SU369112A1 - METHOD OF OBTAINING FLUOROCALON LIQUIDS - Google Patents

Description

one

The invention relates to methods for producing fluorocarbon liquids that may be used in engineering as heat carriers for dielectrics.

A known method for producing fluorocarbon liquids by electrochemical fluorination of HF esters of acids containing 1 to 2 carbon atoms in the alcohol part of the molecule. But insufficiently high physico-chemical characteristics of the resulting liquids limit their use in engineering.

It is proposed to use in the process esters containing in the alcohol part of the molecule from 3 to 8 carbon atoms.

Electrochemical fluorination of esters of carboxylic acids containing 3 or more carbon atoms in the alcohol part of the molecule, along with the fluoroanhydrides of the corresponding polyfluoroacids, which are formed from both the acid and alcohol parts of the molecule of the starting ester, give rather high yields of non-acid perfluorinated compounds with the same number of carbon atoms in the molecule as in the original ether molecule. According to the data of analytical studies, these compounds, containing in

In its composition, only fluorine, carbon and oxygen are a mixture of perfluorinated cyclic or linear ethers.

In the case of fluorination of dibasic acid esters, the resulting non-acidic products are mainly represented by a mixture of perfluoro compounds containing the number of carbon atoms in a molecule both equal to their number in the dibasic ester molecule and equal to the number of carbon atoms in the corresponding monobasic acid ester molecule. available esters of aliphatic, aromatic, alicyclic acids with hetero-atoms are used as starting materials; All of these products are widely commercialized as plasticizers, solvents, synthetic oils, etc.

Example 1. Electrochemical fluoridation of phthalic acid dibutyl ester is carried out in a 1-liter batch electrolyzer. The process is carried out continuously with periodic feedstock feedstock. Process conditions: the concentration of organic matter in the electrolyte is 25 ± 3%, the temperature of the electrolyte is 25-28 ° C, the temperature of the reflux condenser is from -22 to -20 ° C; the anodic current density is 0.0o a / cm-, the voltage on the electrodes is 5.8-5.9 volts. Under these conditions, 3000 a / h of electricity per 1 liter of electrolyte is missed, and the average yield of liquid perfluoroproducts drained from the bottom of the electrolyzer is 0.39 g / a-hour. At the same time, the corrosion of the electrodes, the decrease in the yields of perfluoroproducts over time, the growth of voltage on the electrodes and other abnormal effects during the process are not observed.

The mixture of liquid perfluoroproducts obtained as a result of the electrolyzer (crude) is subjected to fractionation, with the following fractions being obtained:

I. Fraction 60 120 ° C-40.6 wt. % raw. The method of gas-liquid chromatography, IR and NMR spectroscopy has shown that the main components of this fraction are perfluoro-CYCLO-, hexanmono- and dicarboxylic acids, perfluorocyclohexane, perfluoromethylcyclohexane.

II. Fraction 150-f-170 ° C-18.7 wt. % raw. The specific gravity is 1.852 g / cm, the temperature of thickening is below -80 ° C.

IR spectra - the complete absence of absorption-- -and in the region of 2700-3100 cm, i.e.

/ H -. / N. “-С С (-С-Н-зей.

I N, / N, /

Elementary analysis revealed the absence of hydrogen. The molecular weight of 554 found by vapor density (slightly different, by 2%, from the calculated 554 for a compound or isomeric compounds with 5 and 7 membered rings).

NMR spectroscopic data also support the above isomeric structures.

III. Fraction 170 190 ° C-21.5 wt. % raw. According to IR and NMP spectroscopy and GLC, the main compounds in the fraction are isomeric fluorides of the formula

 0- (CF2) i,

No., fc,

/ v%

CF, C

where with the corresponding Rf F (for), CFs (for n 2) and CsFs (for n).

Iv. Fractions 190-f-220 ° C-15.1 wt. % raw. Data from physicochemical studies show that hydrogen and C-Hc compounds are absent, but C-O-C bonds are present; the molecular weight of the main components of fraction 800 calculated by this chromatography, i.e., slightly different for the formula

0 - () u

with/

P

- CF-S

 -about

- (F2V

CF

0 CJF-Rf

where / g 1-3, with the appropriate (dl / g 3), CFs (for), (). EXAMPLE 2

fluoridation of phthalic dibutyl ether. acid. Process conditions: the electrolyte temperature is 21–22 ° C, the temperature of the return cooler is from -24 to -25 ° C, the anodic current density is 0.025 A / cm, the voltage across the electrodes is 5.85-5.95 V, the electrolyte concentration is 16 + 3% . The process is carried out periodically (with disconnection at night). For all the time the unit has been running, 1270 a-hour of electricity has been passed through the electrolyte.

The average yield of the mixture of liquid perfluoroproducts is 0.3. The resulting perfluoroproduct mixture is subjected to fractionation in a glass column. Some characteristics obtained

fractions (intermediate fractions not indicated):

I - boiling point 80-150 ° C, yield 44.9%, is a mixture of perfluoroacid fluorides;

II - boiling point 210-220 ° C, pour point 75 ° C, yield 4.8%;

1P - boiling point 230-235 ° C, pour point -64 ° C, yield 6.9%;

IV- boiling point 240-260 ° C, pour point -51 ° C, yield 15.8%;

V- boiling point 260-270 ° С, pour point -45 ° С, yield 15.9%;

VI-cube, boiling point above 270 ° С, yield 4.7%.

According to the results of analytical studies, as in Example 1, fractions II, IV, V are non-acidic perfluorinated products, resistant to acids and alkalis.

The main components of these fractions are compounds containing

R

I CF, -C-O-CF, groups,

I f

where R F or -O- (Cp2) n is the group closing in the cycle in the alcohol, or in the acid part of the molecule.

 The main components of fraction III are oxygen-containing perfluoroacid fluorides containing 18 carbon atoms in the molecule. They react easily with

alcohols to form the corresponding

esters and with water to form the corresponding acids.

Example 3. Electrochemical fluorination of trifluoroacetic acid octyl ester is carried out in a 1.8-liter electrolytic cell of a batch type. Process conditions: electrolyte temperature 21-22 ° C; temperature of the reverse refrigerator -25- -28 ° С; voltage across electrodes 5.4–5.8 v; anode current density of 0.025-0.03 initial electrolyte concentration of 20%.

The average yield of liquid perfluorinated products (raw) drained from the bottom of the cell is 0.307 g / a-hour.

The obtained raw material is subjected to fractionation in a glass column, five fractions are selected, one of which is taken in the temperature range 140-160 ° C, has a pour point below -90 ° C and according to analytical data is a mixture of perfluorinated peptidic compounds containing 10 carbon atoms and oxygen in the molecule; the yield of this fraction is 33.6% of the load.

Other fractions are mainly a mixture of fluorocarbons and perfluoroacid fluorine anhydrides containing 7-8 carbon atoms in a molecule.

Subject invention

The method of obtaining fluorocarbon fluids by electrochemical fluorination of esters in the presence of hydrogen fluoride, followed by separation of the target product in a known manner, characterized in that in order to obtain fluorocarbon fluids with higher physicochemical characteristics, the process uses esters containing 3 to 8 carbon atoms.