JPH01259188A - Production of perfluoro(3-dialkylaminopropionic acid fluoride) - Google Patents

Abstract

PURPOSE:To simply produce perfluoro(3-dialkylaminopropionic acid fluoride) in a high yield by electrolyzing 3-dialkylaminopropionic ester in liq. hydrogen fluoride. CONSTITUTION:3-Dialkylaminopropionic ester represented by general formula I (where each of R1 and R2 is alkyl, R1 and R2 may be different from each other and R is alkyl) is electrolyzed in liq. hydrogen fluoride. The alkyl groups of the compd. are converted into perfluoroalkyl groups and perfluoro(3- dialkylaminopropionic acid fluoride) represented by formula II (where each or R'1 and R'2 is perfluoroalkyl and R'1 and R'2 may be different from each other) is obtd. This product is useful as an intermediate for synthesizing a fluorine-contg. product such as a surfactant, agricultural chemicals or pharmaceuticals or as a monomer for a fluorine-contg. high molecular compd.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is useful as a synthetic intermediate for fluorine-containing products such as surfactants, agricultural chemicals, and pharmaceuticals, and fluorine-containing polymeric monomers. The present invention relates to a method for producing perfluoro(3-dialkylaminopropionic acid fluoride).

Conventional technology Perfluorocarboxylic acid fluoride is important as a raw material for, for example, surfactants, lubricating oils, water and oil repellents, and polymer compound monomers. reaction with so3 or C11So3H (French Patent No. 1,313,661, U.S. Patent No. 3,233240), oxidation reaction of perfluoroalkylvinylidene chloride (JP-A-60-188)
No. 345) is manufactured by Nato.

However, perfluorocarboxylic acid fluorides containing a nitrogen atom as a beta atom in the molecule are produced exclusively by electrolytic fluorination methods, such as perfluoro(3-dialkylaminopropionic acid fluoride) (US Pat. No. 3.47+), igi specification) is produced by electrolytically fluorinating 3-dialkylaminopropionic acid chloride hydrochloride.

However, this method requires expensive and dangerous chemicals (Cancer 5
(β-propiolactone)
It also has the disadvantage of requiring several steps and a complicated process. That is, as shown in the following reaction formula, this process first generates 3-dialkylaminopropionic acid as an intermediate compound by the reaction of a secondary amine and β-propiolactone, and then separates this as a hydrochloride. Requires multiple steps consisting of treatment with thionyl chloride or phosphorus pentachloride.

↓ aq, Bcffi (R in the formula is an alkyl group) Moreover, the yield of the 7-nomination product in this method is 3
- From diethylaminopropionic acid chloride hydrochloride,
The corresponding perfluoro(3
-ethylaminopropionic acid fluoride) is obtained.

On the other hand, in order to use a linear perfluorocarboxylic acid as a surfactant, it is preferable that the number of carbon atoms is 8 or more. (1-trifluoromethyl)perfluorocarboxylic acid] is known to have a large ability to reduce surface activity because two CF groups effectively act on the interface (U.S. Pat. No. 3,525,758). )
. From this point of view, perfluoro(3-dialkylaminopropionic acid) and its derivatives with appropriate carbon chain lengths are expected to have excellent properties as fluorine-based surfactants. Patent No. 3.47
1,481), its precursor perfluoro(3-dialkylaminopropionic acid fluoride)
The production of fluorinated products requires expensive raw materials and several steps in the synthesis of raw materials, and has drawbacks such as low yields of fluorinated products.

Therefore, the practical application of perfluoro(3-dialkylaminopropionic acid) has been extremely limited so far, and there has been a need for a method for producing perfluorocarboxylic acid fluoride simply and with good yield.

SUMMARY OF THE INVENTION The present invention aims to overcome these conventional drawbacks and provide a method for easily producing perfluoro(3-dialkylaminopropionic acid fluoride) with good yield. This was done as a.

Means to Solve the Problem The present inventors have conducted various studies to develop a method for easily producing perfluoro(3-dialkylaminopropionic acid fluoride) with high yield. 3-Dialkylaminopropionic acid esters, which can be prepared in one vessel by a Michael reaction with esters, can be electrolytically fluorinated in liquid hydrogen fluoride, surprisingly without producing any tar-like substances by-product. It was discovered that the reaction proceeded mildly and perfluoro(3-dialkylaminopropionic acid fluoride) was obtained in good yield, and based on this finding, the present invention was completed.

That is, the present invention electrolytically treats a compound represented by the general formula %() (in the formula, R1 and R2 are the same or different argyl groups, and R represents an alkyl group) in liquid hydrogen fluoride. Perfluoro(3-dialkylaminopropionic acid fluoride) represented by the general formula %() (in which R′1 and R′2 each represent the same or different perfluoroalkyl group), which is characterized by A manufacturing method is provided.

The present invention will be explained in detail below.

