DE1049862B - Process for the perfluoroalkylation of aromatic compounds - Google Patents

Description

GERMAN

The invention relates to a new and useful process for the perfluoroalkylation of aromatic compounds, one or more perfluoroalkyl chains being bonded to an aromatic nucleus. The perfluoroalkylation \ 'on dyes is of particular interest.

According to the present invention, the perfluoroalkylation is effectively carried out by making a mixture from the aromatic starting compound and a perfluoroalkyl monoiodide which has 3 to 12 carbon atoms in the molecule has, heated to a temperature of about 200 to 350 ° C, creating one or more nuclear hydrogen atoms of the aromatic molecule can be replaced by perfluoroalkyl chains that are 3 to 12 completely have fluorinated carbon atoms.

It has been found that the process is based on a large number of very different aromatic compounds that are present in are resistant to the temperatures used and contain hydrogen atoms that are attached to an aromatic Core bound is generally applicable. It has been found that the method works on aromatic compounds is applicable that have ring substituents, these substituents remaining unaffected and the Implementation remains limited to the hydrogen atoms. The process is also applicable to polynuclear aromatic compounds, such as naphthalene, and multicore dyes can be used.

A feature of this process is that economically viable yields (e.g. 30%) of the perfluoroalkylated products can be obtained. The process gives a compound in useful yield, which corresponds in its structure to the starting compound.

An important feature of the process is that, in contrast to processes, their practical Usability is limited to reactants and products containing a single fluorinated carbon atom contain (e.g. trifluoromethyl compounds) - is suitable for making compounds that have fluorocarbon chains having 3 or more carbon atoms. As the chain length increases, it occurs no drop in yield. Perfluoroalkyl chains containing 3 to 12 carbon atoms are particularly Interest because it has been found that their introduction into an aromatic compound increases the solubility and surface-active properties Properties in a useful way change strongly, which is due to the hydrophobic and oleophobic Properties of the fluorocarbon chains that are introduced into the aromatic nucleus in the process is.

The perfluoroalkylated products of the process are stable and generally have a greater thermal and chemical resistance than the starting compounds. Solubility in oils, hydrocarbon processes for perfluoroalkylation
aromatic compounds

Applicant:

Minnesota Mining and Manufacturing
Company, St. Paul, Minn. (V. St. A.)

Representative: Dr.-Ing. H. Ruschke, Berlin-Friedenau,

and Dipl.-Ing. K. Grentzenberg, Munich 27,

Pienzenauerstr. 2, patent attorneys

Claimed priority:
V. St. v. America August 12, 1955

George VD Tiers, St. Paul, Minn. (V. St. Α.),
has been named as the inventor

Substances and the usual organic solvents is reduced. The Perfluoralkylierungsprodukte are particularly sparingly soluble or insoluble when is achieved by introducing one or more perfluoroalkyl groups having 3 to 12 carbon atoms in the molecule a fluorine content of about 50 ⁰ Z ₀ or more. The solubility in fluorine-containing solvents is retained or increased. Products can be obtained which are very sparingly soluble in water, hydrocarbons and common organic solvents, but which have considerable solubility in fluorocarbon and chlorofluorocarbon solvents.

Many novel compounds can be made by the present process.

Of particular interest are - because of the novel properties and because of the versatility of the Process illuminate - the perfluoroalkylated phthalic anhydride, from which novel and valuable alkyd type resins can be made, and perfluoroalkylated Dyes. Dyes and color pigments can be produced using polytetrafluoroethylene are compatible and used successfully for dyeing and printing these fluorocarbon polymers that are not stained by ordinary dyes. Phthalocyanine dyes and pigments, ζ. B. copper phthalocyanine can be perfluoroalkylated.

The method of the present invention consists in heating a mixture of the aromatic ingredients

509 748.452

transition compound and a perfluoroalkyl monoiodide containing 3 to 12 carbon atoms in the molecule, to one Temperature of about 200 to 350 ° C and the separation of the pcrfluoralkylicrtcn product from the reaction mixture - optionally using fluorine-containing, organic solvents - in a manner known per se. Implementation is because of the evolving Pressure carried out in an autoclave or in a pressure tube.

