US3525758A

US3525758A - Preparation of fluorine-containing carboxylic acids

Info

Publication number: US3525758A
Application number: US430698A
Authority: US
Inventors: Atsuo Katsushima; Iwao Hisamoto; Masayuki Nagai
Original assignee: Daikin Industries Ltd
Current assignee: Daikin Industries Ltd
Priority date: 1964-02-08
Filing date: 1965-02-05
Publication date: 1970-08-25
Anticipated expiration: 1987-08-25
Also published as: DE1518699A1; GB1092141A

Description

AUS 25, 1970 ATsUoKATsusx-HMA ETAL 3,525,758

PREPARATION OF FLUORINE-CONTAINING CABOXYLIC ACIDS Filed Feb. 5, 1965 /A/ nauseas Mew/A (2.51)

Lon/E/I/THHTIo/v {mole/f) H WH H 6.00 Q FLE /G\b)4 @EEZ Erb l \/4.J .d c ABC Cl n/vm/Tfrfmo/u (male/f) H m 6H 4 @m @6 F@ 6F \/M3 RFJP CEU DE United States Patent Oce 3,525,758 Patented Aug. 25, 1970 Int. Cl. C07c 53/34 U.S. Cl. 260-408 r 4 Claims ABSTRACT F THE DISCLOSURE Aliphatic w,w di-(triiluoromethyl) peruorocarboxylic acids and salts, esters and amides thereof. The acids have the structural formula:

wherein n is 2 to 21.

Methods for preparing such compounds by oxidizing compounds having the following structural formulae:

wherein Y is Br or l;

X1 and X2 are each H, F, C1, Br or I, but only one of X1 and X2 may be F;

X3 and X4 are each H, F, C1, Br, l, OH, R, OR, OCR, OOCR, ROH, COOR, or COOH, R being an alkyl group having 1 to 3 carbon atoms;

X5 and X6 are each H, Cl, Br or I, but only one of X5 and X6 may be H;

m is an integer from 1 to 10; and

p is an integer from 2 to 3.

The acids and the derivatives have improved surface tension properties.

This invention relates to ilumine-containing compounds. More particularly, the invention pertains to the aliphatic w,wdi(triuoromethyl)-peruorocarboxylic acids having a group of the formula attached to a terminal position. The invention further relates to the method of manufacturing said carboxylic acids.

The experience and research of the present inventors in the production of aliphatic peruorocarboxylic acids and the properties thereof have shown that there are radical differences between the straight-chain peruorocarboxylic acids and the branched-chain pertluorocarboxylic acids having a group of the formula bonded to a terminal position, and that the latter excell much more compounds in utility than the former.

It is accordingly one object of this invention to provide a series of useful aliphatic w,u-di(trifluoromethyl)per fluorocarboxylic acids having as a side chain a triuoromethyl group attached to a terminal position.

Another object of the invention is to provide aliphatic uw di- (triuorornethyl) peruorocarboxylic acids displaying a marked ability in liquid media to decrease the surface tension of said media to a considerable extent.

A further object of the invention is to provide aliphatic w,wdi(triuoromethyl)-peruorocarboxylic acids, the surface tension of which is no more than, 18 dynes/cm. in the vicinity of the critical micelle concentration in aqueous media.

A still further object of the invention is to provide aliphatic was di (triuoromethyl) peruorocarboxylic acids which can be profitably employed as raw materials for the manufacture of useful Water and oil repellants and surface active agents.

A still further object of the invention is to provide aliphatic w,wdi(uoromethyl)-peruorocarboxylic acids which can be employed as useful intermediates for the production of various types of fluorine-containing compounds.

A still another object of the invention is to provide a profitable process for the manufacture of aliphatic w,wdi (triuoromethyl) perfluorocarboxylic acids having the aforesaid characteristics.

Other objects and specic features of the invention will become apparent in view of the following:

The aliphatic w,w di- (triuoromethyl) perfluorocarboxylic acids of this invention are of the formula:

wherein nis an integer from 2 to 21.

The compounds of the aforesaid formula are:

Compound B.P. in O. Compound B.P. in O.

CFa 157 CFS 189.

CF(CF2):CO0H CF(CF2)4COOH CFa CF;

CF3 175 CF3 CF(CF3)3COOH CF(CF:)5COOH 205.

CF; CFa

CF3 218 CFs 315.

CF(CF2)|COOH CF(CF2)14COOH CF: CFa

CF; 233 CF1 240/50 mm. Hg.

CF(CF2)7COOH CF(CF2)15COOH CF3 CFB CF3 245 CFa 228/30 nlm. Hg:

CF (CFz)sCOOH CF (CFa)1|COOH CF: CF;

CFB 259 CF; 258/50 mm. Hgs

CF; CF;

C Fg 270 CF: 264/50 mm. Hg.

CF(CF2)10COOH \CF(CF3)1aCOOH C s CF1 CFS 282 OF5 268/50 mm. Hg.

CF(CFa)x1COOH CF (CFz)19COOH CF3 CF.

CFa 295 CFS 274/ mm. Hg.

CF(CF2)12CO0H CF(CF2)20COOH CF; CF;

C F3 305 CFB 284/50 mm. Hg.

