Method for Preparing Halogen-Functionalized Polysiloxanes

Abstract

The present invention relates to a procedure in which a functionalized polysiloxane is synthesized in the presence of a platinum catalyst, and halogen-functionalized polysiloxanes obtained according to the procedure. The procedure is defined herein by reacting a) at least one polysiloxane comprising at least one hydrogen atom bonded to a silicon atom; b) at least one heterocyclic compound; and c) at least one halogen-containing compound, wherein the reaction is catalyzed by at least one platinum catalyst. The synthetic pathway is described as a halosilation reaction in which a heterocyclic molecule is ring-opened in the presence of a platinum catalyst and a halogen source, resulting in a formal insertion of the opened heterocycle into the SiH bond. On the final product, the heteroatom of the former heterocycle is bonded to the silicon atom from the former hydrosiloxane moiety while the halogen is bonded to the last carbon atom of the opened chain.

Claims

1. A method for preparing a halogen-functionalized polysiloxane by reacting a) at least one polysiloxane comprising at least one hydrogen atom bonded to a silicon atom; b) at least one heterocyclic compound; and c) at least one halogen-containing compound; wherein the reaction is catalyzed by at least one platinum catalyst.

2. The method according to claim 1, wherein the platinum catalyst is selected from the group consisting of chloroplatinic acids; alcohol modified chloroplatinic acids; olefin complexes of chloroplatinic acid; complexes of chloroplatinic acid and divinyltetramethyldisiloxane; fine platinum particles adsorbed on carbon carriers; platinum supported on metal oxide carriers; platinum black; platinum acetylacetonate; platinous halides; complexes of platinous halides with unsaturated compounds; styrene hexamethyldiplatinum; platinum divinyltetramethyldisiloxane complex; the reaction product of chloroplatinic acid and an unsaturated aliphatic group-containing organosilicon compound; and a neutralized complex of platinous chloride and divinyltetramethyldisiloxane.

3. The method according to claim 1, wherein the platinum catalyst is hexachloroplatinic acid or platinum divinyltetramethyldisiloxane complex.

4. The method according to claim 1, wherein the platinum catalyst is present in an amount of from 0.0001 mol % to 10 mol % of platinum based on the molar quantity of silicon-bonded hydrogen in the polysiloxane.

5. The method according to claim 1, wherein the polysiloxane comprising at least one hydrogen atom bonded to a silicon atom is a linear- or cyclopolysiloxane, or a mixture thereof.

6. The method according to claim 1, wherein the obtained halogen-functionalized polysiloxane has a number average molecular weight of from 100 to 50,000 g/mol.

7. The method according to claim 1, wherein said halogen-functionalized polysiloxane has the general Formula (I) or (I-A) or is a mixture thereof: ##STR00009## wherein: R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 may be the same or different and each is independently selected from a hydrogen atom or a linear, branched or cyclic hydrocarbon residue having 1 to 20 carbon atoms which may contain at least one heteroatom; A is a heteroatom, or a heteroatom-containing group, or NR.sup.7 or PR.sup.7, where R.sup.7 is selected from a hydrogen atom, a C.sub.1-C.sub.8 alkyl group, a C.sub.3-C.sub.10 cycloalkyl group, a C.sub.6-C.sub.18 aryl group or a C.sub.6-C.sub.18 aralkyl group, which may contain at least one heteroatom; Z is selected from a linear, branched or cyclic hydrocarbon residue having 2 to 60 carbon atoms which may contain at least one heteroatom; X is a halogen atom; in Formula (I) n1 is an integer from 1 to 1000, n2 is an integer from 0 to 100, and p is an integer from 0 to 1000; in Formula (I-A) n1 is an integer from 1 to 100, n2 is an integer from 0 to 10, and p is an integer from 0 to 100, wherein the sum p+n1+n2 is equal to or higher than 3.

8. The method according to claim 1, wherein said polysiloxane comprising at least one hydrogen atom bonded to a silicon atom has the general Formula (II) or (II-A) or is a mixture thereof and said halogen-containing compound has the general formula (III): ##STR00010## wherein: R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 may be the same or different and each is independently selected from a hydrogen atom or a linear, branched or cyclic hydrocarbon residue having 1 to 20 carbon atoms which may contain at least one heteroatom; in Formula (II) n is an integer from 1 to 1000 and p is an integer from 0 to 1000; and in Formula (II-A) n is an integer from 1 to 100 and p is an integer from 0 to 100, wherein the sum p+n is equal to or higher than 3, ##STR00011## wherein: X is a halogen atom; and R.sup.a is selected from the group consisting of a hydrogen atom or a linear, branched or cyclic hydrocarbon residue having 1 to 20 carbon atoms which may contain at least one heteroatom.