The following equation shows the implementation in its simplest form, replacing a nuclear hydrogen atom will:

HAr + 2 RJ> R, Ar + R, H -f J ₂

In this equation, Ar is the remainder of the aromatic molecule to which the hydrogen atom is attached, which is then replaced by the perfluoroalkyl group R ₇ . This replaceable hydrogen atom is bonded directly to a carbon atom of the aromatic ring, as is the perfluoroalkyl substituent after the reaction has ended.

The simplest form of the process is provided by the reaction of benzene with perfluoropropyl iodide, where perfluoropropylbenzo] (phenylperfluoropropane) is obtained:

HC ₆ H ₅ + 2C ₃ F ₇ J

> C ₃ F ₇ • C ₆ H ₅ + C ₃ F ₇ H + J ₂

The perfluoroalkylated product has the structural formula 1-CF ₉ -CF ₂ -CF ₃

This type of molecule is hydrophobic at both ends, oleophilic at the benzene end, and fluorocarbon end oleophobic. It can be because one end of the molecule is in the oil phase and the other end in the fluorocarbon phase is soluble, as a surfactant, e.g. B. used in the production of oil-fluorocarbon emulsions will.

Polysubstituted aromatic products are usually obtained in low yields as by-products, even if equimolar ratios of the starting compounds are used. Greater yields can by increasing the molar ratio of perfluoroalkyl iodide to aromatic compound or by Use of an already perfluoroalkylated aromatic compound can be obtained as the starting compound, which has previously been produced by the process.

The following exemplary embodiments describe the method according to the invention and also explain the Properties of the discussed compounds.

example 1

The reaction vessel was a 180 ecm shaking autoclave made of stainless steel, which was closed by a nickel ^{disk that could be loaded with 210 kg per cm 2.} It was charged with 90.0 g of n-perfluoropropyl iodide and 23.4 g of benzene so that a molar ratio of 1: 1 was obtained. The autoclave was heated to an internal temperature of 250 ° C. and shaken for 15 hours; it was then blown off, the liquid reaction product poured out and filtered to remove iodine crystals, 39.5 g of crude product being obtained. This was treated with mercury to remove traces of free iodine and then fractionated through a fractionating column with a 10 cm high filling with glass bodies.

This gave 22.3 g of relatively pure perfluoropropylbenzene which had a boiling point of 132 ° C. at 760 mm and a refractive index of 1.3790 at 25 ° C. The analysis showed 54.1% C (calculated 54.0%) and 43.9% F (calculated 43.9%). The yield was 30% based on C ₃ F ₇ J.

The higher-boiling fractions (total amount 4.7 g) were passed through a column with an outer diameter of 8 mm, which was filled with 1.5 cm of finely divided silica gel, and fractionated in the order of their lowering boiling points. The first fractions weighing 1.5 g (3% yield) consisted of di (perfluoropropyl) benzene as determined by analysis which were 34.8% C (calculated 34.8%) and 62.5 % F (calculated 64.3%) yielded. The refractive index at 25 ^C C was 1.3492. The composition of the infrared spectrum indicated that a mixture of isomers had formed.

Example 2

Using the same procedure, an equimolar mixture of 110.0 g of n-perfluoroheptyl iodide and 17.3 g of benzene was reacted at 250 ° C for 15 hours. Perfluoroheptylbenzene, C ₇ F ₁₅ C ₆ H ₅ , was obtained in a yield of 32% of the total conversion. The boiling point was 200 ° C. at 760 mm and the refractive index 1.3596 at 25 ° C. The analysis gave 35.0% C (calculated 35.0%) and 64.0% F (calculated 63.9%).

In addition, di- (perfluoroheptyl) -benzene was obtained in 4% yield obtained, which has a boiling point of 270 ° C at 760 mm and a melting point of 88 ° C would have. The analysis showed 29.5% C (calculated 29.5%) and 69.9% F (calculated 70.1%).

