METHOD FOR PRODUCING POLYSULPHANE-SILANES BY MEANS OF PHASE TRANSFER CATALYSIS

Abstract

A method for producing polysulphane-silanes of formula (I): (R.sup.1).sub.3-mR.sup.2.sub.mSi—R.sup.3—S.sub.x—R.sup.3—SiR.sup.2.sub.m(OR.sup.1).sub.3-m by reacting at least one silane of formula (II): (R.sup.1).sub.3-mR.sup.2.sub.mSi—R.sup.3-Hal with M(SH).sub.y and/or M.sub.zS and sulphur, in the presence of a phase transfer catalyst of formula (III), wherein at least one carrier-vapour distillation and/or ozone treatment is performed during or after the reaction.

Claims

1. A process for preparing polysulfane silanes of the formula I
(R.sup.1).sub.3-mR.sup.2.sub.mSi—R.sup.3—S.sub.x—R.sup.3—SiR.sup.2.sub.m(R.sup.1).sub.3-m  I where R.sup.1 are the same or different and are a C1-C10-alkoxy group, phenoxy group, or alkyl polyether group —(R′—O).sub.rR″ where R′ is the same or different and is a branched or unbranched, saturated or unsaturated, aliphatic, aromatic, or mixed aliphatic/aromatic divalent C1-C30 hydrocarbon group, r is an integer from 1 to 30 and R″ is unsubstituted or substituted, branched or unbranched, monovalent alkyl, alkenyl, aryl, or aralkyl group, R.sup.2 are the same or different and are C6-C20 aryl groups, C1-C10 alkyl groups, C2-C20 alkenyl groups, C7-C20 aralkyl groups, or halogen, R.sup.3 are the same or different and are a branched or unbranched, saturated or unsaturated, aliphatic, aromatic, or mixed aliphatic/aromatic divalent C1-C30 hydrocarbon group, and m is the same or different and is 0, 1, 2 or 3, x is 2-10, by reacting at least one silane of the formula II
(R.sup.1).sub.3-mR.sup.2.sub.mSi—R.sup.3-Hal  II where Hal is Cl, Br, or I with M(SH).sub.y and/or M.sub.zS and/or M.sub.gS.sub.h and/or sulfur, where y=1 or 2, and M=Na or K when y=1, and M=Ca or Mg when y=2, and z=1 or 2, and M=Ca or Mg when z=1, and M=Na or K when z=2, and g=1 or 2, and M=Ca or Mg when g=1, and M=Na or K when g=2, h=natural number from 1 to 10, in the presence of a base, an aqueous phase and a phase transfer catalyst of the formula III ##STR00002## where Y is an element of main group 5, R.sup.4, R.sup.5, R.sup.6.sub.1 and R.sup.7 are identical or different and are —(CH.sub.2).sub.kCH.sub.3 alkyl radicals, with k=0-9, or there are one or two ring closures —(CH.sub.2).sub.n— with n=2-5, preferably n=4, between two substituents selected from the R.sup.4, R.sup.5, R.sup.6, and R.sup.7 groups, and X.sup.− is F.sup.−, I.sup.−, Cl.sup.−, Br.sup.−, ClO.sub.4.sup.−, PF.sub.6.sup.−, BF.sub.4.sup.−, (C.sub.6H.sub.5).sub.4B.sup.−, H.sub.2PO.sub.4.sup.−, CH.sub.3SO.sub.3.sup.−, C.sub.6H.sub.5SO.sub.3.sup.−, HSO.sub.4.sup.−, NO.sub.3.sup.−, or ½ SO.sub.4.sup.2−, wherein at least one carrier vapour distillation and/or ozone treatment is performed during or after the reaction.

2. The process for preparing polysulfane silanes of the formula I according to claim 1, wherein R.sup.1 is ethoxy, m=0, and R.sup.3═(CH.sub.2).sub.3.

3. The process for preparing polysulfane silanes of the formula I according to claim 1, wherein Hal=Cl.

4. The process for preparing polysulfane silanes of the formula I according to claim 1, wherein M=Na.

5. The process for preparing polysulfane silanes of the formula I according to claim 1, wherein the base used is M.sub.3-wCO.sub.3, M(OH).sub.w, M.sub.3-w(HPO.sub.4), M(H.sub.2PO.sub.4).sub.w, M.sub.3(PO.sub.4).sub.w, where w is 1 or 2, and M=Na or K when w=1, and M=Ca or Mg when w=2.