9. The method according to claim 1, wherein the reaction is carried out in at least one solvent.

10. The method according to claim 1, wherein the reaction is carried out at the temperature of from 0 to 200° C. and/or a reaction pressure of from 1 to 50 bar.

11. A halogen-functionalized polysiloxane obtained by the method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0076] FIG. 1 shows the conversion of SiH moieties compared to the time of Examples 1 to 3.

[0077] FIG. 2 shows the logarithmic plotted conversion of SiH moieties compared to the time of Comparative Examples 6 to 8.

[0078] Various features and embodiments of the disclosure are described in the following examples, which are intended to be representative and not limiting. The following examples serve to explain the invention, but the invention is not limited thereto.

EXAMPLES

Example 1: Preparation of 3-(4-bromobutoxy)methylsiloxane

[0079] ##STR00004##

[0080] A 250 ml three neck round bottomed flask was degassed under high vacuum (1.sup.−3 mbar) and flushed with argon. Then, 200 μL of Karstedt (2% of Pt in the catalyst, 0.1% mol in the mixture) and toluene (50 mL, dried over molecular sieves) were added into the flask under argon atmosphere and stirred at room temperature (20° C.) for a couple of minutes. Then tetrahydrofuran (18.5 mL, dried over molecular sieves) and allyl bromide (19.8 mL, 97%) were added into the system. Polyhydridomethylsiloxane (14.9 mL, Mn 1900 g/mol) were added dropwise. The mixture was stirred and refluxed at 100° C. inside under inert atmosphere (Ar) until complete conversion of the SiH groups was achieved (the reaction was followed by .sup.1H-NMR). The mixture (when necessary) was decolorized by adding activated carbon and an excess of pentane and stirred for 16 h at room temperature. The crude was filtrated trough celite, and the solvents and volatiles were evaporated under vacuum. The obtained product (yield 80-90%) was a colorless, transparent viscous liquid. The molecular weight and structure of the product was confirmed by GPC (M.sub.n=4882 g/mol, PDI 2.190) and NMR spectroscopy.

Example 2: Preparation of 3-(4-bromobutoxy)methylsiloxane

[0081] The procedure was the same as shown in Example 1 except that the inside temperature was 75° C. The obtained product (yield 59%) was a colorless, transparent viscous liquid. The molecular weight and structure of the product was confirmed by GPC (M.sub.n=1616 g/mol, PDI 2.228) and NMR spectroscopy.

Example 3: Preparation of 3-(4-bromobutoxy)methylsiloxane

[0082] The procedure was the same as shown in Example 1 except that the inside temperature was 90° C. The obtained product (yield 81%) was a colorless, transparent viscous liquid. The molecular weight and structure of the product was confirmed by GPC (M.sub.n=5113 g/mol, PDI 2.118) and NMR spectroscopy.

Example 4: Preparation of 3-(4-bromobutoxy)methylsiloxane-co-dimethylsiloxane

[0083] ##STR00005##

[0084] A 250 ml three neck round bottomed flask was degassed under high vacuum (1.sup.−3 mbar) and flushed with argon. Then, 270 μL of Karstedt (2% of Pt in the catalyst, 0.1% mol in the mixture) and THF (40 mL, dried over molecular sieves) were added into the flask under argon atmosphere and stirred at room temperature (20° C.) for a couple of minutes. Then allyl bromide (11.78 mL, 97%) were added into the system. Polyhydridomethylsiloxane-co-polydimethylsiloxane (19.9 mL, Mn 2200 g/mol) were added dropwise. The mixture was stirred and refluxed (oil bath temperature: 100° C.) under inert atmosphere (Ar) until complete conversion of the SiH groups was achieved (the reaction was followed by .sup.1H-NMR). The mixture (when necessary) was decolorized by adding activated carbon and an excess of pentane and stirred for 16 h at room temperature. The crude was filtrated trough celite, and the solvents and volatiles were evaporated under vacuum. The obtained product (yield 80-90%) was a colorless, transparent viscous liquid. The molecular weight and structure of the product was confirmed by GPC (M.sub.n=4495 g/mol, PDI 1.837) and NMR spectroscopy.

