PROCESS FOR PREPARING A COMPOSITION CONTAINING 2-PROPYLHEPTYL SILICATE

Abstract

A composition containing 2-propylheptyl silicate is obtained by heating ethyl silicate with an amount of 2-propylheptanol used in excess in the presence of titanium tetrabutoxide as catalyst to a temperature of not more than 220° C. while mixing, allowing them to react and, after the reaction, removing ethanol and excess 2-propylheptanol from the reaction mixture by distillation and obtaining the product, to obtain the composition comprising 2-propylheptyl silicate.

Claims

1. A process for preparing a composition comprising 2-propylheptyl silicate, said process comprising: heating ethyl silicate with an amount of 2-propylheptanol used in excess in the presence of titanium tetrabutoxide as catalyst to a temperature of not more than 220° C. while mixing, allowing them to react and, after the reaction, removing ethanol and excess 2-propylheptanol from the reaction mixture by distillation and obtaining the product, to obtain the composition comprising 2-propylheptyl silicate.

2. The process according to claim 1, wherein ethyl silicate and 2-propylheptanol are used in a weight ratio of 1:1.1 to 10.

3. The process according to claim 1, wherein 0.01% to 0.5% by weight of titanium tetrabutoxide is used, based on the amount of ethyl silicate used.

4. The process according to claim 1, wherein the reaction is conducted at a temperature of 150 to 222° C.

5. The process according to claim 1, wherein the reaction is conducted over a period of 12 to 60 hours.

6. The process according to claim 1, wherein the transesterification is conducted with a yield of ≧95%.

7. The process according to claim 1, wherein a reaction product having a 2-propylheptyl silicate content of ≧90% by weight is obtained.

8. A composition having a 2-propylheptyl silicate content of ≧90% by weight, obtainable according to claim 1.

9. The composition according to claim 8, having a 2-propylheptyl silicate content of ≧95% by weight.

10. The composition according to claim 8, having an ethanol content of ≦1% by weight, based on the composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention thus provides a process for preparing a composition containing 2-propylheptyl silicate, by heating ethyl silicate with an amount of 2-propylheptanol used in excess in the presence of titanium tetrabutoxide as catalyst to a temperature of ≦220° C. while mixing, allowing them to react and, after the reaction, removing ethanol and excess 2-propylheptanol from the reaction mixture by distillation and obtaining the product.

[0010] Advantageously, in the process according to the invention, ethyl silicate and 2-propylheptanol are used in a weight ratio of 1:1.1 to 10, preferably 1:1.5 to 5, more preferably 1:3.4.

[0011] Moreover, in the process according to the invention, advantageously 0.01% to 0.5% by weight, preferably from 0.05% to 0.2% by weight and more preferably 0.1% by weight of titanium tetrabutoxide, based on the amount of 2-propylheptyl silicate used, is used.

[0012] Suitably, in the process according to the invention, the reaction is conducted at a temperature of 150 to 222° C., preferably of 170 to 221° C., more preferably at 200 to 220° C., and over a period of 12 to 60 hours, preferably of 16 to 48 hours.

[0013] In general, the process according to the invention is conducted as follows:

[0014] In general, a mixture of ethyl silicate and a relative excess of 2-propylheptanol in terms of weight, and also a catalytic amount of titanium tetrabutoxide, is initially charged in a suitable reaction apparatus (for example reaction vessel with feeds for reactant metering, stirrer, heating, temperature control/regulation, reflux condenser and bridge with receiver), the mixture is heated while stirring, preferably to a temperature just below the boiling range of 2-propylheptanol, especially at a temperature in the region of 205 to 220° C., the mixture is allowed to react for a sufficiently long period, preferably of 12 to 48 hours, and then the volatile components still present in the reaction mixture/product mixture thus obtained, such as ethanol, and excess 2-propylheptanol, suitably under reduced pressure, are suitably distilled, in order to work up the reaction mixture/product mixture by means of distillation and hence obtain the product. For example, for performance of the distillation, the reaction mixture/product mixture present after a reaction can be transferred from the reaction vessel into a separate distillation unit and be worked up by means of distillation. In addition, it is possible to apply vacuum in the course of the distillation, i.e. to distill under reduced pressure, and optionally additionally to pass nitrogen through the product/product mixture present in the bottom of the distillation apparatus. The product, the composition according to the invention, is thus advantageously obtained as a colourless to yellowish, slightly viscous liquid in the bottom of the distillation apparatus used.