6. The process for preparing polysulfane silanes of the formula I according to claim 5, wherein the base used is Na.sub.2CO.sub.3 or NaOH.

7. The process for preparing polysulfane silanes of the formula I according to claim 1, wherein the reaction is conducted at temperatures from 25° C. to 200° C.

8. The process for preparing polysulfane silanes of the formula I according to claim 1, wherein the phase transfer catalyst of the formula III and the silane of the formula II are added to the aqueous phase.

9. The process for preparing polysulfane silanes of the formula I according to claim 1, wherein a charcoal aftertreatment is additionally conducted.

10. The process for preparing polysulfane silanes of the formula I according to claim 1, wherein M(SH).sub.y and/or M.sub.zS and/or M.sub.gS.sub.h are prepared from MOH and sulfur in situ.

11. (canceled)

Description

EXAMPLES

Comparative Example 1: Preparation of bis(triethoxysilylpropyl)disulfane

[0429] For preparation of bis(triethoxysilylpropyl)disulfane by means of phase transfer catalysis, a mixture of sodium carbonate (189 g, 1.8 mol, 1.2 equiv.), sodium hydrogensulfide (225 g, 1.6 mol, 1.0 equiv., 40.0% aqueous solution) and water (572 g, 32 mol, 21 equiv.) was heated to 72° C. The reaction mixture was first stirred at 72° C. for 10 min, then sulfur (55 g, 1.7 mol, 1.1 equiv.) was added to the mixture, which was stirred at 72° C. for a further 45 minutes. Tetra-n-butylammonium bromide (20 g, 0.03 mol, 0.02 equiv., 50% aqueous solution) and (3-chloropropyl)triethoxysilane (743 g, 3.1 mol, 2.0 equiv.) were added successively to the reaction mixture at 70-80° C. The suspension was stirred at 75° C. for 3 hours (GC conversion after 1 hour=98%). After the reaction had ended, water (589 g) was added and the phases were separated at 71° C. The crude product (793 g) was obtained as a yellow liquid. Low boilers were then removed by means of a thin-film evaporator at 140° C. and 10 mbar abs., such that the bis(triethoxysilylpropyl)disulfane was isolated as bottom product and then filtered.

Comparative Example 2: Preparation of bis(triethoxysilylpropyl)tetrasulfane

[0430] For preparation of bis(triethoxysilylpropyl)tetrasulfane by means of phase transfer catalysis, a mixture of sodium hydroxide (81 g, 1.0 mol, 1.0 equiv.), sodium hydrogensulfide (284 g, 2.0 mol, 2.0 equiv., 40.0% aqueous solution) and water (158 g, 8.8 mol, 4.2 equiv.) was heated to 70° C. The reaction mixture was first stirred at 70° C. for 10 min, then sulfur (184 g, 5.7 mol, 2.8 equiv.) was added to the mixture, which was stirred at 72° C. for a further 15 minutes. Tetra-n-butylammonium bromide (17 g, 0.03 mol, 0.01 equiv., 50% aqueous solution) and (3-chloropropyl)triethoxysilane (999 g, 4.2 mol, 2.0 equiv.) were added successively to the reaction mixture at 70-80° C. The suspension was stirred at 75° C. for 2 hours (GC conversion after 2 hours=98%). After the reaction had ended, water (249 g) was added and the phases were separated at 71° C. The crude product (1.1 kg) was obtained as a yellow liquid. Low boilers were then removed by means of a thin-film evaporator at 140° C. and 10 mbar abs., such that the bis(triethoxysilylpropyl)tetrasulfane was isolated as bottom product and then filtered.

