The described method allows to obtain salts of phosphonium in pure form and with a higher yield (up to 95%) compared with the previously known method. Its advantage is also the fact that a cheap glass-graphite electrode can be used as an electrode, rather than a platinum electrode, and as a proton acceptor produced in industry in large quantities trisodium phosphate, and not toxic, more expensive pyridine.

The structure of the compounds obtained is proved by IR and NMR spectroscopy data and is confirmed by the results of elemental analysis.

The output of phosphonium salts obtained by the proposed method and the known [2].

Compound Output, % The proposed method Method according to [2] [ shu; 85 72 ! vh ~ 86 67 + п п пкю-А> ь э о ³ shu; 80 15 [and "Bu ₃ P ~ Tb 95 16.5

Example 1 .. Getting perchlorate three _; phenylthienylphosphonium.

For the electrochemical synthesis using an electrolytic cell with a work volume of 80 cm ³ 'with separated anodic and cathodic spaces separated by a porous glass partition. Electrolysis is carried out at 40 ° C in an argon atmosphere. During electrolysis, the working electrolyte solution is stirred with a magnetic stirrer. The anode is a disk of glass-graphite grade SU-2000 with a surface of 30 cm ² , the cathode is a nickel spiral with a surface of 10 cm ² . Working electrode potential

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measured relative to silver wire in a 0.01 M solution of silver nitrate in acetonitrile.

The working solution (anolyte) with a total volume of 5 to 50 ml is prepared by dissolving triphenylphosphine in acetonitrile'2 g (0.0076 mol),

12.6 g (0.15 mol) of thiophene and 6.4 g (0.052 mol) of sodium perchlorate. As a proton acceptor, 12.3 g (0.075 mol) of 10% aqueous trisodium phosphate are introduced into the anolyte. Catholyte contains>

20 ml of a saturated solution of sodium perchlorate in acetonitrile. The electrolysis is carried out in galvaiostatic mode at a current density of 1.7 mA / cm ² . Through the electrolyte pass 15 0,41 Ah of electricity. The potential of the working electrode in this case varied from 0.7 to 1.1 V.

At the end of the electrolysis, the electrolyte is filtered off from sodium phosphate, and the solvent and unreacted thiophene are removed in vacuo. On the 20th day of the separation of the sodium perchlorate background salt from the electrolysis products, methylene chloride is added to the residue obtained. Then, after vigorous stirring, the background salt is filtered off. After that, methylene chloride is distilled off in vacuum, and the dry residue is treated with benzene to remove triphenylphosphine oxide and unreacted triphenylphosphine soluble in it. Then the precipitate is filtered off, recrystallized twice from 30 dimethylformamide, washed with ether and dried in vacuum at 70 ° C for 2 hours.

2.87 g (85%) of triphenylthienylphosphonium perchlorate are obtained, m.p. 236-238 ° C (with decomposition).

 35% found: C 59.65; H 4.02; P 7.24;

Ce 8.68; 3 7.23.

C2 ₂ H1 ₈ O ₄ 5С1Р.

Calculated,%: C 59.38; H 4.05; P 6.97;

5 7.20; From 7.98. .

40 NMR ³ * P-spectrum, (G ppm (solution in nitromethane): -16, IR spectrum, t ?, cm ^-1 : 1440 (P-Pb); 692, 753, 1465, 1585, 3060 (monosubstituted benzene ring); 735, 3080 (thiophene ring); 625, 1100 (C10 ₄ -).

Example 2. Preparation of triphenylthienylphosphonium tetrafluorobromide.

The electrolysis is carried out in the same electrolytic cell as described above at _about 40 ° C. A working solution (anolyte) with a total volume of 50 ml is prepared by dissolving 2 g (0.0076 mol) of triphenylphosphine, 12.6 g (0.15 mol) of thiophene and 8.67 g (0.04 mol) of tetraethylammonium boron fluoride in acetonitrile. As a proton acceptor, 12.3 g (0.075 mol) are introduced into the anolyte. anhydrous trisodium phosphate. Catholyte contains 20 ml of a saturated solution of boron tetrahemyl ammonium in acetonitrile. Electrolysis is carried out in galvanostatic mode with a raft5

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1.7 mA / cm ² current. 0.41 4 · 4 electricity is passed through the electrolyte. The potential of the working electrode varies from 0.76 to 1.2 V. At the end of the electrolysis, the electrolyte is filtered off from trisodium phosphate, and the solvent and unreacted thiophene are distilled off in vacuum. The dry residue is boiled with 200 ml of water to separate the background salt of tetraethylammonium boron. The residue is filtered off, washed with alcohol and treated with benzo-, scrap to separate triphenylphosphine oxide and unreacted triphenylphosphine soluble in it. The benzene insoluble precipitate is filtered and recrystallized twice from dimethylformamide. The resulting product was washed with ether and dried at 70 ° C for 2 hours. 2.83 g (88%) of triphenylthienylphosphonium tetrafluoroboride was obtained, mp. 227-228 ° C.

Found,%: C 61.35; H 4.23; P 7.28; 20

5 7.83.

C ₂₂ H ₁₈ VZRRR ₄ .

Calculated,%: C 61.14; H 4.17; P 7.17;

5 7.41.

