Process for preparing tris[3-(alkoxysilyl)propyl] isocyanurates

Abstract

The present invention relates to a process for preparing a tris[3-(alkoxysilyl)propyl] isocyanurate from the group of tris-[3-(trialkoxysilyl)propyl] isocyanurate, tris[3-(alkyldialkoxysilyl)propyl] isocyanurate and tris[3-(dialkylalkoxysilyl)propyl] isocyanurate by hydrosilylation, by in step A initially charging a mixture comprising at least one hydroalkoxysilane from the group of hydrotrialkoxysilane, hydroalkyldialkoxysilane, hydrodialkylalkoxysilane [called H-silane(s) for short], at least one carboxylic acid and a Pt catalyst, heating the mixture to a temperature of 50 to 140 C., in step B adding a mixture of 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione and at least one alcohol to the mixture from step A while mixing, in step C leaving the mixture from step B to react while mixing and in step D working up the product mixture thus obtained.

Claims

1. A process for preparing at least one tris[3-(alkoxysilyl)propyl] isocyanurate selected from the group consisting of tris[3-(trialkoxysilyl)propyl] isocyanurate, tris[3-(alkyldialkoxysilyl)propyl] isocyanurate and tris[3-(dialkylalkoxysilyl)propyl] isocyanurate by hydrosilylation, the process comprising: (A) initially charging a mixture comprising at least one H-silane selected from the group consisting of hydrotrialkoxysilane, hydroalkyldialkoxysilane, and hydrodialkylalkoxysilane, with at least one carboxylic acid and a Pt catalyst, and heating the mixture to a temperature of 50 to 140 C., (B) adding a mixture of 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione and at least one alcohol to the mixture obtained in (A) while mixing, (C) leaving the mixture obtained in (B) to react while mixing and (D) working up the product mixture thus obtained.

2. The process according to claim 1, wherein a molar ratio of the at least one H-silane relative to alcohol is 1:0.005 to 0.3.

3. The process according to claim 1, wherein a molar ratio of the at least one H-silane relative to Pt is 1:110.sup.4 to 110.sup.9.

4. The process according to claim 1, wherein a molar ratio of the at least one H-silane relative to carboxylic acid is 1:110.sup.3 to 3010.sup.3.

5. The process according to claim 1, wherein a molar ratio of the at least one H-silane relative to olefin component is 1:0.1 to 1.

6. The process according to claim 1, wherein the carboxylic acid is at least one selected from the group consisting of benzoic acid, propionic acid, 2,2-dimethylpropionic acid, 3,5-di-tert-butylbenzoic acid, 3,5-di-tert-butyl-4-hydroxybenzoic acid, and acetic acid.

7. The process according to claim 1, wherein the alcohol is at least one selected from the group consisting of C1-C10 alcohols.

8. The process according to claim 1, wherein the at least one H-silane is at least one selected from the group consisting of hydrotrimethoxysilane (TMOS), hydrotriethoxysilane (TEOS), methyldiethoxysilane (DEMS), methyldimethoxysilane (DMMS), dimethylethoxysilane (DMES) and dimethylmethoxysilane (MDMS).

9. The process according to claim 1, wherein the Pt catalyst is at least one catalyst selected from the group consisting of a Karstedt catalyst, hexachloroplatinum(IV) acid, and Pt applied to a solid catalyst support.

10. The process according to claim 1, wherein the alcohol is at least one selected from the group consisting of tert-butanol, ethanol, methanol, benzyl alcohol and diglycol monomethyl ether.

11. The process according to claim 1, wherein the Pt catalyst is a platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex in the form of a Karstedt catalyst in xylene or toluene with a Pt(0) content of 0.5% to 5% by weight, hexachloroplatinum(IV) acid dissolved in acetone, or Pt supported on activated carbon.

12. The process according to claim 1, wherein the Pt catalyst is a platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex in the form of a Karstedt catalyst in xylene or toluene with a Pt(0) content of 0.5% to 5% by weight.

13. The process according to claim 1, wherein the process does not comprise a separate addition of an aliphatic or aromatic hydrocarbon as solvent or diluent.

14. The process according to claim 1, wherein at least 90 mol % of allyl groups in the 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione are converted by hydrosilylation to 3-(alkoxysilyl)propyl groups.

