NO153965B - PROCEDURE FOR PERFLUORING POLYCYCLIC HYDROCARBONES. - Google Patents

Description

The present invention relates to a method for the perfluorination of non-aromatic polycyclic hydrocarbons using a three-stage reaction which effectively eliminates the formation of unwanted by-products.

In US patent no. 3,641,167, as well as application no. 647,944 (January 12, 1976), a one-step process for the production of perfluoroalkyladamantanes is shown. Recently obtained data using new analytical techniques have shown that under the reaction conditions used there, namely the use of CoF^ and high temperature, results in a breakdown of the non-fluorinated cyclic structure which leads to the formation of ring-opened products.

According to the present invention, it has now been found that polycyclic hydrocarbons can be perfluorinated without essentially any breakdown of the cyclic structure, by the method indicated under the characterizing part of claim 1.

The starting compounds used in this improved per-fluorination process include non-aromatic polycyclic hydrocarbons such as alkyladamantanes, as described in US Patent No. 3,641,167 containing 11 - 30 carbon atoms, preferably 12 - 14 carbon atoms, such as 1,3-dimethylada- mantane, 1,3,5-trimethyladamantane, 1-ethyladamantane, 1-methyl-adamantane, l-ethyl-3-methyladamantane, l-ethyl-3,5-dimethyladamantane etc., endo- and exo-tetrahydrocyclopentadiene, methane- decalins such as 1,4-methanedecalin or 1,4,5,8-dimetanedecalin, hydrogenated pinane, camphane, bicyclooctanes, bicyclononanes etc. When these compounds are treated according to the present method, the corresponding perfluorinated polycyclic compounds are obtained in high yield and high purity, where at least 95% of the hydrogen atoms, preferably 97% - 100% of the hydrogen atoms, are replaced by fluorine atoms. In the present method, a conversion of the starting material to the corresponding perfluorinated compound will be at least 50% or usually 90% or more. These perfluorinated compounds are useful in a number of different industrial and pharmaceutical applications. The fluorinated alkyl adamantanes are, for example, useful as gas turbine coolants, dielectric coolants for transformers, generators, etc. as well as components in synthetic blood mixtures, perfusion media etc. biological applications. The perfluorinated cyclic materials are also useful as working media in heat pipes and in "Rankin" cycle engines.

In the present method for the perfluorination of non-toxic polycyclic hydrocarbons, it has been found for the partial fluorination that an incorporation of 3 - 6 fluorine atoms in the hydrocarbon will stabilize the material before the harsher conditions used in the complete fluorination, for example with CoF^.

In general, during the first partial fluorination step, the above-mentioned fluorinating agents can be reacted directly with the polycyclic hydrocarbons as such, or if desired with their partially chlorinated or brominated derivatives. However, an exception to this reaction with these compounds is with SF4 or dialkylaminosulfur fluorides, in which case the cyclic starting material must first be carbonylated before it can be satisfactorily reacted with SF4 or dialkylaminosulfur fluoride. E.g. in the case of alkyladamantanes, these compounds must first be converted to their corresponding ketones, aldehydes, acids or hydroxy derivatives before they will react satisfactorily with SF4 or dialkyl-aminosulfur compounds.

Examples of methods for obtaining these adamantyl carbonyl derivatives can for example be found in US patents no. 3,356,740 and 3,356,471 (adamantyl dicarboxylic acids), US patents 3,383,424, 3,356,718 and 3,356,709 (adamantyl dihydroxides and dicarboxylic acids ). Other corresponding reactions will be understood by a person skilled in the art.

In the same way, such carbonylated polycyclic starting materials can be prepared according to the known techniques.

It will thus be understood from the foregoing that a general mention of the partial (i.e. first stage) fluorination of the polycyclic starting materials is in all cases also intended to include their carbonyl derivatives, when SF^ or dialkylaminosulfur fluorides are used as fluorinating agent.

In addition to the use of carbonyl derivatives of the cyclic compounds to be perfluorinated, when SF^, one can use analogous known alcohol derivatives of these compounds when HF or the HF-pyridine complex is used as the partial fluorinating agent, and chlorinated and brominated derivatives are used when SbF^ are used.

One can also react cyclic dienes such as 1,3-cyclohexadiene with fluoroolefins such as hexafluoropropene in a Diels-Alder type reaction to afford partially fluorinated polycyclic hydrocarbons, as described in more detail below. These materials can also be perfluorinated according to the present invention.

The above-mentioned Diels-Alder reaction products are thus intended to be covered by the general definition of the partially fluorinated polycyclic hydrocarbons which can be perfluorinated, for example with CoF 2 , as described above.

It will thus be understood from the foregoing that it falls within the scope of the present invention to completely fluorinate a partially fluorinated, and thus stabilized, cyclic hydrocarbon regardless of how it is produced.