CF (CFa)xaCOOH CF(CF2)21COOH CF; CFa

The compounds of the aforesaid formula in which n is from 2 to 6 are liquids at normal room temperature, whereas the compounds of said formula in which n is from 7 to 21 are solids at normal room temperature. All of the compounds of said formula are acidic and excell in resistance to heat, chemicals and weather. Said compounds have a particularly pronounced low order of surface tension in that they exhibit no more than 18 dynes/ cm. lal: the vicinity of critical micelle concentration in aqueous media.

Like the conventional straightchain aliphatic peruorocarboxylic acids, the branched-chain aliphatic w,w di-(trilluoromethyl)-peruorocarboxylic acids of this invention have a general tendency to decrease the surface tension of liquid media in which they are employed with an increase in the chain length of such branchedchain acids. As compared with the conventional straightchain aliphatic peruorocarboxylic acids,y however, the branched-chain w,w di (triuoromethyl)-peruorocarboxylic acids of this invention having theV same chain length or the same number of carbon atoms, as the convetional compounds exhibit a markedly low order of surface tension. This outstanding feature of the invention is readily apparent from a review of the attached drawings. FIG. 1 is a graph on which the concentration in mole/liter of water of various compounds is plotted against the surface tension properties of the resulting solutions.

In FIG. 1, 1ines A, B, and C represent such plottings for the compound CF, y omormooon y C Fa I of this invention, and conventional compounds CF3 (CP2) BCOOH and CF3 (CF2)4COOH, respectively. FIG. 2 is a graph on which similar plottings are made for compounds D, E and F, which are the compound C Fa A oFoFmoooH 4 C F 3 of this invention, and conventional compounds pounds A and D. Further, compounds A and D of this invention always provide a lower order of surface tension, particularly a. markedly lower order of surface tension in a concentration below the critical micelle concentration, than the straight-chain compounds C and F, which respectively have the same number of carbon atoms as compounds A and D and a longer chain length than compounds A and D.

Such phenomena as specified above indicate the possibility that the branched-chain aliphatic w,wdi(triuoro methyl)-perliuorocarboxylic acids of this invention and the salts, esters, amides, nitriles and polymers derived therefrom, to excell much more in water and oil repellency and surface active properties than the corresponding straight-chain aliphatic perliuorocarboxylic acids and the derivatives thereof. In fact, the water and oil repel-I lency experiments performed by the present inventors showed a marked difference in such properties between the two series of the compounds in question. For instance, an isopropanol solution containing 0.1 percent by weight of the chromium complex of a compound of the formula CF (CFMCOOH CFB of this invention imparts to gauze an ability to block the penetration of machine oil and liquid paraffin for more than 24 hours, whereas CF3(CF2)4COOH having the same number of carbon atoms but a longer chain could not protect gauze for no more than l() minutes when employed under the same conditions as specified above, and CF3(CF2)3COOH having the same chain length could not even block the penetration of liquid paraffin when employed under the same conditions as specified before. Such excellent water and oil repellency can be secured by the aliphatic uw di (trifluoromethyl)per fluorocarboxylic acids of this invention when employed in the form of, not only chromium complexes, but as zirconium salts, aluminum salts, or polyesters obtained by esterifying polyvinyl alcohol, or rubber-like polymers prepared by polymerizing esters of any of the aliphatic perfluorocarboxylic acids of this invention and an unsaturated alcohol, such as allyl alcohol, or derived from unsaturated esters, such as of the formula wherein n is as defined before, q is an integer from 2 to 4, and R stands for a hydrogen or methyl group.

The aliphatic w,wdi(trifluoromethyl)-perfluorocarboxylic acids of this invention and the derivatives thereof, further, possess marked surface active properties, exhibiting a pronounced ability for emulsifying, in aqueous media, polyfluorovinyl compounds, polyiiuoroalkenes and the polymers thereof, so that the peruorocarboxylic acids of this invention are very useful as agents for the emulsion polymerization of unsaturated polyuoro compounds as disclosed herein. For instance, as described in Example l below,

CF(CF2)4COON2\ 'of this invention provided a reaction speed and polymer concentration far greater than the straight-chain CF3 2) COONa.

having the same number of carbon atoms but a longer chain, when employed as an emulsifying agent for polymerizing tetrafluoroethylene in aqueous media under irradiation with ionizing radiations. As an emulsifying agent for such reactions, the carboxylic acids and the water-soluble salts derived therefrom of the formula M being sodium, potassium or ammonium, and n' being an integer from 2 to 21, particularly from 3 to l0, are profitably employed. The compounds of said formula not -only have pronounced emulsifying ability but also excell in resistance to chemicals, heat and weather, so that the aqueous emulsions of the tiuorine-containing polymers emulsified with `said agent are useful compositions having a wide range of application. For instance, the anionic compounds of the formula n being as defined before and r being an integer from 1 to l2, and the cationic compounds of the formula /omcrnnooNmcHnqoomir ora c1- are all profitably employed as useful surface active agents.

The aliphatic w,w-di-(trifluoromethyl)-periiuorocarboxylic acids of this invention can also be employed in the form of the original carboxylic acid or an acid anhydride as a profitable accelerator for the esterification reaction or the polymerization reaction of silicones. For instance, the derivatives of the formula of this invention, n being as defined before, are particularly useful as a cockroach attractant.

Thus, the aliphatic w,wdi(trifiuoromethyD-peruorocarboxylic acids and the derivatives thereof of this invention are not only useful in themselves but as intermediates for preparing water and oil repellants, surface active agents, anti-fouling agents, dyestus, insect attractants, insecticides, heat-proof resins and rubbers, and similar articles.