15. The process according to claim 1, further comprising: separating the Pt catalyst from the product mixture obtained in (C) prior to (D) working up the product mixture, thereby obtaining a separated Pt catalyst, and recycling the separated Pt catalyst.

16. The process according to claim 1, wherein (D) working up the product mixture comprises distillation at a temperature of from 45 C. to 150 C. at a pressure of less than 1 bar, thereby removing at least one selected from the group consisting of carboxylic acid, alcohol, H-silane, and olefin.

17. The process according to claim 1, wherein said at least one tris[3-(alkoxysilyl)propyl] isocyanurate is tris[3-(trialkoxysilyl)propyl] isocyanurate.

18. The process according to claim 1, wherein said tris[3-(trialkoxysilyl)propyl] isocyanurate is tris[3-(trimethoxysilyl)propyl] isocyanurate.

19. The process according to claim 1, wherein said tris[3-(trialkoxysilyl)propyl] isocyanurate is tris[3-(triethoxysilyl)propyl] isocyanurate.

Description

EXAMPLES

(1) Analytical Methods:

(2) NMR Measurements:

(3) Instrument: Bruker

(4) Frequency: 500.1 MHz (.sup.1H NMR)

(5) Scans: 32

(6) Temperature: 303 K

(7) Solvent: CDCl.sub.3

(8) Standard: 0.5% TMS (tetramethylsilane)

(9) Explanations are given below with regard to naming of target product and by-products formed in the synthesis with respect to the present .sup.1H NMR evaluations using the example of the structural formula of a tris[3-(trialkoxysilyl)propyl] isocyanurate. The determinations of selectivities with respect to tris[3-(methyldialkoxysilyl)propyl] isocyanurate and tris[3-(dimethylalkoxysilyl)propyl] isocyanurate were conducted analogously and are listed in the tables for Examples 6 and 7.

(10) ##STR00001##
in the target product: functional group S1 (SiCH.sub.2)

(11) ##STR00002##
in the so-called allyl derivative: functional group A1

(12) ##STR00003##
in the so-called propyl derivative: functional group P1

(13) ##STR00004##
in the so-called isopropyl derivative: functional group I1

(14) The experiments were evaluated using the product formed in the hydrosilylation of the 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione. The more allylic double bonds were converted to the target product and the fewer secondary components were formed, the better the product quality and the performance/selectivity of the catalyst system. A high selectivity is very important because the secondary components can be removed by distillation from the target product only with a very high level of complexity, if at all.

(15) The 1H NMR spectra were evaluated using the hydrogen atoms included in the structural formula drawings. The hydrosilylation gives rise to SiCH.sub.2 groups that are characteristic of the target product. The SiCH.sub.2 groups were identified with S1, the allylic groups (CCH.sub.2 group) with A1, the propyl group (C.sub.3H.sub.7 group) with P1 and the isopropyl group with I1. The evaluation of the 1H NMR spectra and the calculation of the functional groups was shown after each experiment in the tables. The evaluated signals from the .sup.1H NMR form triplets (t) for the S1 and P1 group, double doublets (dd) for the A1 group, and doublets (d) for the I1 group.

(16) Chemicals Used:

(17) Karstedt concentrate (platinum(0) 1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, platinum content: 20.37% by weight), HERAEUS

(18) Acetone, pure, LABC Labortechnik

(19) Hexachloroplatinum(IV) acid hexahydrate, platinum content 40% by weight, HERAEUS

(20) Platinum-activated carbon, hydrogenation catalyst, platinum content 10% by weight, MERCK

(21) Benzyl alcohol, puriss, SIGMA ALDRICH

(22) Diethylene glycol monomethyl ether >98% by weight, MERCK

(23) Xylene Technical, VWR Chemicals

(24) Dynasylan TMOS (trimethoxysilane), EVONIK Industries

(25) Dynasylan TEOS-H (triethoxysilane), EVONIK Industries

(26) Dynasylan DEMS (methyldiethoxysilane), EVONIK Industries

(27) Dynasylan DMES (dimethylethoxysilane), EVONIK Industries

(28) TIACROS (1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione), EVONIK Industries

(29) Benzoic acid 99.5% by weight, ROTH

(30) 3,5-Di-tert-butylbenzoic acid >98.0% by weight, TOKYO CHEMICAL INDUSTRY

(31) 3,5-Di-tert-butyl-4-hydroxybenzoic acid, >98.0% by weight, TOKYO CHEMICAL INDUSTRY