Example 3

The 14-hour reaction of 10 Ogn perfluoroheptyl iodide and 0.9 g of toluene in a thick-walled, fire-resistant 30 cm glass tube at 290 ° C. gave a mixture which was extracted with the solvent described below, whereupon the solution was fractionally distilled to give a product which was identified as perfluoroheptyltoluene and was obtained in a yield of 31%. It had a boiling point of 217 ⁰ C (at 760 mm) and a refractive index of 1.3678 at 25 ° C. The analysis showed 37.0% C (calculated 36.6%) and 60.4% F (calculated 61 9%). The infrared spectrum indicated nuclear substitution.

The solvent used was a cyclic fluorinated ether, which is essentially a mixture of perfluoro (2-methyltetrahydropyran) and perfluoro (2-ethyltetrahydrofuran) and which, for the sake of simplicity, is hereinafter referred to as "cC ₆ F ₁₂ O solvent" .

Example 4

The 13-hour reaction of 7.4 g of n-perfluoroheptyl iodide and 3.8 g of naphthalene in a thick-walled, fire-resistant 30 cm glass tube at 300 ° C gave a mixture from which the desired product was obtained by a Soxhlet extraction with the CC ₆ F ₁₂ O-solvent and subsequent vacuum distillation was obtained.

The perfiuorheptylnaphthalene was obtained in a yield of 31%. The refractive index was 1.4160 at 25 ° C. The analysis showed 42.5% C (calculated 41.2%) and 58.0% F (calculated 57.5%).

Example 5

The 20-hour reaction of a mixture of 10.0 g of n-perfluoroheptyl iodide and 2.1 g of benzonitrile (phenyl cyanide), C ₆ H ₅ CN at 300 ° C in a tube made of refractory glass gave a mixture from which the desired product with the CC ₆ F ₁₂ O solvent was extracted. The residue of the extract was purified by vacuum sublimation.

The perfluoroheptylbenzonitrile, C ₇ F ₁₅ C ₆ H ₄ CN, was obtained in 26% yield. It had a boiling point of 254 ° C. at 760 mm and a melting range of 45 to 52 ° C. The analysis showed 2.94% N (calculated 2.97%) and 35.7% C (calculated 35.7%).

Example 6

The 13-hour reaction of a mixture of 10.0 g of n-perfluoroheptyl iodide and 3.2 g of bromobenzene at 300 ° C. in a tube made of refractory glass gave a mixture which was extracted with cC _e F ₁₂ O solvent and fractionally distilled.

Perfluoroheptylbromobenzene, C ₇ F ₁₅ C ₆ H ₄ Br, was obtained in 30% yield and had a boiling point of 237 ° C at 760 mm and a refractive index of 1.3870 at 25 ° C. Analysis showed 29.2% C (calculated 29.8%) and 14.9% Br (calculated 15.2%).

Example 7

In the same way, iodobenzene was reacted with n-perfluoroheptyl iodide, with perfluoroheptyl iodobenzene, C ₇ F ₁₅ C ₈ H ₄ I, being obtained in 38% yield, which had a boiling point of 253 ° C at 760 mm and a refractive index of 1.4152 25 ° C. The analysis showed 27.1 ⁰ Z ₀ C (calculated 27.5%), 22.8% J (calculated 22.5%) and 49.4% F (calculated 50.1%).

Example 8

The 14-hour reaction of a mixture of 10.0 g of n-perfluoroheptyl iodide and 1.5 g of phthalic anhydride (molar ratio 2: 1) in a refractory glass tube at 320 ° C gave a mixture that by extraction with hot CC ₆ F ₁₂ O solvent such as was worked up above. The extraction was carried out in a Soxhlet apparatus. A brown oily solid substance deposited upon cooling. It was placed in a refractory glass tube with a diameter of 16 mm and a length of 35 cm, which was closed at one end; the other end was connected to a vacuum oil pump. Sublimation occurred at 150 ° C and 0.01 mm pressure and gave 3.7 g of colorless but somewhat moist crystals, which probably consisted of a mixture of isomers, since only one sublimate fraction was noticed. This product was _{recrystallized twice from CC 8} F ₁₆ O solvent and sublimed again in order to convert any acid formed back into the anhydride. The c-CgF ^ .- O solvent is a cyclic fluorinated ether, which is in principle a mixture of perfluoro (2-n-butyltetrahydrofuran) and perfluoro (2-n-propyltetrahydropyran).