Example 1: Carrier Vapour Distillation of bis(triethoxysilylpropyl)disulfane

[0431] The bis(triethoxysilylpropyl)disulfane from Comparative Example 1 was preheated to 97° C. and applied at 30 ml/min at the top of a column that had been heated to 160° C. and evacuated to 20 mbar abs. Steam and nitrogen were fed in from the lower portion of the column in countercurrent, and were distilled off by means of a distillation system in the upper portion of the column. The distillate was enriched in tributylamine, and the bis(triethoxysilylpropyl)disulfane was isolated as a purified bottom product. [0432] Column details: fill height 75 cm and internal diameter=25 mm, filled with porcelain saddles (diameter 6 mm) [0433] GC before distillation: 0.54% tributylamine (degradation product of the PTC catalyst) [0434] GC after distillation: 0.01% tributylamine

Example 2: Carrier Vapour Distillation of bis(triethoxysilylpropyl)tetrasulfane

[0435] The bis(triethoxysilylpropyl)tetrasulfane from Comparative Example 2 was preheated to 97° C. and applied at 30 ml/min at the top of a column that had been heated to 160° C. and evacuated to 20 mbar abs. Steam and nitrogen were fed in from the lower portion of the column in countercurrent, and were distilled off by means of a distillation system in the upper portion of the column. The distillate was enriched in tributylamine, and the bis(triethoxysilylpropyl)tetrasulfane was isolated as a purified bottom product. [0436] Column details: fill height 75 cm and internal diameter=25 mm, filled with porcelain saddles (diameter 6 mm) [0437] GC before distillation: 0.33% tributylamine (degradation product of the PTC catalyst) [0438] GC after distillation: <0.01% tributylamine

Example 3: Carrier Vapour Distillation of bis(triethoxysilylpropyl)disulfane

[0439] Multiple batches of bis(triethoxysilylpropyl)disulfane that had been prepared according to Comparative Example 1 were preheated to 120° C. and applied from the top at 20 kg/h to a column that had been heated to 120° C. and evacuated to 35 mbar abs. Steam (4 kg/h) and nitrogen (1 nL/min) were fed in from the lower portion of the column in countercurrent, and were distilled off by means of a distillation system in the upper portion of the column. The distillate was enriched in tributylamine, and the bis(triethoxysilylpropyl)disulfane was isolated as a purified bottom product. [0440] Column details: DN80 rectification column: 4×1 m glass column sections with compensation heating, packed with a Montz A3-500 fabric packing, were used. [0441] GC before distillation: 0.56% tributylamine (degradation product of the PTC catalyst) [0442] GC after distillation: <0.01% tributylamine

Example 4: Carrier Vapour Distillation of bis(triethoxysilylpropyl)tetrasulfane

[0443] Multiple batches of bis(triethoxysilylpropyl)tetrasulfane that had been prepared according to Comparative Example 2 were preheated to 140° C. and applied from the top at 25 kg/h to a column that had been heated to 140° C. and evacuated to 35 mbar abs. Steam (3 kg/h) and nitrogen (0.5 nL/min) were fed in from the lower portion of the column in countercurrent, and were distilled off by means of a distillation system in the upper portion of the column. The distillate was enriched in tributylamine, and the bis(triethoxysilylpropyl)tetrasulfane was isolated as a purified bottom product. [0444] Column details: DN80 rectification column: 4×1 m glass column sections with compensation heating, packed with a Montz A3-500 fabric packing. [0445] GC before distillation: 0.38% tributylamine (degradation product of the PTC catalyst) [0446] GC after distillation: <0.01% tributylamine

Example 5: Ozone Treatment of bis(triethoxysilylpropyl)disulfane

[0447] A bottle-shaped 250 ml reaction apparatus was charged with 150 g of bis(triethoxysilylpropyl)disulfane from Comparative Example 1, which was stirred at room temperature. By means of a hose, over a period of 2 hours, an ozone/air mixture produced in an ozone generator with an ozone constituent of about 260 mg of ozone was passed through the crude product. Low boilers were then removed by means of a thin-film evaporator at 140° C. and 13 mbar abs., such that the bis(triethoxysilylpropyl)disulfane was isolated as bottom product. [0448] Output of the ozone generator: about 130 mg/h in air [0449] GC before ozone treatment: 0.1% ethanol, 0.16% tributylamine (degradation product of the PTC catalyst) [0450] GC after ozone treatment: 0.1% ethanol, <0.01% tributylamine [0451] GC after thin-film evaporator 0.02% ethanol, <0.01% tributylamine

Example 6: Ozone Treatment of bis(triethoxysilylpropyl)tetrasulfane

[0452] A bottle-shaped 250 ml reaction apparatus was charged with 150 g of bis(triethoxysilylpropyl)tetrasulfane from Comparative Example 2, which was stirred at room temperature. By means of a hose, over a period of 1 h, an ozone/air mixture produced in an ozone generator with an ozone constituent of about 130 mg of ozone was passed through the crude product.