Example 5: Preparation of 1-(4-bromobutoxy)-1′,3,3′,5,5′,7,7′-Heptamethylcyclotetrasiloxane

[0085] ##STR00006##

[0086] A 50 ml three neck round bottomed flask was degassed under high vacuum (1.sup.−3 mbar) and flushed with argon. Then, 400 μL of Karstedt (2% of Pt in the catalyst, 0.1% mol in the mixture) and THF (10 mL, dried over molecular sieves) were added into the flask under argon atmosphere and stirred at room temperature (20° C.) for a couple of minutes. Then allyl bromide (1.5 mL, 97%) were added into the system. 1,1′,3,3′,5,5′,7-Heptamethylcyclotetrasiloxane (5.3 mL, Mn 282 g/mol) were added dropwise. The mixture was stirred and refluxed (oil bath temperature: 80° C.) under inert atmosphere (Ar) until complete conversion of the SiH groups was achieved (the reaction was followed by .sup.1H-NMR). The mixture (when necessary) was decolorized by adding activated carbon and an excess of pentane and stirred for 16 h at room temperature. The crude was filtrated trough celite, and the solvents and volatiles were evaporated under vacuum. The obtained product (isolated yield 84%; conversion 89.1%) was a colorless to slightly yellow, transparent low viscous liquid. The molecular weight and structure of the product was confirmed by GPC (M.sub.n=463 g/mol, PDI 1.055) and NMR spectroscopy.

Comparative Example 6 (Adapted from Z. Lu, et al., J. Organomet. Chem. 2012, 697, 51-56)

[0087] ##STR00007##

[0088] A 250 ml three neck round bottomed flask was degassed under high vacuum (1.sup.−3 mbar) and flushed with argon. Then, PdCl.sub.2 (208 mg, 1.6 mol-% in the mixture) and THF (18.5 mL, dried over molecular sieves) were added into the flask under argon atmosphere and stirred at room temperature (20° C.) for a couple of minutes. Then allyl bromide (7.29 mL, 97%) was added into the system. Polyhydridomethylsiloxane (5.0 mL, Mn 1900 g/mol) were added dropwise. The mixture was stirred (oil bath temperature: 50° C.) under inert atmosphere (Ar) for 24 hours. The solvents and volatiles were evaporated under vacuum. The obtained product (yield ˜70%) was a black viscous liquid with precipitation. The molecular weight and structure of the product was confirmed by GPC (M.sub.n=6105 g/mol, PDI 3.872) and NMR spectroscopy.

Comparative Example 7 (Adapted from Z. Lu, et al., J. Organomet. Chem. 2012, 697, 51-56)

[0089] The procedure was the same as shown in Comparative Example 6 except that the temperature was 60° C. For comparison reasons this product was decolorized by adding activated carbon and an excess of pentane and stirred for 16 h at room temperature. The crude was filtrated trough celite, and the solvents and volatiles were evaporated under vacuum. The purified product was yellow colored, which changes during time to black. The molecular weight and structure of the product was confirmed by GPC (M.sub.n=2395 g/mol, PDI 2.678) and NMR spectroscopy.

Comparative Example 8 (Adapted from Z. Lu, et al., J. Organomet. Chem. 2012, 697, 51-56)

[0090] The procedure is the same as shown in Comparative Example 6 except that the temperature was 70° C. For comparison reasons this product was decolorized by adding activated carbon and an excess of pentane and stirred for 16 h at room temperature. The crude was filtrated trough celite, and the solvents and volatiles were evaporated under vacuum. The purified product was yellow colored, which changes during time to black. The molecular weight and structure of the product was confirmed by GPC (M.sub.n=5536 g/mol, PDI 2.483) and NMR spectroscopy.

Comparative Example 9 (Adapted from Z. Lu, et al., J. Organomet. Chem. 2012, 697, 51-56)

[0091] ##STR00008##

[0092] A 50 ml three neck round bottomed flask was degassed under high vacuum (1.sup.−3 mbar) and flushed with argon. Then, PdCl.sub.2 (24 mg, 1.6 mol-% in the mixture) and THF (5 mL, dried over molecular sieves) were added into the flask under argon atmosphere and stirred at room temperature (20° C.) for a couple of minutes. Then allyl bromide (0.84 mL, 97%) was added into the system. 1,1′,3,3′,5,5′,7-Heptamethylcyclotetrasiloxane (3.3 mL, Mn 282 g/mol) were added dropwise. The mixture was stirred (oil bath temperature: 50° C.) under inert atmosphere (Ar) for 24 hours. The solvents and volatiles were evaporated under vacuum. The obtained product (isolated yield 83%; conversion 84.6%) was a clear viscous slightly yellow liquid with black precipitation. The molecular weight and structure of the product was confirmed by GPC (M.sub.n=443 g/mol, PDI 1.042) and NMR spectroscopy.