The 3-alkylaminopropionic acid ester used as a raw material in the method of the present invention can also be synthesized by the reaction of a dialkylamine and a 3-bromopropionic acid ester.
[Journal of American Chemical Industry (J, Amer, Ch.
em, Soc, ) J Volume 81, Page 3618 (1
959)], it can be obtained at low cost and in high yield by the Michael reaction of the corresponding argyl amine and acrylic ester. Among the acrylic esters, methyl acrylate is particularly preferred.

In the electrolytic fluorination reaction in the method of the present invention, an electrolytic cell conventionally used in the conventional electrolytic fluorination reaction can be used. In addition, the reaction is carried out in liquid hydrogen heptadide, and at this time, the concentration of the raw material 3-dialkylaminopropionic acid ester is not practical if it is too low, and tar-like substances are likely to be generated if it is too high, so it is usually It is selected in the range of 1 to 80% by weight, preferably 3 to 20% by weight. The current density is usually 0.01-10 A/dm2, preferably 0.1-
It is selected within the range of 5A/dm2. As this current density increases, the electrolytic voltage tends to increase, and on the other hand, as the current density increases, hydrogen fluoride tends to escape. The reaction temperature is usually -20~
The temperature is selected to be 50°C, preferably in the range of -10 to 2°C.

=7- This electrolytic reaction is usually carried out at normal pressure, or can be carried out under increased pressure if desired. When the reaction is carried out under pressure, the boiling point of hydrogen fluoride increases, which has the advantage of easing cooling of the reaction system. Moreover, either a continuous method or a hatch method can be used to carry out the reaction.

When this is carried out using the hatch method, the electrolysis time to complete the reaction depends on the current density and the amount of raw materials, but it is generally preferable to adjust it to a range that provides 80 to 200% of the theoretical amount of electricity. .

These electrolytic fluorination conditions usually vary depending on the type of raw material used, but may be appropriately selected in consideration of the yield of the desired product and current efficiency.

In addition, in order to efficiently carry out electrolytic hydrogenation and improve the yield of the desired product, it is desirable to stir the electrolyte during the reaction, and for this purpose, mechanical forced stirring or introduction of inert dregs is recommended. A stirring method can be used.

As a result of the fluorination reaction, the cleaved low-boiling products are either flowed out of the electrolytic cell along with other generated residues, or most of the target perfluoro(3-alkylaminopropionic acid fluorite) is removed from the electrolytic cell. Since it remains in the liquid hydrogen fluoride and does not dissolve in the liquid hydrogen fluoride, it separates and forms two layers, so it can be easily taken out after the electrolysis is completed.

Through such electrolytic fluorination reaction, the above-mentioned general II (II)
), the corresponding perfluoro(3-dialkylaminopropionic acid fluoride) represented by the above-mentioned general 2(I) can be obtained.

That is, R1 and R2 in general formula (II) are R'1 and R'2 of the corresponding general formula (I) as shown in the usual method.
is converted to

C, R2, -I C, F2. +1/
/ -N → -N \ \ Cm112m++ CmF2m++(n
and m is an integer of 1 to 4) In this way, perfluoro(3-dialkylaminopropionic acid fluoride) having a perfluoroalkyl group corresponding to the alkyl group of the starting compound is obtained.

Effects of the Invention According to the method of the present invention, perfluoro(3-dialkylaminopropionic acid fluoride) can be obtained in good yield by electrolytically converting easily available 3-dialkylaminopropionic acid ester. This product is useful, for example, as a synthetic intermediate for fluorine-containing products such as surfactants, agricultural chemicals, and pharmaceuticals, and monomers for fluorine-containing polymer compounds.

For example, perfluoro(3-dialkylaminopropion r6.) derived from the target compound of the present invention is useful as an excellent surfactant in itself, and its ability to lower the surface tension in an aqueous solution of its thorium salt is It is comparable to the industrially important sthorium perfluorooctanoate salt and is extremely useful.

EXAMPLES The present invention will now be explained in more detail by way of examples.
The present invention is not limited to these examples in any way.

The electrolytic cell was made of Monel metal, and the electrodes were made of 7 anodes and 8 cathodes made of Ninkel plate, arranged alternately with an inter-electrode distance of 2 mm, with an effective anode area of 7,54 mm.
m2 was used.

Example 1 In a 1A three-neck flask equipped with a dropping funnel and a stirrer, 86.0 g of methyl acrylate and 100 m of methanol were added.
80.3 g of diethylamine was added from a dropping funnel over about 30 minutes while occasionally cooling on ice, and the mixture was further stirred at room temperature for 2 hours, and then refluxed for 2 hours. The reaction mixture was then distilled to give 146 methyl 3-diethylamine propionate (boiling point 103-1040 C/4.8 Lo+r).
．． 4Li (yield 92.1%) was obtained.

Next, 4.50 Inl of anhydrous heptanohydric acid was introduced into the electrolytic cell, and trace amounts of impurities were removed by preliminary electrolysis.

Next, 40.99 ml of methyl 3-diethylamine propionate produced as described above was added to the electrolytic cell, and the anode current density was 3.3 A74 m2, the bath temperature was 7 to 9°C, the electrolytic voltage was 7.2 to 7.4 V, and the electrolysis rate was 231 Ahr. Electrolysis was performed.