[0453] Low boilers were then removed by means of a thin-film evaporator at 140° C. and 13 mbar abs., such that the bis(triethoxysilylpropyl)tetrasulfane was isolated as bottom product. [0454] Output of the ozone generator: about 130 mg/h in air [0455] GC before ozone treatment: 0.2% ethanol, 0.15% tributylamine (degradation product of the PTC catalyst) [0456] GC after ozone treatment: 0.04% ethanol, <0.01% tributylamine [0457] GC after thin-film evaporator 0.03% ethanol, <0.01% tributylamine

Example 7: Activated Charcoal Treatment of bis(triethoxysilylpropyl)disulfane

[0458] Bis(triethoxysilylpropyl)disulfane was treated by means of the process according to the invention by carrier vapour distillation according to Example 1. In the subsequent step, the bis(triethoxysilylpropyl)disulfane from Example 1 was admixed in each case with 1% or 2% activated charcoal at room temperature and then filtered. [0459] GC before activated charcoal: 0.01% tributylamine [0460] GC after 1% activated charcoal: <0.01% tributylamine [0461] GC after 2% activated charcoal: <0.01% tributylamine

Example 8: Activated Charcoal Treatment of bis(triethoxysilylpropyl)tetrasulfane

[0462] Bis(triethoxysilylpropyl)tetrasulfane was treated by means of distillation according to the invention by carrier vapour distillation according to Example 2. In the subsequent step, the bis(triethoxysilylpropyl)tetrasulfane from Example 2 was admixed in each case with 1% or 2% activated charcoal at room temperature and then filtered. [0463] GC before activated charcoal: 0.01% tributylamine [0464] GC after 1% activated charcoal: <0.01% tributylamine [0465] GC after 2% activated charcoal: <0.01% tributylamine

Example 9: Stability Tests on bis(triethoxysilylpropyl)tetrasulfane with 0.28% tributylamine

[0466] Comparative Example 2 was subjected to a prolonged storage stability test. The bis(triethoxysilylpropyl)tetrasulfane was analysed by HPLC at defined time intervals. S2 and S3 content after the production are unstable. [0467] HPLC after about 1 day: S2 content: 17% by wt., S3 content: 31% by wt., S.sub.4-S.sub.10 content: 52% by wt. [0468] HPLC after about 7 months: S2 content: 16% by wt., S3 content: 32% by wt., S.sub.4-S.sub.10 content: 52% by wt. [0469] HPLC after about 15 months: S2 content: 15% by wt., S3 content: 33% by wt., S.sub.4-S.sub.10 content: 52% by wt.

Example 10: Stability Tests on bis(triethoxysilylpropyl)tetrasulfane with <0.01% tributylamine

[0470] Inventive Example 2 was subjected to a prolonged storage stability test. The bis(triethoxysilylpropyl)tetrasulfane was analysed by HPLC at defined time intervals. S2 and S3 content after the production are stable. [0471] HPLC after about 1 day: S2 content: 18% by wt, S3 content: 31% by wt, S.sub.4-S.sub.10 content: 51% by wt. [0472] HPLC after about 1 month: S2 content: 18% by wt, S3 content: 31% by wt, S.sub.4-S.sub.10 content: 51% by wt. [0473] HPLC after about 6 months: S2 content: 18% by wt, S3 content: 31% by wt, S.sub.4-S.sub.10 content: 51% by wt.

Example 11: Stability Tests on bis(triethoxysilylpropyl)tetrasulfane with <0.01% tributylamine

[0474] Inventive Example 5 was subjected to a prolonged storage stability test. The bis(triethoxysilylpropyl)tetrasulfane was analysed by HPLC at defined time intervals. S2 and S3 content after the production are stable. [0475] HPLC after about 1 day: S2 content: 17% by wt., S3 content: 31% by wt., S.sub.4-S.sub.10 content: 52% by wt. [0476] HPLC after about 5 months: S2 content: 17% by wt., S3 content: 31% by wt., S.sub.4-S.sub.10 content: 52% by wt. [0477] HPLC after about 23 months: S2 content: 17% by wt., S3 content: 31% by wt., S.sub.4-S.sub.10 content: 52% by wt.