[0015] Surprisingly, the performance of the process according to the invention, in a particularly advantageous manner, achieves virtually complete transesterification with a yield of ≧95% and hence favourably makes it possible to provide a corresponding reaction product and, by the process according to the invention, advantageously makes it possible to obtain a composition having a high 2-propylheptyl silicate content of ≧90% by weight, preferably ≧95% by weight.

[0016] The present invention therefore also provides compositions having a 2-propylheptyl silicate content of ≧90% by weight, preferably ≧95% by weight, obtainable by the process according to the invention.

[0017] The invention further provides a composition or composition prepared in accordance with the invention having a 2-propylheptyl silicate content of ≧90% by weight, preferably ≧95% by weight, based on the composition. In addition, a composition according to the invention or composition prepared in accordance with the invention preferably has an ethanol content of ≦1% by weight, preferably ≦0.5% by weight down to the detection limit, based on the composition, and is thus also notable from an environmental point of view additionally for a very low proportion of VOCs (volatile organic compounds).

[0018] It is thus advantageously possible to use compositions according to the invention, for Example—but not exclusively—as coupling reagent in the preparation of functional polymers, such as butadiene rubber, or in solution styrene-butadiene rubber.

[0019] The present invention is elucidated in detail by the examples which follow, without restricting the subject-matter of the invention:

[0020] Having generally described this invention, a further understanding can be obtained by reference to certain specific examples which are provided herein for purposes of illustration only, and are not intended to be limiting unless otherwise specified.

EXAMPLES

Chemicals Used

[0021] Dynasylan® 40 (ethyl silicate), Evonik Resource Efficiency GmbH

[0022] Titanium tetrabutoxide, Sigma-Aldrich

[0023] 2-Propylheptanol, Evonik Performance Materials GmbH

Analytical Methods

[0024] NMR measurements:

[0025] Instrument: Bruker

[0026] Frequency: 100.6 MHz (.sup.13C-NMR)

[0027] Scans: 1024 (.sup.13C-NMR)

[0028] Temperature: 296 K

[0029] Solvent: CDCl.sub.3

[0030] Standard: tetramethylsilane

[0031] Gas chromatography determination of alcohol:

[0032] All figures should be understood as guide values. Columns of similar polarity, for example from other manufacturers, are permitted. If the separation is demonstrably also achievable with an instrument having a packed column, this is also permitted.

[0033] In the handling of the samples, the moisture sensitivity thereof should be noted.

[0034] Instrument: Capillary gas chromatograph with TCD and integrator e.g. HP 5890 with HP 3396 integrator

TABLE-US-00001 Separation column: Capillary column Length: 25 m Internal 0.20 mm diameter: Film thickness: 0.33 mm Stationary HP Ultra 1 phase: Temperatures: Column oven: 120° C.-2 min-10°/ min-275° C.-8 min Injector: 250° C. Delector: 280° C. Carrier gas: helium Flow rate: about 1 ml/min Split ratio: about 1:100 Sample injected: 0.4 ml

[0035] Evaluation is effected by standardization to 100 area %.

Example 1

[0036] Dynasylan® 40 (300 g), 2-propylheptanol (1030 g) and titanium tetrabutoxide (300 μ, 0.1% by weight based on Dynasylan® 40) were initially charged and heated to 200° C. while stirring. Ethanol formed was removed from the reaction mixture by means of a distillation system. The mixture was stirred at this temperature for 24 h, then 2-propylheptanol (boiling range 205-220° C.) was distilled off at atmospheric pressure. The residual free alcohol was removed under reduced pressure (1 mbar, 200° C.). The reaction product obtained (801 g) was a pale yellowish, slightly viscous liquid. The reaction product was analyzed by means of .sup.13C NMR. The analysis demonstrates that the reaction product obtained was a 2-propylheptyl silicate.

[0037] The transesterification yield was 98%, i.e. 98% of the ethoxy groups of the ethyl silicate used were replaced by 2-propylheptyloxy groups, i.e. transesterified, in accordance with the invention.

[0038] .sup.13C-NMR (100 MHz, CDC1.sub.3): δ=65.9-66.5 (m, 1C), 39.7-40.1 (m, 1C), 32.9-33.5 (m, 1C), 32.3-32.7 (m, 1C), 30.6-31.1 (m, 1C), 26.4-26.9 (m, 1C), 22.6-23.0 (m, 1C), 19.8-20.3 (m, 1C), 14.4-14.7 (m, 1C), 14.1-14.3 (m, 1C) ppm.

[0039] European patent application 16164818.3 filed Apr. 12, 2016, is incorporated herein by reference. Numerous modifications and variations on the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.