The aliphatic w,w-di(triuoromethyl)perliuorocarboxylic acids of this invention, further, possess lower melting points and higher solvent-solubilities than the straight-chain aliphatic perfluorocarboxylic acids having the corresponding number of carbon atoms, so that the compounds of this invention can be more easily processed than the conventional carboxylic acids. For instance,

of this invention is in a liquid state at normal room temperature, since the melting point thereof is about -10 C., Whereas CF3(CF2)5COOH having the corresponding number of carbon atoms is in a solid state at normal room temperature, the melting point thereof being 55 C.

Not only the aliphatic w,wdi(trifiuoromethyl)peruorocarboxylic acids of this invention but the derivatives thereof possess a high order of solvent-solubility. For instance, a polyester having an ester value of percent and which is obtained by esterifying in dimethyl formamide a polyvinyl alcohol having a polymerization degree of 500 and a saponiiication value of about 100 percent with an acid chloride of of this invention, can be easily dissolved in acetone or triuorotrichloroethane, producing a homogeneous solution, whereas the polyester having an ester value of 90 percent and which is prepared under the same conditions as described before with CF3(CF2)6COOH, which has the corresponding number of carbon atoms, is insoluble in acetone and difficult to dissolve in tritluorotrichloroethane, requiring a long period of stirring before being completely dissolved therein. These phenomena also verify the fact that the aliphatic w,wdi(triiluoromethyl)per uorocarboxylic acids of this invention and the derivatives thereof can be easily employed and possess a wide range of application.

As stated before, the aliphatic w,wdi(triuoromethyl) peruorocarboxylic acids of this invention display a gradual decrease in surface tension properties with an increase in the chain length of the acid employed. This ability, however, almost attens out when the value of n reaches or more, and the synthesis of such compounds becomes increasingly diicult. The most desirable compounds of this invention, accordingly, are those compounds of the aforesaid formula having n in the range of from 3 to 10.

The aliphatic w,wdi(triuoromethyl)-peruorocarboxylic acids of this invention are obtained by oxidizing any of the compounds of the following formulas:

CFs

CFa

CF(CFaCF2)m(CH-=CX5)X CF (IV) wherein Y is -Br or -I; X1 and X2 are respectively --H, -F, -Cl, -Br, or -I, said X1 and X2 being mutually exclusive in terms of -F; each of X3 and X4 is -H, -F, -Cl, --Br, -I, -OH, -R, -OR, -OCR, -OOCR, -ROH, -COOR, or -COOH, R being alkyl having from 1 to 3 carbon atoms; X5 and X6 respectively stand for -H, -Cl, -Br, or -I, said X5 and X6 being mutually exclusive in terms of -Hg m is an integer from 1 to l0; and pis an integer from 2 to 3.

Representative compounds of lFormulas I to IV are as follows,

(III) being designated by Rf for brevitys sake.

(1) Compounds of Formula I:

(2) Compounds of Formula II: RfCH2CHClI RfCH2CH(CH3)IBr RfCHzCHgBr RfCHClCHClI lRICHZCHIOOCCHa RfCHgCHICOOCH;i RCHZCHZI RCHZCHICHZOH RfCHClCFClBr (3) Compounds of Formula III: RfCH=CH2 RfCH=CHCOOH RfCH=CHCl RCH=CHCOOCH3 RCH=CFC1 RCH=CHOOCCH3 (4) Compounds of Formula IV: Rf(CH=CH)3Cl Rf (CH=CC1) 2C1 As an agent for oxidizing the compounds of Formulas I to IV, there are employed potassium dichromate and similar dichromates, potassium permanganate and similar permanganates, fuming sulfuric acid, or oxygen, Suitableoxidizing conditions should be determined in view of the species of the starting material and of the oxidizing agent to be employed. In the following are described the most desirable conditions for said oxidization re'actions which are illustrative only and not limiting the scope and extent of the present invention.

(A) OXIDATION OF THE COMPOUNDS OF FORMULA I The most desirable oxidizing agent for the oxidation of the compounds of Formula I is oxygen or fuming sulfuric acid.

(a) Oxidation with oxygen- The starting material is oxidized with oxygen employed in the order of from 3 to 7 moles per mole of the starting material under the irradiation of light, particularly visible light, or ultraviolet rays. The initial reaction pressure ranges from normal atmospheric pressure to 20 kg./cm.2, and the reaction temperature employed is from normal room temperature to about 50 C. There may be added chlorine, iodine or steam as an accelerator in the order of from /lo of a mole to equimolar amounts. As a source of oxygen or oxygen-containing gases, such as air, are profitably employed.

(b) Oxidation with fuming sulfuric acid.-In this instance, there is employed a 10 to 70 percent fuming sulfuric acid in the order of from 2 to 6 times the original weight of the starting material in terms of S03. The reaction is carried out at a temperature ranging from about to about 170 C. under normal atmospheric pressure, or under increased pressure, where necessary.

(B) OXIDATION OF THE COMPOUNDS OF FORMULAS II TO IV 11n addition to the aforesaid processes described under (A(a)) and (A(b)), there are employed as an oxidizing agent in the instant oxidation reactions permanganates or dichromates in amounts ranging from 1.5 to 5 moles per mole of the starting material in conjunction with an acid, such as concentrated sulfuric acid or glacial acetic acid, or an aqueous solution of alkali salt, such as sodium hydroxide or potassium hydroxide in the order of from an equimolar amount to l0 moles per mole of said oxidizing agent. The reaction is performed at a temperature ranging from normal room temperature to about C. under a pressure of from normal atmospheric pressure to the vapor pressure of the compound to be oxidized at the reaction temperature.