(32) Acetic acid, 99% by weight, SIGMA-ALDRICH

(33) Methanol 99.5% by weight, MERCK

(34) Ethanol 99.8% by weight, ROTH

(35) tert-Butanol, 99.0% by weight (for synthesis), ROTH

(36) Chloroform-d1 (CDCl.sub.3)+0.5% by weight of TMS, DEUTERO

(37) Benzene-d6, DEUTERO

(38) Tetramethylsilane, DEUTERO

(39) Preparation of Karstedt-Catalyst No. 1 with Platinum Content 2% by Weight in Xylene:

(40) In a 0.2 l glass bottle, 9.8 g of Karstedt concentrate (platinum(0) 1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, platinum content 20.37%) were mixed with 90.2 g of xylene.

(41) Preparation of Karstedt-Catalyst No. 2 with Platinum Content 2% by Weight in Toluene:

(42) In a 0.2 l glass bottle, 9.8 g of Karstedt concentrate (platinum(0) 1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, platinum content 20.37% by weight) were mixed with 90.2 g of toluene.

(43) Preparation of Karstedt-Catalyst No. 3 with Platinum Content 0.4% by Weight:

(44) In a 0.1 l glass bottle, 196.4 mg of Karstedt concentrate (platinum(0) 1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, platinum content 20.37% by weight) were mixed with 9.8 g of toluene.

(45) Preparation of Catalyst 4 from Hexachloroplatinum(IV) Acid Hexahydrate Solution in Acetone with Pt Content 2.34% by Weight:

(46) In a 12 l plastic vessel, 530 g of H.sub.2PtCl.sub.6x6H.sub.2O were dissolved in 9.8 l of acetone. The catalyst solution thus prepared was used after maturing for 8 weeks.

COMMENT ON THE COMPARATIVE EXAMPLES WHICH FOLLOW

(47) The synthesis in ampoules described in U.S. Pat. No. 5,986,124 cannot be conducted on the industrial scale. In order that the experiments can be better compared with the inventive examples, the experiments were conducted in a stirred tank or flask. Furthermore, in the examples in U.S. Pat. No. 5,986,124, different unsaturated compounds were used, and so a direct comparison with the present invention would not be possible; thus, TAICROS was used in the comparative examples which follow.

Comparative Example 1: Based on Example 1 from U.S. Pat. No. 5,986,124

(48) 0.2003 mol (24.5 g) of Dynasylan TMOS, 0.1 mi of Catalyst No. 1, a further 40.0 g of toluene as additional solvent/diluent, 0.0665 mol (16.8 g) of TAICROS and 0.4 ml of acetic acid were initially charged in a 0.25 l stirred apparatus with jacketed coil condenser and stirred in an oil bath heated to 53-55 C. for 2.5 hours. This gave 79.9 g of incompletely converted and colourless bottom product. The volatile components were not removed.

(49) Evaluation of the .sup.1H NMR spectrum with regard to Comparative Example 1:

(50) TABLE-US-00001 Solvent: N CDCl.sub.3 + 0.5% Signal at Number of TMS [ppm] Integral I protons I/N % (mol) S1 0.64 100.00 2 50.00 45.8 A1 5.27 117.28 2 58.64 53.7 P1 0.93 0.81 3 0.27 0.3 I1 1.00 0.61 3 0.20 0.2

(51) Result: 45.8% of the allyl groups were converted by hydrosilylation to trimethoxysilylalkyl groups (cf. S1). 53.7% of the allyl groups (A1) have not been converted, and 0.3% propyl groups (P1) and 0.2% isopropyl groups (I1) that contaminate the product have formed. The reaction is incomplete.

Comparative Example 2: Based on Example 1 from U.S. Pat. No. 5,986,124

(52) 0.2003 mol (32.9 g) of Dynasylan TEOS-H, 0.1 ml of Catalyst No. 3, a further 40.0 g of toluene as additional solvent/diluent, 0.0665 mol (16.6 g) of TAICROS and 0.4 ml of acetic acid were initially charged in a 0.25 l stirred apparatus with reflux condenser and stirred in an oil bath heated to 50-57 C. for 2.5 hours. This gave 88.2 g of incompletely converted and colourless bottom product. The volatile components were not removed.

