SU1100897A1 - Method of producing difluorphosphoranes - Google Patents

Abstract

METHOD FOR OBTAINING DIFFLUOROPHOSPHORANES of general formula R. R PF. where R and R are low alkyl or phenyl using tertiary phosphine, characterized in that, in order to simplify the process and increase the yield of the target products, the tertiary phosphorus is subjected to electrochemical oxidation in the platinum electrode in the medium of dry acetonitrile in the presence of tetrafluoroborate tetraethylammonium and fluoride n-amylamonium at room temperature in an inert gas atmosphere.

Description

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The invention relates to the chemistry of organophosphorus compounds with a C-P bond, namely to a new method for the production of difluorophosphoranes of general

TJ Formulas

R-PP,. "

where RHR is lower alkyl or phenyl which I are highly reactive compounds and can be used as intermediate products of organophosphorus synthesis.

There are known methods for producing difluorophosphoranes by the action of trifluoride phosphate on chlorophosphines, by the interaction of fourfluoride sulfur with phosphines or oxides of tertiary phosphines.

The closest to the described invention to the technical essence and the achieved result is a method of obtaining difluorophosphoranes, which consists in the fact that tertiary phosphine is subjected to interaction with ery in an environment of benzene or hydrogen sulfide with heating, followed by treatment of the resulting phosphin sulfide with antimony trifluoride

The disadvantages of this method include the two-stage process, as well as the need to use antimony trifluoride, which has strong toxic properties. The formation of fine antimony along with the target products interferes with the thorough purification of the target products, the yield of which is 57-62%.

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

The goal is achieved by the described method of obtaining difluorophosphoranes of the general formula, which consists in the fact that tertiary phosphine is subjected to electrochemical oxidation on a platinum electrode in dry acetonitrile in the presence of tetraethylammonium tetrafluoroborate and fluoride n-amyl ammonium at room temperature in an inert pelvic atmosphere. A distinctive feature of the method is the electrochemical oxidation of tertiary phosphine and the process under the conditions described.

08972.

The described process for the preparation of difluorophosphoranes makes it possible to simplify the process of obtaining the desired products, since it is one-step,

. involves the use of a non-toxic fluorination reagent and proceeds selectively, i.e. with the formation of mainly one target product, as a result, the isolation of target products, due to the absence of contamination by their by-products, is simplified. The desired products are formed in pure form with a yield of 69-85%. Education di-g

fj fluorophosphoranes under the described conditions is not obvious, since there is a known method for producing dialkyl trifluorophosphores by the electrochemical oxidation of secondary phosphines on a platyrode in dry acetonitrile at room temperature in the presence of tetraethylammonium and dry pyridine.

Electrochemical oxidation

25 tertiary phosphines under the conditions of a known method do not lead to the synthesis of difluorophosphorane. Along with tetraethylammonium tetrafluoroborate and other substances, the introduction of the desired products into the electrochemical cell, along with tetraethylammonium tetrafluoroborate and other substances. In this case, a stronger fluorinating agent is needed, which is n-amylammonium fluoride, and tetraethyl ammonium tetrafluoroborate plays only the background role, as it is more soluble in acetonitrile.

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

For the electrochemical synthesis of trialkyl difluorophosphoranes, a Teflon electrolytic cell with

 a working volume of 50 cm with separated anode and cathode spaces. The electrolysis is carried out in an inert gas atmosphere, such as dry argon, at room temperature. During electrolysis, the solution is stirred using a magnetic stirrer. The anode is a platinum cylinder with a surface of 30 cm, the cathode is a nickel spiral with a surface of 5 cm. Working potential