The product was obtained in a yield of 36% and identified as a pure mixture of perfluoroheptylphthalic anhydride isomers (C ₇ F ₁₅ ) C ₆ H ₃ (CO) ₂ O. It melted at 121 to 124 ° C. The infrared spectrum showed the two bands characteristic of the anhydride of a carboxylic acid. The analysis showed 35.0% C (calculated 34.9%) and 55.1% F (calculated 55.2%). The saponification number was 258 to 268 (calculated value 258).

Perfluoroalkylated dyes

The perfluoroalkylation process can be applied to more complex aromatic starting compounds that are so heat-resistant that they do not change when heated to the reaction temperature to be used (in the range of about 200 to 350 ° C) decompose, and contain hydrogen atoms that are attached to aromatic Carbon atoms are bonded.

Of particular interest is the use of the process for the preparation of perfluoroalkylated dye compounds, which are stable at temperatures of at least 200 ° C, which is at least about 50 percent by weight Contain fluorine and those found in hydrocarbon solvents and other common organic solvents Solvent insoluble, but soluble in fluorinated solvents. These dyes are insoluble in water and both hydrophobic and oleophobic. They are compatible with polytetrafluoroethylene and can be used for Dyeing and printing of this polymer can be used.

ίο The process can be used for the perfluoroalkylation of Intermediate products are used, which are then converted into the dyes. The direct perfluoroalkylation of completely formed dyes is illustrated by the following examples.

Example 9

Perfluoroalkylated copper phthalocyanine

The parent compound has often been referred to as a dye, but is more precisely viewed as a pigment, because it is essentially insoluble in all solvents. It is very stable and sublimates in a high vacuum without decomposition at 550 ° C.

The introduction of four n-perfluoroheptyl residues into the molecule results in a permanent dye that is soluble in fluorine-containing solvents but insoluble in fluorine-free solvents. Strong blue solutions can be found at room temperature in the CC ₈ F ₁₆ O and CC ₈ F ₁ , 0 solvents described above and in perfluoro (di-n-hexyl ether), perfluoro (tri-n-butylamine), benzotrifluoride and 1 , 2-difluorotetrachloroethane, but no color is found in fluorine-free liquids such as benzene, n-heptane, acetone, ethyl alcohol, water, carbon tetrachloride or trichlorethylene.

A thick-walled, refractory glass tube with a capacity of 30 ecm was charged with 1.4 g of copper phthalocyanine and 10.0 g of n-perfluoroheptyl iodide in a molar ratio of 1: 8 and sealed in vacuo. The tube was heated to 330 ° C for 14 hours. The reaction product was subjected to extraction in a Soxhlet apparatus with cC ₈ F ₁₃ O solvent as above, whereby an intense blue solution was obtained, from which the solvent was evaporated, leaving 2.7 g of a dark blue-black powder. The residue was subjected to a further Soxhlet extraction with benzotrifluoride (CF ₃ C ₆ H ₅ ), whereupon the nitrated solution was evaporated to dryness, so that a further 1.7 g of the product were obtained.

Analysis showed that both products consisted primarily of tetra (perfluoroheptyl) copper phthalocyanine, which has the following empirical formula: C ₆₀ F ₆₀ H ₁₂ M ₈ Cu. This compound contains 55.7% F. From the nitrogen percentage it was found that the two fractions were present in a purity of 75 and 85 ⁰ Z _0, respectively.