(53) Evaluation of the .sup.1H NMR spectrum with regard to Comparative Example 2:

(54) TABLE-US-00002 Solvent: N CDCl.sub.3 + 0.5% Signal at Number of TMS [ppm] Integral I protons I/N % (mol) S1 0.64 100.00 2 50.00 86.2 A1 5.26 14.59 2 7.30 12.6 P1 0.94 0.33 3 0.33 0.6 I1 1.06 0.35 3 0.35 0.6

(55) Result: 86.2% of the allyl groups were converted by hydrosilylation to trimethoxysilylalkyl groups (cf. S1). 12.6% of the allyl groups (A1) have not been converted, and 0.6% propyl groups (P1) and 0.6% isopropyl groups (I1) that contaminate the product have formed. The reaction is incomplete.

Comparative Example 3: With Acetic Acid Only, No Addition of Alcohol

(56) 1.2 mol of DYNASYLAN TMOS and 0.2 g of Catalyst No. 1 (corresponding to 0.0205 mmol of Pt) were initially charged in a 0.5 l stirred apparatus with reflux condenser, metering apparatus. At a temperature of 76-91 C., a mixture consisting of 0.33 mol of TAICROS and 6.77 mmol of acetic acid was metered in within 1 h. Thereafter, the mixture was left to react further at about 87-92 C. for about 1 further hour. Subsequently, 55.0 g of low boilers were removed at 90-120 C. and a pressure of <0.1 mbar. This gave 170.7 g of incompletely converted, colourless bottom product.

(57) Evaluation of the .sup.1H NMR spectrum with regard to Comparative Example 3:

(58) TABLE-US-00003 Solvent: N CDCl.sub.3 + 0.5% Signal at Number of TMS [ppm] Integral I protons I/N % (mol) S1 0.66 100.00 2 50.00 73.8 A1 5.25 34.79 2 17.40 25.7 P1 0.94 0.61 3 0.20 0.3 I1 1.01 0.43 3 0.14 0.2

(59) Result: 73.8% of the allyl groups were converted by hydrosilylation to trimethoxysilylalkyl groups (cf. S1). 25.7% of the allyl groups (A1) have not been converted, and 0.3% propyl groups (P1) and 0.2% isopropyl groups (I1) that contaminate the product have formed. The reaction is incomplete.

Comparative Example 4

(60) 1.2 mol of Dynasylan TMOS, 0.2 g of Karstedt catalyst (corresponding to 0.0205 mmol of Pt), 34.38 mmol of methanol and 6.55 mmol of benzoic acid were initially charged in a 0.5 l stirred apparatus with reflux condenser, metering apparatus. At a temperature of 73-82 C., 0.33 mol of TAICROS was metered in within 1 hour. Thereafter, the mixture was left to react further at 81 C. for another 1 hour. Subsequently, 89.5 g of low boilers were removed at 35-127 C. and a pressure of <0.1 mbar. This gave 134.2 g of incompletely converted and colourless bottom product.

(61) Evaluation of the .sup.1H NMR spectrum from Comparative Example 4:

(62) TABLE-US-00004 Solvent: N CDCl.sub.3 + 0.5% Signal at Number of TMS [ppm] Integral protons I/N % (mol) S1 0.66 100.00 2 50.00 42.5 A1 5.25 134.10 2 67.05 57.0 P1 0.94 1.24 3 0.41 0.4 I1 1.01 0.36 3 0.12 0.1

(63) Result: 42.5% of the allyl groups were converted by hydrosilylation with TMOS to trimethoxysilylalkyl groups (cf. S1). 57.0% of the allyl groups (A1) were not converted. 0.4% propyl groups (P1) and 0.1% isopropyl groups (I1) that contaminate the product were formed. The conversion of the allyl groups is incomplete, and only a low level of by-products is formed.

Comparative Example 5

(64) 1.2 mol of Dynasylan TMOS, 0.2 g of Karstedt catalyst (corresponding to 0.0205 mmol of Pt) and 34.38 mmol of methanol were initially charged in a 0.5 l stirred apparatus with reflux condenser, metering apparatus. At a temperature of 70-87 C., a mixture consisting of 0.33 mol of TAICROS and 6.55 mmol of benzoic acid was metered in within 1 hour. Thereafter, the mixture was left to react further at 81 C. for another 1 hour. Subsequently, 41.5 g of low boilers were removed at 61-121 C. and a pressure of <0.1 mbar. This gave 183.0 g of incompletely converted and colourless bottom product.