the electrode is measured relative to a silver electrode with a 0.01 M solution of silver nitrate in acetonitrile. Catholyte contains 10 ml of a saturated J solution of pyridinium tetrafluoroborate in acetonitrile. After the end of the electrolysis, the products are extracted with absolute hexane, the hexane is distilled off, and the distillate products are distilled under vacuum (3-20 mm Hg). Example 1. Obtaining triethyldifluorophosphorane. The working solution (anolyte) with a total volume of 30 ml was prepared by dissolving 5.16 g (0.025 mol) of tetraethylammonium tetrafluoroborate in acetonitrile and 10.72 g (0.1 mol) of fluoride n-amyl ammonium was added. After passing dry argon through the electrolyte for 30 minutes, 11.82 g (0.10 mol) of triethylphosphine is added to the anolyte. The electrolysis is carried out in a galvanostatic mode at a current density of 6.7wA / cM. The potential of the working electrode varies from + 0.8 to 1.4 V. 2.84 electricity is passed through the electrolyte. 6.24 g (80%) of triethyldifluorophosphoran are obtained. B.p. (20 mm Hg); n | ° 1,4062. Found,%: C 46.25; H 9.65; P 18.64. Calculated,%:, 15; H 9.68; R 19.83. CgHjsPFa. NMR P-spectrum,,;, d ;. : -13; 570 Hz. NMR F-spectrum, M: A- Example 2. Preparation of tripropylfluorophosphorane. A working solution (anolyte) with a total volume of 30 ml was prepared by dissolving 5.16 g (0.025 mol) of tetraethylammonium tetrafluoroborate in acetonitrile and 10.72 g (0.1 mol) of n-amyl ammonium fluoride was added. After passing through the electrolyte of dry argon for 30 minutes, 9.62 g (0.06 mol) of tripropylphosphine was added to the solution. The electrolysis was carried out in galvanostatic mode at a current density of 5.0 nA / cm. 1.75 Ah of electricity is passed through the electrolyte. The potential of the working electrode varies from +0.9 to 1.6 V. 4.84 g (82%) of tripropyl difluorophosphorane are obtained, b.p. .. / 9 mm Hg; 1.4249. Found,%: C 54.48; H 10.61; R 14.32. Calculated,%: C 54.53; H 10.68; R 15.62. C.HiiFF,. 974 NMR P-spectrum, “UM x-Zr, p 580 Hz. NMR F-spectrum, „-.d. : +42. IR spectrum,), 842 (P - F). P. Example 3. Preparation of tildifluorophosphorane tributane. A working solution (anolyte) with a total volume of 30 ml was prepared by dissolving 5.16 g (0.025 mol) of tetraethylammonium tetrafluoroborate in acetonitrile and 10.72 g (0.1 mol) of n-amyl ammonium fluoride was added. After passing through electrolyte-dry argon, 10.12 g (0.05 mol) of tributylphosphine are added to the solution for 30 minutes. The electrolysis is carried out in galvanostatic mode at a current density of 3,) A / cm. In this case, the potential of the working electrode varies from +0.9 to +1.4 V. 1.54 A h of electricity is passed through the electrolyte. Obtain 5.12 g (85%) tribzpgildifluorophosphorane; / 1 mm PT.CT.J h 1.4332. Found,%: C 60.05; H 11.43; R 11.13. Calculated,%: C 59.98; H 11.32; R 12.89. NMR P - spectrum,. . : -15; P-F 580 Hz. NMR F-spectrum, „. D. : +43. Example 4. Obtaining tri-amyldifluorophosphorane. A working solution (anolyte) with a total volume of 30 ml was prepared by dissolving 5.16 g ((0.025 mol) of tetraethylammonium tetrafluoroborate) in acetonitrile and 10.72 g (0.1 mol) of fluorine n-amylammonium was added. After passing argon through the electrolyte for 30,22 g (0.05 mol) of triamylphosphine are added to the solution in 30 minutes. The electrolysis is carried out in galvanostatic mode at a current density of 3.3 "hqA / cm. The potential of the working electrode varies from 0 to +1.6 B. Through the electrolyte, 1.5 Ah of electricity is passed in. 5.53 g (78%) of triamyldifluorophosphorane are obtained, bp 129 UO C (3 mm Hg). t.); and 1.4420. Found,%: C 63.75; H 11.74; P 9.32. Calculated,%: C 63.80; H 11.78; R 10.97. 11 NMR P -spectrum, („d: -15; 3. 580 Hz. NMR F -spectr, 8„, d.: +41. IR spectrum, V, cm-: 834 (PF). Example 5. Preparation of trifluorofluorophosphorane A working solution (anolyte) with a total volume of 30 ml is prepared by dissolving 5.16 (0.025 mol) of tetraethylammonium tetrafluoroborate in acetonitrile and 10.72 g (0.1 mol) of fluorine n-AFF ammonium are added. After skipping the cans through a solution of dry of argon for 30 min. 10.82 g (0.05 mol) triphenylphosphine is added to the anolyte. The electrolysis is carried out in galvanostatic mode at a current density of 3, Зг 1 | А / см. At the same time, the potential of the slave of the electrode varies from +1.1 +1.6 V. I pass 1.51 A h of electricity through the electrolyte. 4.62 g (71%) of triphenyldifluorophosphorane are obtained. M.p. . Found,%: from 72.15; H 5.00; R 9.61. Calculated,%: C 72.00; H 5.03; R 10.31. 18 NMR P-spectrum, 8 "d. 680 Hz, NMR F spectra VSF rx: +39. Example 6. Preparation of phenyldiethyldifluorophosprane. A working piacTBOp (anolyte) with a total volume of 30 ml was prepared by dissolving 5.16 g (0.025 mol) of tetrathylammonium tetrafluoroborate in acetonitrile and 10.72 g (0.1 mol) of n-amyl ammonium fluoride added. After passing dry argon through the electrolyte, within a period of 30 minutes, 8.54 g (0.03 mol) of phenylethylphosphine was added to the solution. The electrolysis is carried out in galvanostatic mode at a current density of 3.3 tA / cm. The potential of the working electrode varies from +1.2 to +1.7 V. 1.54 electricity is passed through the electrolyte. 3.74 g (69%) of phenyldistidifluorophosphorane are obtained. Bp 62C (2 mm Hg) K 1.4688. Found,%: C 53.65; H 8.36; R 16.41. Calculated,% C 53.33; H 8.39; R 17.19. CeH ,, PF.,. NMR p. - Spectrum, & „..: -38; RR - 620 Hz. NMR F-spectrum, („. D .: +40.

Claims (1)

METHOD FOR PRODUCING DIFTORPHOSPHORANES of the general formula R — PF ₂ where R and R ¹ - low alkyl or phenyl, using tertiary phosphine, characterized in that, in order to simplify the process and increase the yield of target products, tertiary phosphine is subjected to electrochemical oxidation in a platinum electrode in a medium of dry acetonitrile in the presence of tetraethylammonium tetrafluoroborate and n-amylavonium fluoride at room temperature in an inert gas atmosphere. | s