(C) SYNTHESIS OF THE STARTING MATERIAL CNCFZCFQMY or; wherein Y and m are as defined before.

(l) Synthesis of the compounds of Formula I.-The compounds of Formula I are manufactured by the addition reaction of a compound of Formula V and a compound of the formula CF2=CX1X2, X1 and X2 being as defined before, in the following manner:

(2) Synthesis of the compounds of Formula II.-The compounds of Formula II are produced by the addition reaction of a compound of Formula V and a compound of the formula CHF-C'XBX, X3 and X4 being as defined before, in the following manner:

(3) Synthesis of the compounds of Formula IIL- The compounds of Formula III are synthesized by the addition reaction of a compound of Formula V and acetylene or by dehydrohalogenation (-HY, Y being as defined before) of a compound of Formula Il in the following manner:

CF(F20I).(CH=CX)XI CF: (X)

Of the above reactions, the addition reactions of Equations VI, VII and VIII are carried out radically by the action of light, heat or a free radical initiator. An increase in the amount of the unsaturated compound employed generally promotes telomerization or similar phenomena. In order to improve the yield of the addition product without producing any undesirable by-products, the amount of the unsaturated compound to be employed should be carefully determined in View of the properties of the compound of Formula V to be employed therewith. Said amount also varies with the degree of self-polymerization potential. For instance, a compound having a high order of self-polymerization potential, such as CHFCHI, CH2=1CHOOOCH3, CHZIICH CH2=CHCOOCH3 or CHECH, is preferably employed in the order of from 0.1 to 0.9 mole per mole of the compound of Formula V. In order to raise conversion levels, such unsaturated compounds are added not in a single charge but incrementally or continuously. An unsaturated compound having a low order of self-polymerization potential, such as CHClrCHCl, CF2=OC12 or CF2=CHF is employed in an equimolar amount or may be added in excess in relation to the compound of Formula V.

When light is employed at the initial stage of reaction, visible light or ultraviolet rays is preferably employed at a temperature ranging from normal room temperature to about c7 C. The reaction pressure varies with the vapor pressure of the stock material. For instance, CH2=CHC1, CHFCHZ, CH.= CH or CFZ=CFH is preferably allowed to react in a closed vessel under autogenous pressure. There may however be employed an increased pressure ranging from 1 to 50 kg./cm.2. A reactant having a higher order of boiling point is employed in an open vessel by cooling under a reflux condenser. When heat is employed to initiate the reaction, the reaction is preferably carried out in a closed vessel at a temperature ranging from to 250 C. or thereabout. When a free radical initiator is employed, the reaction is desirably carried out at a temperature ranging from normal room temperature to about 150 C. under a pressure from l to 50 kg./ :m.2 The free radical initiator employed in processes of this invention tertiarybutylhydroperoxide, ditertiarybutylperoxide, benzoylperoxide, diisopropylperoxydicarbonate and similar organic peroxides, or azobisisobutyrontrile and similar organic azo compounds.

The dehydrohalogenating reaction of Equations IX and X can be carried out in various Ways. Particularly, said reaction is desirably performed with an alkali metallic compound, such as potassium hydroxide, sodium hydroxide or sodium carbonate, or with an alkali metal, such as metallic sodium, in a saturated alcohol, such as methanol, ethanol or isopropyl alcohol, in an open or a closed vessel at a temperature ranging from normal room temperature to about 100 C. Said dehydrohalogenating reaction, however, requires no particular reaction conditions. Any conventional method Imay be profitably employed.

m and Y being as defined before, and which are employed as a starting material for the production of the compounds of Formulas I to IV are synthesized by the reaction of a periluoroisopropyl halide of the formula CFY Y being as defined before with tetrauoroethylene by various procedures. It is desirable, however, to carry out the reaction with the aid of irradiation by ionizing radiation, a method which was devised by the present inventors and disclosed in their Japanese patent application No.

(D) SYNTHESIS OF 1 1 6,569/ 1964. Alternatively, the reaction may be profitably carried out in the presence of a free radical initiator, a method which was also devised by the present inventors and disclosed in our Japanese patent application No.

The irradiation sources employed in thev former method include a-rays, -rays, y-rays, X-rays,'neutron rays, proton rays, deutron rays and similar ionizing radiations, o'f which fy-rays, particularly y-'rays emitting'froinz Co60 are most preferable. The dosage rate ranges from 1X 102 r./hr. to 1 106 r./hr., particularly from 1 103 r./hr. to 1 105 r./hr., preferably withinthe total dosage rangeof from 1 103 to l 106 r. The reaction temperature and reaction pressure cau be varied over a Wide range. Namely, the reaction temperature to be used ranges from about the temperature of the liquid nitrogen employed to 'about Y 150 C., particularly from 90 to 100 C. Either reduced or elevated pressure may be used, but the reaction satisfactorily proceeds under normal atmospheric pressure or a pressure amounting to about 50 kg./cm.2. The starting peruoroisopropyl halide is preferably employed in the order of from 1 to 10 moles for 10 to 1 moles of the tetrauoroethylene to be employed therewith.