(65) TABLE-US-00005 Evaluation of the 1H NMR spectrum from Comparative Example 5: Solvent: N CDCl.sub.3 + 0.5% Signal at Number of TMS [ppm] Integral protons I/N % (mol) S1 0.66 100.0 2 50.00 81.5 A1 5.25 21.75 2 10.87 17.7 P1 0.94 1.09 3 0.36 0.6 I1 1.01 0.38 3 0.13 0.2

(66) Result: 81.5% of the allyl groups were converted by hydrosilylation with TMOS to trimethoxysilylalkyl groups (cf. S1). 17.7% of the allyl groups (A1) were not converted. 0.6% propyl groups (P1) and 0.2% isopropyl groups (I1) that contaminate the product were formed. The conversion of the allyl groups is incomplete, and only a low level of by-products is formed.

Comparative Example 6

(67) 0.33 mol (83.1 g) of TAICROS, 0.2 g of Catalyst No. 1 (corresponding to 0.0205 mmol of Pt) and 6.79 mmol (1.7 g) of 3,5-di-tert-butyl-4-hydroxybenzoic acid were initially charged in a 0.5 l stirred apparatus with reflux condenser, metering apparatus. At a temperature of 91-111 C., 1.2 mol (146.6 g) of Dynasylan TMOS were supposed to be metered in. The hydrosilylation is highly exothermic and, after metered addition of 18 g of Dynasylan TMOS, the temperature had already risen from 91 to 97 C. within 9 minutes. Once a further 72 g of Dynasylan TMOS had been metered in within 27 minutes and the temperature had risen to 108 C., it was not possible to detect any exothermicity in the course of further addition of Dynasylan TMOS. The reaction mixture cooled down from 108 to 89 C. within a few minutes. The experiment was therefore stopped after metered addition of a total of 90 g of Dynasylan TMOS; in other words, the reaction stopped and the conversion in this procedure thus remained correspondingly incomplete. 68 g of Dynasylan TMOS were not metered in.

(68) Note:

(69) The present comparative experiments for preparation of tris[3-(alkoxysilyl)propyl] isocyanurates by hydrosilylation of 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (TAICROS) in the presence of a Pt catalyst system composed of Pt catalyst and carboxylic acid show that a comparatively low conversion of the double bond of well below 90 mol % is discovered when a mixture of H-silane, Pt catalyst, carboxylic acid and TAICROS is used, heated and reacted as such H-silane and Pt catalyst are initially charged and heated and a mixture of TAICROS and carboxylic acid is metered in H-silane, Pt catalyst and alcohol are initially charged and heated and a mixture of TAICROS and carboxylic acid is metered in H-silane, Pt catalyst, carboxylic acid and alcohol are initially charged and heated and TAICROS is metered in or TAICROS, Pt catalyst and carboxylic acid are initially charged and heated and H-silane is metered in.

Example 1

(70) 1.2 mol of Dynasylan TMOS, 0.2 g of Karstedt catalyst No. 1 (corresponding to 0.0205 mmol of Pt) and 6.55 mmol of benzoic acid were initially charged in a 0.5 l stirred apparatus with reflux condenser, metering apparatus. At a temperature of 71-82 C., a mixture consisting of 0.33 mol of TAICROS and 50.0 mmol of methanol was metered in within 1 hour. Thereafter, the mixture was left to react further at 81 C. for another hour and then a .sup.1H NMR spectrum of a sample of the liquid phase was measured.

(71) Evaluation of the .sup.1H NMR spectrum with regard to liquid phase sample of Example 1:

(72) TABLE-US-00006 Solvent: N CDCl.sub.3 + 0.5% Signal at Number of TMS [ppm] Integral protons I/N % (mol) S1 0.66 100.0 2 50.00 98.1 A1 5.25 0.05 2 0.03 0.1 P1 0.94 2.20 3 0.73 1.4 I1 1.01 0.57 3 0.19 0.4

(73) Result: 98.1% of the allyl groups were converted by hydrosilylation with TMOS to trimethoxysilylalkyl groups. 0.1% of the allyl groups (A1) were not converted. 1.4% propyl groups (P1) and 0.4% isopropyl groups (I1) that contaminate the product were formed. The conversion of the allyl groups is not virtually complete, and only a low level of by-products is formed. Only traces of incompletely converted allyl groups are present.