The degree of fluorination necessary to provide ring structure stability for the polycyclic materials before these are reacted with strong fluorinating agents, such as CoF^

in the second and third steps of the present method, is not critical, but should include replacement of 3 - 6 hydro-

gene atoms with fluorine atoms and up to as much as 50% replacement of such hydrogen by fluorine. The localization of these fluorine atoms can either be in the nucleus or in the side chain of the hydrocarbon molecule or both. It will therefore be understood that the product obtained in the first fluorination step may comprise a single product or a mixture of partially fluorinated materials, depending on the fluorinating agent used. This product should, before being brought into contact with CoF^ etc. in the subsequent step, first separated from the first fluorinating agent, preferably by distillation.

In the second step of the present method, the aim is to achieve as high a degree of fluorination as possible without breaking down the compound's ring structure. The result of this fluorination step is to impart the greatest possible stability to the partially fluorinated polycyclic material so that in the last step essentially 100% perfluorination can be achieved under much more stringent reaction conditions without ring cleavage by-products being formed. The high degree of fluorination in the second stage, which generally does not differ from perfluorination by more than 5-25%, is easily achieved by contacting the partially fluorinated hydrocarbon mixture with CoF^ in the vapor phase (by preheating) at a moderate feed rate at a temperature of the area just above the boiling point of the added material to approx. 50^C above its boiling point. Preferably one is used. multi-zone reactor with temperatures varying from just above the boiling point to 50° above this. As the reaction is exothermic, temperatures should be controlled to lie within these ranges to avoid breakdown of the molecules.

In the final step, which likewise takes place in the vapor phase, and which comprises recycling the highly fluorinated product from the CoF^ reaction back to the same reactor, which this time is heated to a significantly higher temperature, preferably lOO^C more above the thermally graded reactor ,

to achieve substantially complete perfluorination to

to give yields of 50 - 95%, calculated on the quantity of the original added material.

The perfluorinated product is then preferably cooled to temperatures in the range -80^ - 0^C by passing it again

about several cooled traps as it is removed from the reactor to collect not only the desired end product but also HF and other gaseous products.

The invention is illustrated by the following examples.

The following four examples show the preparation of partially fluorinated adamantanes, which are then perfluorinated according to the present method.

Example 1

Adamantane dicarboxylic acid (22.4 g, 0.1 mol) and SF^ (27.0

g, 25% excess) was heated in a "hook" bomb for 24 hours at 110°C. The contents of the pressure vessel were cooled, extracted with CCl 2 , filtered and the CCl 2 evaporated. The residue obtained consisted of 21.8 g of bistrifluoromethyl (80% yield).

Example 2

2-adamantanone (15.0 g, 0.1 mol) and SF^ (13 g, 25% excess) were heated as indicated in Example 1. The product obtained was worked up as described in Example 1 and 12 was obtained, 9 g of 2,2-difluoroadamantane (75% yield).

Example 3

5,7-Dimethyl-1,3-adamantane-dicarboxylic acid (25.2 g 0.1) and SF^ (27.0 g 25% excess) were heated and worked up as indicated in Example 1 and 18 g were obtained 3,5-dimethyl-5,7-bis(trifluoromethyl)-adamantane (yield 60%).

Example 4

Bistrifluoromethyladamantane (24 mL, 33.67 g, 0.123 mol) from Example 1 was introduced into a preheater at a rate of 0.247 mL/min. The preheater temperature was 250 °C and the CoF reactor temperature was graded from 250 0°C in zone 1 to 300°C in zone 4. The added product was held at 225°C. After all the hydrocarbon had been passed through the reactor, it was flushed with nitrogen for 3.25 hours. The crude product obtained weighed 46.0 g. This material was washed with water until the pH of the water was 5. This material from the second step was dried over molecular sieves overnight after which 45.84 g was reintroduced at a rate of 0.764 ml/min. to the reactor which was graded from 275°C in zone 1 to 380°C in zone 4 in the final final stage. The reactor was flushed with nitrogen for 4 hours before removing the product receiver assembly containing 47.8 g of fluorocarbon, 75% material balance. Gas chromatography analysis showed that the product consisted of 90% perfluoro-1,3-dimethyl-adamantane, which

19

was confirmed with mass spectrography and FNMR.

A similar experiment was carried out with 1,3-bis(trifluoromethyl)

-5,7-dimethyladamantane and a 55% yield of perfluorotetramethyladamantane was obtained. In a similar way, 2,2-difluoroadamantane and 3,5-dimethyl-5,7-bis(trifluoromethyl)-adamantane obtained according to examples 2 and 3 were reacted with CoF^ according to the above-described method according to example 5 and man obtained the corresponding perfluoroadamantes with high yield and purity.

Example 5

Exo-tetrahydrocyclopentadiene (25 mL, 24.15 g, 0.1776 mol) was introduced into the preheater at a rate of 0.494 mL/min, the temperature of which was 225°C and the CoF reactor temperature

0 0

was graduated from 200 C in zone 1 to 250 C in zone 4. The added product was kept at 225°C. After all the hydrocarbon had been passed through the reactor, it was flushed with nitrogen for 3.25 hours. The crude product obtained weighed 63.5 g and was washed until the pH of the wash water was 5.