NMR-Spectroscopy:

[0093] All NMR measurements were done on a Bruker 300 MHz and 400 MHz instrument with deuterated chloroform as solvent. All the samples were measured at room temperature (297 K). The chemical shifts are given in ppm. The calibration of the chemical shifts in 1H spectra was carried out by using the shifts of the deuterated solvents (CDCl3; δH 7.26).

GPC:

[0094] Gel permeation chromatography was carried out using HP1090 II Chromatography with DAD detector (HEWLETT PACKARD) at 40° C. Tetrahydrofuran (THF) was used as an eluent. THF was passed through three PSS SDV gel columns with molecular weight ranges of 102, 103 and 104 g.Math.mol-1 with a flow rate of 0.9 ml.Math.min-1. The calibration of the device was carried out using polystyrene standards.

Elemental Analysis:

[0095] Elemental analyses were performed on a flame atomic absorption spectrometer Perkin-Elmer Analyst 300 (Pd and Pt).

Hazen Factor and Yellowness Index:

[0096] The color values were measured with a LCS III from BYK. The LCS III is a VIS spectrophotometer with a wavelength range of 320 to 1100 nm. The Hazen color value (ISO 6271, also known as “AHPA-method” or Platinum-Cobalt Scale) is defined as mg of platinum per 1 litre of solution. The Yellowness Index was calculated and displayed in accordance with ASTM D 1925 for illuminant C and a 2° standard observer. The instrument was calibrated with distilled water.

[0097] FIG. 1 shows the conversion of SiH groups compared to the time (measured by integration of 1H-NMR spectra) of Example 1 to 3 with different temperatures. The linear shape of the curves proves that the reactions follow a zero-order kinetic with platinum as catalyst. For an overview of reaction kinetics and calculation of activation energies, s. A. Cornish-Bowden, Fundamentals of Enzyme Kinetics, John Wiley & Sons, 2012 or S. K. Upadhyay, Chemical Kinetics and Reaction Dynamics, Springer, 2006 is included as a reference. During the whole reaction time there was no change in the reaction speed. The reaction speed does not depend on the concentration of any monomer. The activation energy can be calculated with the slope of the curve at different temperatures by using the Arrhenius equation. Calculations were done with the temperature inside of the flask. An activation energy of 45.1±2.2 kJ/mol could be calculated.

[0098] FIG. 2 shows the logarithmic plotted conversion of SiH groups compared to the time (measured by integration of 1H-NMR spectra) of Comparative Example 6 to 8 with different temperatures which follows the first order kinetic regime. The reaction needed more time for a full conversion, because the reaction speed depends on the concentration of monomer. The more monomer is converted, the slower the reaction speed is. An activation energy of 77.3±3.1 kJ/mol could be calculated, which is twice as much as the invention.

[0099] Table 1 shows the difficulties of removing the palladium catalyst after the reaction. The amount of platinum in Example 1 is more than 100 times lower than the amount of palladium in Comparative Example 6. The high amount of palladium causes a contamination of the product.

TABLE-US-00001 TABLE 1 Determination of Pt and Pd by elemental analysis Pt [wt-%] Pd [wt-%] Example 1 0.0108 ± 0.0079 Comparative 5.3048 ± 1.4691 Example 6

[0100] Table 2 shows the Hazen Factor and Yellowness Index of Examples 1 and 4 and Comparative Example 6. Compared to Examples 1 and 4, Comparative Example 6 shows a very high Hazen Factor, as well as Yellowness Index, which are more than five times higher. Comparative Example 6 could only be measured in solution (THF, ratio 1:3) as the purified product got darker during time and showed results out of the working area of the instrument. The color changed from yellow to brown and then to dark brown during time. This was caused by the palladium, which cannot be removed with mentioned working-ups. In literature there is no filtration step mentioned (only removing solvent by vacuo), so the palladium was not removed at all.

TABLE-US-00002 TABLE 2 Determination of Hazen Factor and Yellowness Index Hazen Factor Yellowness Index Example 1 112 26.4 Example 4 42 10.6 Comparative 734 103.9 Example 6