The free radical initiator employed in the latter of the aforesaid methods includes benzoylperoxide, ditertiarybutylperoxide, tertiarybutylperbenzoate, tertiarybutylhydroperoxide and similar organic peroxides, and azobisisobutyronitrile and similar organic azo compounds. The amount of said initiator to be employed ranges from 0.05 to 10 percent by weight, particularly from 0.5 to 5 percent by weight, in relation to the stock material. The reaction conditions vary with the properties of the initiator to be employed, but the reaction is profitably carried out at a temperature ranging from 50 to 200 C. under a pressure of from 5 to 200 kg./cm.2. In this reaction, the starting perfiuorosopropyl halide is employed in amounts of the order of from 1 to 5 moles for 5 to 1 mole of tetrauoroethylene, preferably from 1 to 3 moles per mole of tetrafluoroethylene. Whether ionizing radiations or free radical intiators are employed, the reaction can be satisfactorily carried out batchwise or discontinuously or continuously.

Thus, the desired aliphatic ,w-di-(triuoromethyl)-peruorocarboxylic acids of this invention can be easily obtained as notedabove from intermediates prepared by the reaction of the readily available periluoroisopropyl halides with tetrauoroethylene, thus producing the compounds of Formula V, from which the compounds of Formulas I to IV can be prepared.

In the following are described the preferred methods employed in this invention for the production of the compounds of the formula m being as defined before:

(1) There were placed in a 50G-cc. Hastelloy-C agitator-type autoclave, Hastelloy being a trade name, Union Carbide Corp., U.S.A., 185 grams (0.625 mole) of peruoroisopropylodide of the formula CFa CFI

Ca 0.7 gram of tertarybutylhydroperoxide, and 3.3v grams of ditertiarybutylperoxide. After freezing the mixture with liquid air, the air present in the autoclave was evacuated under reduced pressure. There were then added 35 grams of tetrauoroethylene, and the mixture was agitated while passing steam therethrough. The reaction temperature rose to 100.5 C. and the maximum pressure reached 20.5 lig/cm.2 10 minutes after application of the steam heating, but the pressure started gradually falling thereafter. When the pressure fell to 6 kgJcm.2 5 hours afterapplication of the steam heating, agitation and steam heating were suspended'and the autoclave was cooled' with water. Then the pressure fell to almost 0 kg./cm'.2, producing 217 gr rrns vof reaction products. When the lreaction products wereI fractionally'distilled,there were'obtained:

Grams, B.P. in C./

moles mm. Hg

Unreacted /O FI 139. 6(0. 472) CF(CF2GF2)I 20.9(0.'0`528) se to 88.5/760.

CFa"

CF(CF2CF2)2I 25. 3(0.'o510) 74 to 76/92 to 94.'

CF C@ 0F(CF2CF2)3I 13.1(0.0264) 69 to 72/10 to 11,5.

CF. Ca

CFCFaCFmI 10. 5(10. 01,76) 91v to 9 1.5/4.5 to 5.o.

CFS

CFa

CF(OF2CF)5I v 4. 2 125 to 12s/4.5 to 5.0.

Others 3.4

Conversion f Percent Perfluoroisopropyliodide 24.5 Tetrai'luoroethylene 96.1

(2) In accordance with the procedure as described in the former instance, there were placed in a 1liter Hastelloy-C autoclave 296 grams (1.00 mole) ofl peruoroisopropyliodide, grams (1.00 mole) of tetrauoroethylene, and 1.9 grams (0.048 mole) of azobisisobutyronitrile, and the mixture was reacted at 100 to 110 C. for 10 hours. When the resulting reaction products were frac- (3) There were placed in a ISO-cc. pressure glass cylinder 242.4 grams (0.819 mole) of peruoroisopropyliodide and 16.4 grams (0.164 mole) of tetrauoroethylene, and the mixture was frozen with liquid nitrogen. After the cylinder was closed airtight,1the air present in the cylinder was evacuated. The cylinder was then separated from the liquid nitrogen and gradually warmed atl roo'rrl temperature with stirring to thoroughly mixthe stock materials. Whenthe temperatureof themixture had risen to about normal `'room temperature and the pressure to 1.6

lig/cm?, the pressure cylinder was placed 20 cm. apart from a 2,000-curie Coso source, and the mixture was subjected for 2 hours to the irradiation of 'y-rays emitting from said radiation source. The resultant products contained when fractionally distilled:

\CF(CF2CF3)I 4.4 grams 13.1. 30 C./92.5 mm. Hg. et.

\CF(CF3CFQ)3I 0.6 grams. B.P. 29 C./37.5 mm. Hg. C 143 Conversion Percent Perfluoroisopropyliodide 1.50 Tetrauoroethylene 8.24

For a fuller understanding of the principles of this invention, there are provided in the following the preferred examples which are illustrative only and not limiting in any sense of the scope and extent of the invention.

EXAMPLE 1 ln a 150-cc. Hastelloy-C autoclave there were placed 150 grams (0.303 mole) of In a 1D0-cc. four-neck ask, in the next step, there were placed with stirring 18 grams of potassium hydroxide and 20 grams of ethanol. After complete agitation, there were added portionwise 68 grams of the aforesaid crude CFS CFs while maintaining the reaction temperature at around 50 to 60 C; by cooling the rising temperature due to the exothermic reaction. After such addition was completed, the temperature was raised to 80 C. and the agitation was continued for an additional lhour.