The final electrolysis voltage is 8. Reached OV. The generated gas was passed through a sodium fluoride tube to remove accompanying hydrogen fluoride, and then collected in a trap cooled to -78°C.
Fluorocarbon mixture] 4,79 was obtained. Also,
After electrolysis, open the drain cock at the bottom of the electrolytic cell and remove the high boiling point fluorocarbon 33.49 as the cell drain compound.
I pulled it out.

Next, add a small amount of pelleted molecular sieve 4 to these.
After adding A to remove the remaining hydrogen fluoride, cass chromatography [carrier: ■e, liquid phase: 1,6-
His(1,1,12-trihydroperfluoro-1-denruoxane/)hexane, carrier: 60-80 mesh chromosorb PAW), IR, "F NMRlMass, elemental analysis (carbon), etc. revealed that perfluoro(3-diethylamine propionic acid fluoride) is 3
o, cig (yield 30.1%) was obtained.

This was identified as a methyl ester derived directly from it. This methyl ester has a boiling point of 13
g-139℃, nD”13090, d, 2゜1.707
7, and its infrared absorption spectrum is 1789 cm-'
showed a characteristic absorption based on -COOMe.

Example 2 The raw material methyl 3-(di-n-propylamine)propionate (boiling point 81-84°C/81 orr) was the same as Example 1.
It was produced in the same manner as (yield 905%).

Methyl 3-(so n-propylamino)propionate 4
0, 19, the electrolytic voltage is 60 to 6.8V, and 279
Electrolytic fluorination was performed under the same conditions and method as in Example 1, except that Ahr electrolysis was performed. After the electrolysis is completed, open the train cock at the bottom of the electrolytic cell and pour out the fluorocarbon mixture 53.
．． I got 99. Also, 6.9 g of fluorocarbon mixture was collected in the cold trap. When these were treated and analyzed in the same manner as in Example 1, it was found that perfluoro[3-
(di-n-furopylamino)propionic acid fluoride)
27.3 g (yield 25.5%) was obtained. The physical properties of the methyl ester derived therefrom have a boiling point of 160-162
'O,n[]''1.'3103,d,''1.7607, and its infrared absorption spectrum showed a characteristic absorption 1789cm-' based on -COOMe.

Reference Example] From the perfluoro(3-diethylaminoprobionic acid fluoride) obtained in Example 1, the corresponding perfluoro(3-diethylaminoprobionic acid fluoride)
3-diethylaminopropionic acid) was carried out as follows.

As a raw material, a celludrain compound obtained by electrolytic fluorination of methyl 3-diethylaminopropionate was used as it was.

First, add 50ml of water to a 200mM three-necked flask, stir with a magnetic stirrer, and add 27.1g of the above cellutoline compound (into this, 21.4g of perfluoro(3-diethylaminopropionic acid fluoro-1-)). was slowly added from the dropping funnel. Immediate hydrolysis reaction took place and the solution became cream-like. After stirring at room temperature for about 30 minutes, it was extracted with ether, and the extract was washed with Mg5O and dried overnight. After that, distillation is performed to reduce the boiling point to 104
Colorless and transparent perfluoro(3-diethylaminopropionic acid) at ~105°C/4,4+,orr 21.49
(yield 89.2%) was obtained.

Table 1 shows the surface tension of an aqueous solution (25°C) of this sodium salt.

Table 1 Reference Example 2 Perfluoro[3-(sea n-
Perfluoro(3-(so-n-propylamine)propionic acid) (boiling point 118-124°O/52) orr) was synthesized from propylamino)propionic acid fluoride (yield 767%).

Table 2 shows the surface tension of this aqueous solution (25°C) of thorium salt.

In Table 2, attached drawings show perfluoro(3-diethylaminopropionic acid sodium salt), perfluoro[3-(di-propylamine)propionate sodium salt], and perfluoro(3-diethylaminopropionate sodium salt) derived from the compound of the present invention. - dimethylamine propionate sodium salt) is a graph showing the relationship between concentration and surface tension of perfluorooctanoic acid sodium salt for comparison.

[Brief explanation of the drawing]

The drawing is a graph showing the surfactant effect of compounds derived from the compounds of the present invention.・perfluoro(3-dimethyl70:perfluoro(3-diethyl70:perfluorofucunate)△:perfluoro[3-(di-n-sodium salt)'minopropio/acid sodium salt)'minopropio/acid sodium salt Salt) Thorium salt Propylamine) Brobionoic acid

Claims (1)

[Claims] 1. A compound represented by the general formula ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (II) (R_1 and R_2 in the formula each represent the same or different alkyl group, and R represents an alkyl group) There are general formulas, mathematical formulas, chemical formulas, tables, etc. that are characterized by electrolytic treatment in hydrogen fluoride. (I) (R'_1 and R'_2 in the formula represent the same or different perfluoroalkyl groups, respectively. ) A method for producing perfluoro(3-dialkylaminopropionic acid fluoride) represented by: