DE1668546C3 - Process for the preparation of perfluoroacrylic acid chloride - Google Patents

Description

; - '--- contact compound is used, it can be applied to the glass

or quartz beads, small glass or quartz tube

iS bits, metal shavings, metal shavings or the like.

* Peiflupacrylic acid fluoride CFI - CF ^ COF would pass. The pyrolysis is expediently carried out under

t _r 'i bister by reacting perfluoroally iodide with reduced pressure in the order of 1 to

'- Mercury nitrate produced (Journal of Oranic 250 mm Hg carried out for too long contact time

Chemistry, Vol. 28 [1963], pp. 1728-1730). to avoid; but this is not essential. The object of the invention is to provide a method for ao The hydrolysis can rather also at Attno- Provide at which one can be carried out by the technically spherical pressure, especially if

easily available perfluoropropene can go out. a stream of inert gas (e.g. nitrogen or argot)

The invention relates to a method for used as a carrier and diluent. the Production of perfluoroacrylic acid fluid, which generally has a residence time in the reaction space

one a-hydrotetrafluoropropionic anhydride in Ge 25 in the range of 0.5 to 10 seconds. That and that

in the presence of an inert contact mass or vaporous reaction space exiting from the hot boron

phosphate or alkali fluoride as a catalyst for temperature pyrolysis product is in an arrangement of cooling

Temperatures of at least 350 ⁰ C condensed under practical receivers and then through fractionated

Pyrolyzed anhydrous conditions. Worked up distillation. When fractionating

The reaction takes place according to the following equation: Recovered unchanged starting material can

chung: be circulated.

One can use the "-hydrotetrafluoropropionic acid an-

(CF ₈ CHFCO) ₄ O hydride also in a closed reaction vessel

-> CF ₁ = CFCOF + CF ₃ CHFCOOH under which is derived from the starting material and the

35 reaction products from self-developing pressure

It can also be different amounts of or under an additional inert gas pressure for a Form by-products, such as a-HydrotetraÜuorpro- a certain time to the required temperature

pionic acid fluoride, trifluoroethylene, carbon monoxide and heat.

Trifluoroacetaldenyd, the latter in the crude. Boron phosphate, also known as a pyrolysis product in the form of polymers, can contain boron orthophosphate (BPO ₄ ), or an alkali fluoride, such as sodium, potassium or cesium fluoride. It is surprising that these Conversion to Per- can also be used in anhydrous form. fluoroacrylic acid fluoride, since the pyrolysis of The last-mentioned catalyst offers the special carboxylic acid anhydrides in general to the formation of their advantage that the resulting perfluoroacrylic acid leads to ketenes: (Hanford & Sauer, "Pre- 45 acids ¹ uorid not with a-hydrotetrafluorpropionic acid separation of ketenes and ketenes dimers" , Organic fluoride is contaminated, the latter as Reactions, Volume III, Chapter 3, pp. 108 to 140 [1946]). A by-product is formed when the reaction is carried out without the α-hydrotetrafluoropropionic acid, which is generally used as a starting catalyst or in the presence of boron phosphate in the process according to the invention. The α-hydroanhydride can be separated off economically from perfluoropropionic acid fluoride from the perfluoroacrylic fluoropropene. For this purpose, acid fluoride requires a chromatographic addition. Α-hydrotetrafluoropropionic acid, e.g. B. after action. When using alkali fluorides, the 3-step process of US Pat. No. 28,62024 avoids this separation.

made from perfluoropropene The acid The degree of fineness of the catalyst is insignificant.

is then borrowed by treatment with phosphorus pentoxide 55; however, particle sizes are most advantageous

at moderately elevated temperatures to the anhydride between about O ₁ S and 5 mm. The amount of in

dehydrated. A typical manufacturing process of a static or flowing reaction system at-

for the anhydride, the following applies: turned catalyst is not decisive. she

A mixture of 37Og «-hydrotetrafluoropropion- can be of small amounts, e.g. 0. Of mole per mole

acid and 370 g of phosphorus pentoxide is in a 60 "-Hydrotetrafluorpropionsäuiieanhydrid, up to cr-

Reflux condenser and drying tube equipped KoI- considerable molar excesses vary * the z. B.

beil heated on the steam bath for 16 hours Then applied when the catalyst is the

a vacuum is applied, and the volatile substances form the only contact mass ia the flow system

are in a ^{template cooled to -8O 0} C con- The pyrolytic decomposition of the a-hydrotetrafloor-

condensed. By distilling this propionic anhydride twice to give perfluoroacrylic acid fluoride

Düktes over some phosphorus pentoxide one gets 274 g requires temperatures of «hM» »* ™ * 350 ⁰ C Die

-Hydrotetrafluoropropionic anhydride; Kp. = 137 Choice of the suitable Realktionstemperator depends

to 138 ⁰ C. The nuclear magnetic proton resonance largely depends on the catalysts used.

In the presence of boron phosphate, the BU begins The perfluoroacrylic acid fluoride is

formation of perfluoroacrylic acid fluoride at 3SO ⁰ C, and appropriate fraction by gas phase chromatography

the preferred temperature range is separated in this. The mixture is at room temperature

Trap at 375 to 500 ⁰ C in the presence of alkali passed through a 7.3 m long, 187 cm wide column,

fluoride begins the implementation at about 400 ⁰ C, 5 which is done with technical Sfliconöl on brick pieces

and the preferred temperature range is 500 fills. For each injection a sample of 0.8 ml

up to 600 ⁰ C. In the absence of catalysts, the hydrotetrafluoropropionic acid fluoride is used

the formation of the perfluoroacrylic acid fluoride flows in about 23.7 minutes, the perfluoroacrylic acid fluoride

525 ° C, and the preferred temperatures are in 29.8 minutes. Pure perfluoroacrylic acid fluoride

Range from 550 to 650 ⁰ C. In all cases, it is io boils at 25.5 ° C; VgL Tarrant and Savory,

if desired also at much higher temperatures, a. a. O. The ultrared spectrum shows absorption

z. B. up to 800 ⁰ C, work. bound at 5.36μ (COF) and 5.70μ (CF = CF ₂ ). The

Perfluoroacrylic acid fluoride is a commercially nuclear magnetic F ¹⁹ resonance spectrum that is correct

useful chemical compound. It is matched by both that of Ramey and B r e y in

its acid fluoride function as well as through its un- 15 "Journal of Physical Chemistry", Volume 40, 1063,

saturated bond very reactive and can p. 2349, is indicated

therefore as an intermediate product in the manufacture of many examples 2

valuable products are used. Furthermore, ^p

Perfluoroacrylic acid fluoride surprising dyeing In this example, the device and

and surface-modifying effects on a »o by the method of Example 1 with the following

Number of textile fibers. If z. B. Fibers worked out of modifications: a) There is no catalyst Polyacrylonitrile or copolymers of the used; the boron phosphate in the middle part of the Acrylic acid nitrile for 1 hour at 100 ^° C. in a reaction tube is passed through pieces of quartz tube

closed vessel replaced with perfluoroacrylic acid fluoride vapor 9 mm in diameter and 6 mm in length; b) the

be treated, they take on a beige color. 35 The temperature in the reaction space is 577 to 600 ° C.

Silk fibers are treated with 100 g of a-hydrotetrafluoropropionic anhydride.

light yellow, wool fibers dyed bright yellow. These dyed at this temperature over the course of 2 hours

Colorings are resistant and against the flow through the pipe. The low-boiling pro- Wash with soap or detergent resistant. products (boiling points below 35 ° Q are derived from the in Under the same conditions, polyamide fibers 30 of the cooling blanket suffer condensate collected,

a surface change by becoming a dull and the high-boiling material becomes in the cycle

adopt a similar structure. guided. After four passes through the reaction

The whole reaction should take place under practically a water pipe to obtain 19 g of material with a boiling point

free conditions are carried out, since both of about 25 ° C, that of a mixture of about

the starting material and the reaction product 35 equal parts perfluoroacrylic acid fluoride and <x-Hy-

are sensitive to water. drotetrafluoropropionic acid fluoride. This mixture can be by gas phase chromatography in

Example 1 ^seme ingredients decompose.

50 g «-hydrotetrafluoropropionic anhydride are 40 Example 3

slowly from the dropping funnel into the upper part

a vertical tube made of high-silica glass in place of boron phosphate containing sodium fluoride spheres

2.5 cm inside width and 50 cm in length. Diameters of about 3 mm; the highest response

The pipe is in its 30 cm long middle part with temperature is 550 ° C and the pressure in that Boron phosphate (particle diameter about 1.2 to 45 reaction tube about 10 mm Hg (since the initial

2.3 mm) and the pressure in this section is 4 mm Hg, this indicates the formation

an electric furnace ^{heated to 400 0} C The tube of carbon monoxide in the reaction). From 50 g

hydrotetrafluoropropionic anhydride is obtained via a template cooled with liquid nitrogen

connected to a vacuum pump, which increases the pressure in this way in the cooling reservoir a condensate, which at

reduced to 1 to 5 mm Hg in the tube. At the end of the distillation, 16 g of perfluoroacrylic acid fluoride (b.p.

The one-hour reaction will give the in the cooling pre- = 25 ° C) and 4 g of higher-boiling substances. The

position of the collected condensate at atmospheric pressure Perfluoroacrylic acid fluoride is chemically

distilled. This gives 3 g below 0 ⁰ C boiling table F ^ -Resonanzspektrum identified. It contains

Material (mainly trifluoroethylene); 18.4 g main- no detectable amounts of a-hydrotetrafluoro-

material boiling at 25 ° C, which consists of the same 55 propionic acid fluoride.

Share perfluoroacrylic acid fluoride and a-hydrotetra- If the same procedure at a maximum

fluoropropionic acid fluoride, and 23.4 g higher temperature of about 650 ° C is obtained

boiling material, which is mainly made up of -hydroman from 50 g starting material 10 g does not contaminate

tetrafluoropropionic acid and approximately unreacted purified perfluoroacrylic acid fluoride and 3 g higher-

Anhvdrid exists. 60 boiling substances.

Claims (1)

-j spectrum of the product shows that there are about 4 Gswidils- ^s ( i claim: percent unreacted a-hydrotetrafluoropropionic SV _{contains v} acid. - * \ * Process for the production of perfluoroacrylic- Pyrolysis is most advantageous dark _ ;. acid fluoride, characterized 5, by placing the anhydride in liquid Fenn p * · ■ 'that a-hydrotetrafluprpropionic anhydride or in vapor form in one of the reaction temperatures introduced in the presence of an inert contact mass and / or temperature maintained reaction space, the ge of boron phosphate or alkali metal fluoride as the catalyst - if necessary the catalyst, an inert contact t 'sator may contain bulk or both at temperatures of at least 350 ° C. As a reaction space t under substantially anhydrous conditions py io be suitably used a tube made of an inert rolyzed. Material such as heat-resistant glass, quartz, ceramic . mix materials, steel, nickel, platinum, etc. Warning one