The resulting reaction product was thenpoured into 200 cc. of water. After separation of the oil phase, the liquid phase was extracted with chloroform. The resultant extract and the oil phase were then dehydrated together with magnesium sulfate anhydride and fractionally distilled after removing the chloroform, producing 49.5 grams (0.125 mole) f CFa CF oF2oFmCH=oHz CF: Yield was 96.2 percent on a mole basis.

Synthesis of 48 grams (0.121 mole) of the product thus obtained were then stirred at to 135 C. for 8 hours with a mixture of 74 grams of potassium dichromate, 162 grams of concentrated sulfuric acid and 58 grams of distilled water, and steam-distilled. The extract was then neutralized with a 5 percent potassium hydroxide aqueous Solution, evaporated and dried. The solid residue thus separated was placed in excess concentrated sulfuric acid and distilled under reduced pressure, producing 48 grams of Analysis-Calci (percent): C, 23.2; P, 68.8; H, 0.24. Found (percent): C, 23.0; F, 69.1; H, 0.27.

Other properties: M.P. 10.5 to 11.0 C.; 111,25, 1.3134; d425, 1.76 g./cc.

The compound thus prepared was neutralized with sodium hydroxide and recrystallized with toluene-n butanol anhydride, producing dried which displayed a marked effect on the emulsification polymerization of tetrafluoroethylene in aqueous media.

Namely, there were placed in a Z-Iiter agitator-type autoclave 0.3 percent by weight of said and 6 percent by weight of n-cetane as a stabilizer in 800 cc. of deoxidized distilled water. After evacuating the air present in the autoclave, tetrauoroethylene gas was introduced to pressurize the autoclave to thelevel of about 6 14g/cm.2 and the mixture was completely agitated. The mixture was then subjected to irradiation of ry-rays emitting from a 2,000-curie Co60 source. As the polymerization reaction progressed polymerization, the reaction temperature gradually fell. To compensate for this drop in the temperature, additional tetrauoroethylene was supplied to keep the reaction pressure at the level of about 6 kg./cm.2. After sustaining an irradiation dosage of 8X104 r., the mixture was allowed to post-polymerize for as additional 30 minutes. The resultant dispersion had a polymer concentration of 28.7 percent by weight, and the maximum reaction velocity was 4.1 moles per liter per hour, whereas when CF3(CF2)6COONa was employed as an emulsifying agent as a control under the same condij tions there was produced a dispersion having a polymer concentration of 20 percent by weight with the maximum reaction velocity reaching no more than 3.0 moles per liter per hour.

EXAMPLE 2 CFa CF(CF2)2COOH CFa Synthesis of In a SOO-cc. autoclave there were placed grams (0.392 mole) of acted acetylene, and the reaction mixture was fractionally distilled, producing 92.5' grams (0.219 mole) of CFS CFCFZCF2CH=CHI CFB 67.7 grams of runreacted ons CFCF2CF2I CFa EXAMPLE 3 CFa CF(CF2)uCOOH CFa In a 150-cc. Hasteloy-C autoclave there were placed 150 grams (0.252 mole) of v12.5 grams (0.200 mole) of vinyl chloride, and 1.9 grams of azobisisobutyronitrile, and the mixture was frozen with liquid air. After evacuating the air in the autoclave, the mixture was agitated at 100 to 110 C. for 90 minutes while heating with superheated steam. The reaction pressure fell from an initial value of 7.8 kg./cm.2 to 2 kg./cm.2. When further cooled to about room temperature, the pressure in the autoclave fell to an order level lower than normal atmospheric pressure, and no unreacted vinyl chloride separated out. When the resultant liquid reaction mixture of 162.1 grams was fractionally distilled,

Synthesis of vthere were obtained 38.1 grams (0.064 mole) of unreacted 118.5 grams (0.180 mole) of CF CF2CF2 3CH2CHC1I C Fs and 5.4 grams of other substances. Yield was 95.8 percent by mole.

Conversion:

74.6 percent on a mole basis'.

Vinyl chloride: 100 percent on a mole basis.

In the next step, there were placed in a 300-cc. fourneck ask 118.2 grams of the resultant I v CFa oFwFzoFmCHzCHCII 1'44 'gansf' pota'ss'iindichimafe,and 11'3 grains of distilled Water. There were then added portionwise with stirring 3.12 grams of concentrated sulfuric acid for 2 hours. Such a very active exothermic reaction took place, that the exothermic heat was controlled at the initial stage.` After the completion of such addition, agitation was continued for an additional 3 hours at a reuxing tern- Peratilref VWhen ha raion was O Hltsld.Y the mixture was steam-distilled, neutralized with diluted sodium hydroxide, evaporated to remove the water, extracted with ethanol to remove the sodium iodide, and filtered. The ethanol being removed,the ltrates were distilled with concentrated sulfuric acid Vemployed in an arnountl of about 2.5 times the original weight of the ltrates, producing 81.1 grams of v CFa omo'rzormooon CFa of B.P. 74 to 76 C./1.5 to 2.5 mm. Hg.

Arralysis.-Calcd. (percent): C, 23,34; F, 70.23; H, 0.19. Found (percent): C, 23.51; F, 69.88; H, 0.21.

Infrared absorption showed u c=0 at 5.67. Yield was 88.2 percent on a mole basis.