Spectroscopic examination of the product in the visible area in CC ₈ F ₁₆ O solvent showed an absorption maximum at 6160 A. Based on the molecular weight of the pure compound, the molar extinction coefficient is about 30,000. The contamination was easily removed by vacuum sublimation. The perfluoroalkylated dye melts at around 300 ° C, although it is not volatile even in a vacuum at temperatures up to 350 ° C.

The purified product has mainly visible absorption wavelengths at 6550 to 6590 A and at 6200 A when it is dissolved at 0.070 g per liter of cC ₈ F ₁₆ O solvent. The corresponding absorption wavelengths of the original copper phthalocyanine are

at 6700 and 6400 A (saturated solution in xylene). the

Perfluoroalkylation thus results in a; ■ blue shift « the absorption, d. H. a certain shift in the Absorption at higher frequencies or shorter wavelengths.

Concentrated sulfuric acid dissolves the copper phtbalocj'anin to a blue solution, from which it can be recovered unchanged by adding water can. The tetra (perfluorhepty]) copper phthalocyanine reacts with sulfuric acid, but the reaction product is neither in sulfuric acid nor in fluorocarbon compounds soluble and forms a third when the solution is mixed with fluorocarbon solvent Phase; when adding water to the sulfuric acid solution however, the blue dye regresses.

Example 10

The perfluorination of vat dyes results valuable dyes which contain at least 50% fluorine and which are soluble in organic solvents containing fluorine, but are insoluble in hydrocarbons and in water.

Thioindigo and n-perfluoroheptyl iodide were heated in a molar ratio of 1: 4 in a tube made of refractory glass 2V at 330 ° C for _{2 hours.} The product was extracted with cC ₆ F ₁₂ O solvent in a Soxhlet extractor, whereupon the solution was freed from the solvent by distilling off. The residue was purified by sublimation at 250 ° C and 0.01 mm Hg. The purified product was _{soluble in cC 8} F ₁₆ O solvent with a red color. The main absorption wavelength in the visible area was 5140 Å, in contrast to 5440 Å for the thioindigo.

Using the same procedure, pyranthrones were reacted with n-perfluoroheptyl iodide in a molar ratio of 1 to 5.4 by heating at 340 ° C. for one hour, and the purified product was obtained. The dye produced was yellow and _{soluble in cC 6} F ₁₆ O solvent. The main absorption wavelength in the visible region was 4120 Å, in contrast to the main absorption wavelengths of 4720, 4400 and 4140 Å of the parent compound.

The reaction of violanthrone with n-perfluoroheptyl iodide in a molar ratio of 1: 5.9 gave a red dye which was _{soluble in cC 8} F ₁₆ O solvent. The main absorption wavelength in the visible area was 5050 Å, in contrast to 5870 Å for the parent compound.

The reaction of λόπ dichloroisoviolanthrone with n-perfluoroheptj'l iodide in a molar ratio of 1: 6.8 gave a λ-iolette dye which was _{soluble in cC 8} F _lc O solvent. The main absorption wavelength in the visible region was 5350 Å, in contrast to 5780 Å for the parent compound.

The foregoing examples of perfluoralk3 ^T profiled dyes have been successfully for dyeing λ ⁷ οπ PoIytetrafluoräth3 used len *, where clear or translucent colors were obtained of excellent heat resistance.

The dyes have also been used successfully for printing polytetrafluoroethylene films.

Claims (3)

Patent claims 1. A process for the perfusion of aromatic compounds which contain hydrogen atoms bonded to an aromatic nucleus and which are stable at the reaction temperature, characterized in that the aromatic compound is mixed with a perfluoroalkylene monoiodide which contains 3 to 12 carbon atoms in the molecule at a temperature of about 200 to 35O ⁰ C and the perfluoroalk3 ^r lated compound is separated from the reaction mixture in a known manner, optionally using fluorine-containing organic solvents, and recovered. 2. The method according to claim 1, characterized in that the aromatic compound phthalic anhydride or a polynuclear aromatic compound is used. 3. The method according to claim 1 and 2, characterized in that an aromatic dye, such as copper phthaloc3 "anin, or a vat dye used as a starting compound. © 809 748/452 1.59