SU384349A1 - - Google Patents

Description

one

The invention relates to the field of production of phospho-rhaiic compounds, namely, oxides of grys- (perfluoroalkyl) -ofofins of the general formula

Rf

TO/

R / where Rf-SRS, C2p5, CzP7, etc.

These compounds can be used as intermediates in organophosphorus synthesis.

A known method for producing oxide (trifluoromethyl) phosphine by hydrolysis g /) ms- (trifluoromethyl-dichlorophosphorane in the presence of oxalic acid.

When implementing this method, a multistage process arises, which is connected with the necessity of obtaining grms- (trifluoromethyl) -dichlorophosphorus-pa from trifluoroiodomethane and white or yellow phosphorus at high temperature, as well as obtaining trifluoroiodomethane. Synthesis of oxides of grc- (perfluoroalkyl) -phosphines, where the number of carbon atoms in the perfluoroalkyl groups is two or more, may be associated with even greater difficulties.

In order to simplify the process, a new method for producing oxides of tris (p & fluoroalkyl) -phosphines is proposed. It consists in the fact that trialkylphosphine oxides are subjected to

electrochemical fluorination in anhydrous hydrogen fluoride. The process of electrochemical fluorination of trialkylphosphine oxides is carried out in standard equipment used to obtain

perfluorinated organic compounds by electrochemical fluorination.

Fluoroplast-4 and fluoroplast-3 are used as gasket and sealing materials. To facilitate dosage of baseline.

The trizhilphosphine oxides in the electrolyzer are pre-dissolved in anhydrous hydrogen fluoride.

The process of electrolysis can take place either intermittently or continuously. When conducting electrolysis, a rather wide range of current densities from 0.02 to 0.05 A / cm can be used with a voltage across the electrodes of 5.0-6.0 volts.

Significant electrolyte pitch and

corrosion during electrofluorization of trialkylphosphine oxides is not observed. The yield of oxides (perfluoroalkyl) -phosphines varies from 30 to 60% of the theoretical one. As by-products

Fluorination reactions are mainly produced by perfluorocarbons and some fluorophosphorus-containing compounds.

The selection of the desired products from the mixture obtained from the electrolysis of perfluorinated compounds, soda, and 80% and more than oxides of tris (perfluoroalkyl) -phosphines, is carried out by known methods, for example, by distillation.

The proposed method of producing oxides of trys- (perfluoroalkyl) -phosphinoB is characterized by the simplicity and possibility of using hydrocarbon analogues of the obtained products as starting compounds.

Example. Electrochemical fluorination of tripropylphosphine oxide is carried out in a 1.2 liter batch type electrolysis using 750 cm nickel anodes and steel cathodes. Electrolysis installation is mounted and sealed using fluoroplast-4 materials. The initial concentration of tripropylphosphine oxide in hydrogen fluoride is 15 wt. %, which was subsequently maintained within the limits of Г5-20% due to periodic feeds with a similar raw material (80% solution of tripropylphosphine oxide in hydrogen fluoride).

Process conditions: current density of 0.03 voltage on the electrodes 5.5-5.8 in; electrolyte temperature 18-20 ° C; temperature of the reverse refrigerator 25-30 ° C; the current of a two-half-period rectification (from S-Elenovyh rectifiers type VSMP-200).

The electrolysis process is carried out periodically with the electrolyzer turned off overnight. As the electrolyte level decreases, the required amount of hydrogen fluoride is added to the electrolyzer. Liquid Perfluorinated products (raw) are collected at the bottom of the cell, from which they are periodically drained.

In total, during the experiment, 2660 a / h of electricity was passed through the элект electrolyte and 356 g of raw material was obtained, the average output of which

amounted to 0.134 g / a - an hour or 52.2% of the theoretical in substance.

Analyzes of the average raw sample method

GLC showed the presence of 96% perfluoro5 propyl phosphine oxide in it, the yield over the time of the experiment

50.1% perfluoropropylphosphine oxide; m.p.

150-15 ° C; p2o 1,2d48; d | ° 1,8698.

Found,%: P 5.86, 5.66; C 19.25, 19.32; F 70.78, 70.70; 71.36; MRc 55.04.

CsFziPO.

Calculated,%: P 5,59; C 19.48; F 72.1; MRo 55.2.

In the IR spectra of perfluoropropylphosphine oxide, there is an intense absorption in the range of 5,132 cm - characteristic of the bond, as well as 1140 ohm-1 and 1220 cm-, corresponding to the C-F bond of m.

Purification of the product from impurities is carried out by rectification on a glass column with a Christmas tree deflower height of 50 cm.

The composition of electrolysis gases formed during electrofluorization of tripropylphosphine oxide varies between: hydrogen 88.0-191.0%, fluorocarbons (mainly octafluoropropane) 11.0-8.2%. In addition, an insignificant amount of oxidizing agents of 0.3-0.5% is present in gases, in terms of fluoride monoxide) and impurities of other gaseous electrolysis products.

The electrolysis process proceeds without a noticeable increase in voltage on the electrodes, without tarring the electrolyte and corrosion of the anodes.

Subject invention

A method of producing oxides of rpwc- (perfluoroalkyl) -phosphines, characterized in that, in order to simplify the process, the trialkylphosphine oxide is subjected to electrochemical fluorination in anhydrous hydrogen fluoride medium, followed by separation of the target product by known methods.