EXAMPLE 4 Ca synchesisof o F (orme o 0H C Fs f In a .SOO-cc. stainless steel autoclave there were placed 248 grams (0.5 mole) of f CFS CF(CF2CF2)2I CFa and 3.4 grams of ditertiarylautylperoxide, and the mixture was frozen with brine cooled with Dry Ice. After evacuating the airin the autoclave with nitrogen gas and then with CFg'rCFCl gas, there were added 46.6 grams (0.400 mole) of CFFCFCl, and the mixture was agitated carefully at.120 to 130 C. A violent reaction took place during the initial 30 minutes after the application of agitation, but the reaction gradually slowed down. When the reaction pressure fell to a constant level of 2.2 kg/cm..2 3.5 hours after the application of agitation, the reaction mixture was cooled to normal room temperature with cold water. There were thus obtained 295 grams of a liquid product containing almost no unreacted CFZ=CFCL The product thus obtained was then placed in a two-neck ask and fractionally distilled while passing nitrogen gas through the capillary tubes', producing 126.8 grams (0.256 mole) of unreacted CFa omorzormr CF@ of B.P. 75 to 76 C./4.0 mrn.1Hg,'90.6 grams (0.148

17 and 26.9 grams of other substances, totaling 156.6 grains in all. Conversion of concentrated sulfuric acid, there were obtained 98.2 grams of CF, CF1

CF(CF'.CF2)2I CF(CF2CF2)4COOH CFE 5 cri was 48.8 percent on a mole basis, and yield of CFa of B.P. 70 to 75 C./1.0 to 1.5 mm. Hg.

Analyss.-Ca1cd. (percent): C, 23.45; F, 71.18; H, CFWFZCMCFFC 0.16. Found (percelen c, 23.89; F, 70.09; H, 0.14. OF5 Molecular weight.-Calcd.: 614.18. Found: 612.5. was 60j percent on a mole basis Yield: 82.5 percent on a mole basis. 90 grams (0.147 mole) of the resultant EXAMPLE 6 una CF@ CF(CF2CF2)2CF2CFC1I Synthesis of CF(CF2)2COOH CFa CFs were then oxidized with fumng sulfuric acid at 150 C. In a 500ML 4 neck ask in which the air was comfor 10 hours, and ih@ resultant 20 pletely replaced with nitrogen gas there were placed GFS 396 grams (1.00 mole) of \oF(cFiCFi 2oriooF CFS CF: CFCFzCFzI was hydrolyzed, producing CFB Op, 86 grams (1.00 mole) of purified vinyl acetate, and 1.2 grams of azobisisobutyronitrile and the system was /CNCFFZMCFZCOOH heated at 60 to 75 C. for 6 hours. There were then CF further added 39.6 grams of of B P. 75 to 76 C./3.5 to 4.0 mm. Hg. Infrared analysis 30 CF! indicated ilczat 5.66. CFC? CF I EXAMPLE 5 2 2 CF: CF 112 f if'b "1 drh an grains o azo isiso utyromtri e, an e mixture Synthesis 0f CF(CF2)5COOH 35 was heated at 75 to 85 C. for 3 hours. When unreacted F 210 ,gi-5ms (030251015) of C CFCFRCFBI CF:

onronnir CF CF; and vinyl acetate were separated, there were obtained 419 grams of crude C F H O I. were reacted Wlfh 14 grams (025,0 mole) 0f Analysis-calca. ipicnti: C, 22.4; F, 43.3; r, 26.4; and grams Of dltel'tlalyblltylpel'x H 0.21. Found (Percent): C, F 42.1. I 26.9. ide at 120 to 130 C. for 4 hours. After separating 2.0 5 Hy 026l grams @036 mole) 0f Dreamed CHZZCHCH2CH3 and 400 grams of the crude product thus obtained were 66.8 grams (0.096 mole) 0f unfeacted reacted with 93 grams of potassium hydroxide in 100 cc. CFG of ethanol, and the mixture was poured into 600 cc. of Water, extracted with chloroform, dried with magnesium CMCFFI sulfate anhydride, and heated to expel the chloroform. CF;i The brownish liquid residue of 297 grams thus obtained a was placed in a 2-liter 4-neck flask and oxidized with there were obtained 0.194 mole of a 1:1 molar addition stirring with 700 grams of potassium dichromate and product and 9.2 grams of other substances. Conversion of 1,700 grams of Concentrated sulfuric acid in 567 grams CF of distilled Water at 120 to 135 C. for 8 hours. The 3 resultant mixture was then steam-distilled, neutralized om /CFtC F20 F041 with 5 percent potassium hydroxide, and heated to dispel and CHFCl-ICI-IZCHa were respectively 68.2 percent on a mole basis and 85.6 percent on a mole basis. Yield of the 1:1 molar addition product was 94.2 percent on a mole basis.