NMR ³¹ P-spectrum (in acetonitrile) ^, ppm: 25

-15. IR spectrum, -9, cm '¹; 1430 (R-PH), 697, 755, 1460, 1583, 3060 (monosubstituted benzene

“Ring) 730, 3090 (thiophene ring).

Example 3. Obtaining tributylphenyl perchlorate. thirty

The electrolysis is carried out in the same electrolytic cell as described above. The process is carried out at 20 ° C in an argon atmosphere.

The working solution (anolyte) is prepared by dissolving 2.02 (0.01 mol) of tribune- ₃₅ tilphosphine, 20.4 g (0.3 mol) of furan and 6.12 g (0.05 mol) of sodium perchlorate in acetonitrile. As a proton acceptor, 9.83 g (0.06 mol) of anhydrous trisodium phosphate is introduced into the anolyte. The catholyte contains 20 ml of a saturated solution of ₄₀ sodium perchlorate in acetonitrile. The electrolysis is carried out in galvanostatic mode at a current density of 1.7 mA / cm ² . Through the anolyte pass 0,53 A · h of electricity. The potential of the working electrode changes from - ₄₅

0.9 to 1.2 V.

At the end of the electrolysis, the electrolyte is filtered off from trisodium phosphate, and the solvent and unreacted furan are removed in vacuo. To separate the background salt of sodium perchlorate from the products of electrolysis, methylene chloride is added to the residue obtained. After vigorous stirring, the background salt is filtered off and the methylene chloride is removed in vacuo. The residue obtained is dissolved in ethyl alcohol and cooled with liquid nitrogen. The crystals thus formed are filtered and recrystallized from acetonitrile.

2.95 g (80%) of tributylpuryl phosphonium perchlorate are obtained, mp. 230-232 ° C. Literary data: so pl. 23O-233 ° C, NMR ³¹ P-spectrum (solution in nitromethane) (G, ppm: - 34, IR spectrum, "9, cm ^-1 : 3090 (stretching vibrations C – H of the furyl radical) 625, 1092 (C10 ₄ -).

Example 4. Obtaining tributylphenylphosphonium perchlorate.

The electrolysis is carried out in the same electrolytic cell as described above at 20 ° C in an argon atmosphere. The working solution (anolyte) with a total volume of 50 ml is prepared by dissolving in acetonitrile 3.03 g (0.015 mol) of triphenylphosphine, 23.43 g (0.3 mol) of benzene and 9.18 g (0.075 mol) of sodium perchlorate. Catholyte contains 20 ml of a saturated solution of sodium perchlorate in acetonitrile. The electrolysis is carried out in galvaiostatic mode at a current density of 3.34 mA / cm ² . 0.39 Ah of electricity is passed through the electrolyte. In this case, the potential of the working electrode increases from 0.9 to 1.4 V. Then c. 12.29 g (0.075 mol) of anhydrous trisodium phosphate is injected into the working solution to neutralize the perchloric acid formed and electrolysis is continued. Upon reaching the potential of the working electrode 1.4 V electrolysis is completed. The total amount of electricity passed through the electrolyte is 0.77 Ah.

The electrolyte is filtered off from trisodium phosphate, and the solvent and unreacted benzene are removed in vacuo. To separate the background salt of sodium perchlorate from the products of electrolysis, methylene chloride is added to the residue obtained. After vigorous stirring, the background salt is filtered off and the methylene chloride is distilled off. The residue is dissolved in a small amount of ethanol and poured into a glass, where, after rubbing "on the walls with a glass rod, crystals fall out, which is filtered and recrystallized from ethyl alcohol. Then the crystals are washed with ether and dried in vacuum at 70 ° C for 1 hour.

5.39 g (95%) of trnbutnylphenylphosphonium perchlorate are obtained, mp. 122-123 ° C.

Found,%: C 57.36; H 8.53: P 8.17;

Ce 9.94 C 18 ^ 32 ^ 4 C1P.

Calculated,%: C 57.24; H 8.48; P 8.15;

CE 9.32.

NMR ³¹ P-spectrum (solution in nitromethane), V, ppm: -30. IR spectrum, "9, cm" ¹ : 1440 (P — PH):

696, 756, 1464, 1590, 3068 (monosubstituted benzene ring); 625, 1100 (C10 ₄ -).

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Claims (2)

Claim I. The method of obtaining phosphonium salts of the General formula ' [in ₃ p * -HH-, where B is alkyl, or phenyl, ₅ B ¹ is phenyl, thienyl or furyl, And "- perchlorate or boron fluoride anion, electrochemical oxidation on a solid tertiary phosphine electrode in an excess of aromatic or heterocyclic compounds in acetonitrile in the presence of a perchlorate salt or boron fluoride and a proton acceptor in an inert gas atmosphere, characterized in that, in order to simplify the process and increase the yield of the target products, as a solid electrode, a hexlographite electrode is used and as a proton acceptor, trisodium phosphate. 2. The way pop. 1, characterized in that the aromatic or heterocyclic compound is used in a 10-30 fold excess and the process is carried out at 20-40 ° C. Sources of information taken into account in the examination 1. Purdela, D., R. Valchanu. Chemistry of Organic Phosphorus Compounds, “Chemistry”, 1972, p. 222. 2. USSR author's certificate on the application ’2459928 / 23-04, cl. C 07 R 9/54, 1977 (prototype).