The material from the second stage was dried over molecular sieves overnight, after which 55.84 g was reintroduced at a rate of 0.764 ml/min to the reactor which was graded from 300°C in zone 1 to 375°C in zone 4 for the final final stage. The reactor was flushed with nitrogen for 4 hours before the product receiver was removed which contained 60.8 g of fluorocarbon; 87% material balance calculated on 24.15 g THDCP added. Gas chromatography analysis showed that the product contained 40% endo- and exo-perfluoro-tetrahydrocyclopentadiene, 45% perfluorobicyclo (3,5,0)-decane and approx. 15% unknown fluorocarbons.

Example 6

Exo-tetrahydrocyclopentadiene (35 g) is added slowly to a suspension of MnF₂ (450 g) in perfluoro-(1-methyl)-decalin solvent. After all the hydrocarbon has been added, the mixture is heated to 200°C and stirred rapidly for 24

hours. The product is extracted with "Freon 113" and distilled to remove both "Freon 113" and perfluoro-(1-methyl)-decalin. The distillation residue consisted of partially fluorinated tetrahydrodicyclopentadiene in which the average molecule contained approx. 7 fluorine atoms, i.e. C^qH^F^.

The partially fluorinated tetrahydrodicyclopentadiene thus obtained was then perfluorinated with CoF^ according to the procedure in example 5, where essentially pure exo- and endo-perfluorotetrahydrodicyclopentadiene was obtained in high yield, and which was essentially free of those in example 6 said by-products.

Example 7

By following the procedures according to example 6, but instead of using partially fluorinated camphane, hydrogenated pinane, 1,4-methanedecalin or 1,4,5,8-dimetanedecalin instead of partially fluorinated tetrahydrocyclopentadiene, the corresponding perfluorinated cyclocarbons were obtained in high yield, and essentially free of cleaved ring-opened by-products.

Example 8

As previously indicated, fluoroolefins and acetylenes readily undergo Diels-Alder type reactions and act as dienoolefins in 1,4-cycloaddition reactions and their reactivity towards dienes is generally higher than that of their corresponding hydrocarbon analogues. The following examples show the preparation of partially fluorinated cyclocarbons which can be completely fluorinated according to the method according to example 4 to give perfluorinated cyclocarbons in high yield and essentially free of ring-opened biproducts: A. 1,3-cyclohexadiene (1 mol) is reacted with a 25% molar excess of hexafluoropropene for 24 hours at approx. 150°C

to give 2-(trifluoromethyl)-2,3,3-trifluoro-bicyclo-(2,2,2)-octane. Hydrogenation over rhodium yields 2-(trifluoromethyl)-2,3,3-trifluorobicyclo-(2,2,2)-octane.

B. In the same way, reaction of cyclopentadiene with hexafluoro-but-2-yne at 100°C for 24 hours gives 2,3-bis-(tri-fluoromethyl)-bicyclo-(2,2,1)-heptadiene as by hydrogenation over platinum gives 2,3-bis(trifluoromethyl)bicyclo-(2,2,1)-heptane. C. In the same way, reaction of octafluoro-but-2-ene with cycloheptadiene will give 2,3-difluoro-2,3-bis(trifluoromethyl)-bi-cyclo-( 2 , 2 , 1 )-heptane which after hydrogenation over ruthenium gives 2,3-bis(trifluoromethyl)bicyclo-(2,2,1)-heptane.

Example 9

Norbornadiene (1 mole) and a 25% molar excess of hexafluorocyclopentadiene are heated for 24 hours at 100°C to give

which after treatment with CoF^ according to the method according to example 4 gives a very pure perfluoro 1,4,5,8-dimetanedecalin.

Claims (2)

1. Procedure for perfluorination of non-aromatics. polycyclic hydrocarbons, characterized by (1) partially fluorinating the polycyclic hydrocarbon by bringing it into contact in a first reaction zone with a fluorinating agent such as HF, HF-pyridine, AgF2, MnF^, SF4-SbFj., KCoF^ or fluoroolefins, in the liquid phase under conditions which are sufficient to provide no more than 50% fluorination relative to perfluorination, (2) then further fluorinating the partially fluorinated polycyclic hydrocarbon in the vapor phase in a second reaction zone with CoF, at a temperature not exceeding the boiling point of the fluorinated material by more than 50°C, to provide a highly fluorinated material having a degree of fluorination corresponding to no more than 75. - 95% in relation to perfluorination, and (3a) recovering and recycling the highly fluorinated material to the second reaction zone and again bringing it into contact with the same CoF.. in the vapor phase at a temperature 100°C higher than that first used in step (2) above to give a substantially perfluorinated polycyclocarbon, or (3b) recovering the highly fluorinated material from the second reaction zone, transporting it into a further zone and bringing it into contact with CoF, in the vapor phase at a temperature 100°C higher than that used in step (2) to give essentially perfluorinated polycyclocarbon. 2. Method according to claim 1, characterized in that an alkyladamantane with 11-30 carbon atoms is used as the polycyclic hydrocarbon.