With the resultant 1:1 molar addition product there were then reacted with stirring 260 grams of sodium permanganate and 1,500 grams of glacial acetic acid at 100 C. for l0 hours. After decoloring the resulting product with sulfurous acid gas, the acetic acid was removed by distillation, and the separated solids were placed in 10 percent H2804 and continuously extracted with ether. To the resultant ether solution there was added methanol in a quantity of about 2 times the original volume of ether, and the mixture was carefully neutralized with a 20 percent sodium hydroxide aqueous solution, evaporated, and dried, producing 108 grams of light brownish solids. When fractionally distilled with the water, producing 273 grams of light yellowish powder. When fractionally distilled with concentrated sulfuric acid under reduced pressure, there were obtained 99.0 grams of CFCFaCFzCOOH EXAMPLE 7 CFS Synthesis o! In a 150-cc. pressure glass cylinder were placed 89.8

grams (0.20 mole) of CFS v of B.P. 51 to 52 C./60 mm. Hg and 9.7 grams (0.10 mole) of cis-1,2-dichloroethylene, and the mixture was frozen with liquid air. After closing the cylinder airtight, the air present was evacuated, and the temperature was gradually raised with stirring to allow the two ingradients to mix thoroughly. When the temperature was raised to about room temperature, the cylinder was placed cm. apart from a 2,000-curie C06o source and subjected for 3.5 hours to irradiation of y-rays emitting from said source. Fractional distillation of the irradiated sample produced a 1:1 molar addition product (yield: 21.5 percent on a mole basis) and 1:2 molar addition product (yield: 10.3 percent on a mole basis).

Analyss.-Calcd. for C9F15Cl2BrH2 (percent): 19.8; F, 52.2; Cl, 13.0; Br, 14.6. Found (percent): 20.2; F, 51.3; Cl, 13.1; Br, 14.1.

Analyss.-Calcd. for C11F15Cl4BrH4 (percent): 20.5; F, 44.3; Cl, 22.1; Br, 12.4. Found (percent): 20.4; F, 43.1; Cl, 23.8; Br, 11.7.

When grams of said CFa CF(CF2CF2)2CHC1CHC1Br were oxidized with potassium chromate, concentrated sulfuric acid and distilled water as described in Example 1, there was obtained the desired CF(CF2OF2)2CO0H CFa in a yield of 84.7 percent on a mole basis.

EXAMPLE 8 CFa In a SOO-cc. stainless steel autoclave were placed 198 grams (0.500 mole) of Synthesis of 3.4 grams of ditertiarybutylperoxide, and the mixture was frozen with brine cooled with Dry Ice. After replacing the air in the autoclave with nitrogen gas, there were added 46.6 grams (0.400 mole) of CFZCFCl. The mixture was then carefully warmed and stirred at 120 to 130 C. A violent reaction took place for the initial 30 minutes after the application of stirring. But the reaction gradually slowed down thereafter, and the pressure fell to the constant level of 2.2 kg./cm.2 3.5 hours after the application of stirring. When the resultant mixture was allowed to cool to normal room temperature, there were obtained 245 grarns of a liquid reaction mixture containing almost no unreacted CF2CFC1. Fractional distillation of the mixture produced 81.2 grams (0.205 mole) of CFS CF(CF2CF2)I CFs 130 grams (0.254 mole) of CFa CF CF2CFZCFQCFC11 CMCFQSCOF CFa of B.P. 68 to 70 C. in a yield of 71.3 percent on a mole basis and having an intense vc=0 infrared absorption at 5.27, 10.5 grams (0.0205 mole) of unreacted and 2.1 grams of other substances. Conventional hydrolysis of 10 grams of said reaction product produced CFa CF(CF2)3COOH CFs of B.P. 67 to 70 C./10 mm. Hg in a yield of 93.8 percent on a mole basis.

While the invention has been described with particular reference to specific embodiments, it is to be understood that it is not to be limited thereto but is to be construed rather broadly within the scope and extent of the appended claims.

We claim:

1. A method of preparing an w,wdi(triiluoromethyl) pertluorocarboxylic acid of the formula:

oFwFmCooH CF3 wherein n is an even integer from 2 to 20, which comprises oxidizing with at least one member of the group consisting of alkali metal chromate, alkali metal permanganate, fuming sulfuric acid and oxygen, a compound selected from the group consisting of the compounds o f the formula:

wherein Y is a member selected from the group consisting of Br and -I; X3 and X4 are each a member selected from the group consisting of -H, P, -Cl, -Br, -I, OH, -R, OR, -OCR, -OOCR, -ROH, -COOR and -COOH, R being alkyl having from 1 to 3 carbon atoms; and m is an integer from 1 to 10.

2. A method of preparing an w,wdi(triuoromethyl) peruorocarboxylic acid of the formula:

c Fa

or (orancoon wherein n is an even integer from 2 to 20, which com! prises oxidizing with filming sulfuric acid at a temperaf.

ture of from 90 to 170 C., a compound selected from the group consisting of the compounds of the formulas:

wherein Y is a member selected from the group consisting of -Br and -I; X3 and X1 are each a member selected from the group consisting of H, -F, -Cl, Br, -I, -Ol-I, --R, -OR, OCR, --OOCR, -ROH, -COOR and -COOH, R being alkyl having from 1 to 3 carbon atoms; each of X5 and X6 stands for a member selected from the group consisting of -H, -Cl, Br, and -L said X5 and XG being mutually exclusive in terms of -H; m is an integer from 1 to 10; and p is an integer from 2 to 3.

3. A method according to claim 2 wherein said compound has the formula:

4. A method according to claim 2 wherein said compound has the formula:

CF(CF2CF2).(CH=CX)DX6 References Cited UNITED STATES PATENTS LORRAINE A. WEINBERGER, Primary Examiner 0 P. I. KILLOS, Assistant Examiner U.S. Cl. X.R.