Thexyl trialkoxy silanes; method for their preparation; and uses thereof

Abstract: Several novel thexyl trialkoxy silanes can be synthesized by a dehydrochlorination condensation reaction between thexyl trichlorosilane and an alcohol, e.g., methyl, ethyl, isopropyl and isobutyl alcohols, the novel compounds being characterized by analytical data. The compounds are useful as intermediates in the synthetic preparation of other organosilicon compounds, starting materials for various silicones, surface-treatment agents for inorganic materials and additives in complex catalysts.

Description: The present invention relates to novel organosilicon compounds. More particularly, the invention relates to novel organosilane compounds having a thexyl group bonded to the silicon atom not known in the prior art nor described in any literature. The novel organosilicon compounds provided by the invention are thexyl trialkoxy silanes represented by the general formula H-CMe₂-CMe₂-Si(OR)₃, (I) in which Me is a methyl group and R is an alkyl group. In the drawings: Figures 1, 2, 3 and 4 are each an infrared absorption spectrum of thexyl trimethoxy silane, thexyl triethoxy silane, thexyl triisopropoxy silane and thexyl triisobutoxy silane, respectively, prepared in the examples. Several organosilicon compounds having a thexyl group, i.e. 1,1,2-trimethylpropyl group, bonded to the silicon atom are known including thexyl trichlorosilane reported in Journal of American Chemical Society, volume 70, page 484 (1948) and Chem. Listy, volume 52, page 640 (1958) and thexyl dimethyl chlorosilane reported in Tetrahedron Letters, volume 26, page 5511 and page 5515 (1985). By virtue of the relatively bulky thexyl group bonded to the silicon atom of the silane compound, these thexyl silane compounds are expected to be useful compounds in the manufacture of organosilicon compounds or so-called silicones, for example, as intermediates in the preparation of silicone resins, dispersion aids for the finely divided silica filler used in the preparation of silicone rubber compositions and a surface-treatment agents for various kinds of inorganic materials as well as additives in the preparation of complex catalysts. The above mentioned chlorosilanes having a thexyl group in the molecule, however, are not very advantageous for use in actual applications because the silicon-bonded chlorine atoms readily produce the very corrosive hydrogen chloride when the compounds are reacted with a compound or substrate having an active hydrogen atom in the molecule, such as water. In particular, hydrogen chloride is a very notorious pollutant of the environment so that use of a thexyl-containing chlorosilane is severely limited as a starting material for silicones, surface-treatment agents for inorganic materials, additives in complex catalysts and the like. In view of the above described situation it is desirable to obtain thexyl-containing organosilane compounds which are free from the above described problems and disadvantages. Thexyl trialkoxy silanes, i.e. 1,1,2-trimethylpropyl trialkoxy silanes, have now been discovered which are compounds represented by the general formula H-CMe₂-CMe₂-Si(OR)₃, (I) in which Me is a methyl group and R is an alkyl group. The alkyl group denoted by R has, for example, 1 to 8 carbon atoms and is exemplified by methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, n-hexyl and n-octyl groups. Such thexyl trialkoxy silanes can be prepared by the reaction of thexyl trichlorosilane, which is a known compound, expressed by the structural formula H-CMe₂-CMe₂-SiCl₃, in which Me is a methyl group, and an alcohol represented by the general formula ROH, in which R has the same meaning as defined above and may for example be methyl, ethyl, isopropyl or isobutyl, e.g. by heating a mixture thereof undiluted or diluted with a suitable organic solvent such as hydrocarbon solvents, ether solvents and the like in the presence of a hydrogen chloride acceptor at a temperature in the range from 20 to 150 °C or, preferably, from 30 to 100 °C for 0.5 to 30 hours under agitation. A convenient way to conduct the reaction is under reflux of the alcohol used as the reactant in the reaction mixture. In conducting the above described reaction, the amount of the alcohol should be in the range from 3 to 4 moles per mole of thexyl trichlorosilane. When the reaction mixture is diluted with an organic solvent, the solvent is preferably a hydrocarbon solvent, e.g., benzene, toluene, xylene, n-hexane, cyclohexane and methyl cyclohexane, or an ether solvent, e.g., diethyl ether, dibutyl ether, tetrahydrofuran or dioxane, although it is also possible that the alcohol used as one of the reactants can be used in an excessive amount so as to serve also as a solvent. The hydrogen chloride acceptor can be any of the known ones including tertiary amines such as triethyl amine, tripropgl amine, tributyl amine and DBU, i.e. 1,5-diazabicyclo[5.4.0]undec-5-ene, and urea. The use of urea as a hydrogen chloride acceptor is sometimes advantageous because urea hydrochloride is formed in the reaction mixture in a separate liquid phase so that it can be readily separated by the technigue of liquid-phase separation without undertaking the rather laborious procedure of filtration. The amount of the hydrogen chloride acceptor is from 3 to 4 moles per mole of thexyl trichlorosilane. In the following, examples are given to illustrate the procedure of synthetic preparation and characterization of several thexyl trialkoxy silanes. Example 1. Into a four-necked flask of 200 ml capacity equipped with a stirrer, reflux condenser, dropping funnel and thermometer were introduced 10.6 g (0.33 mole) of methyl alcohol and 19.8 g (0.33 mole) of urea to form a mixture, into which 20.0 g (0.091 mole) of thexyl trichlorosilane were added dropwise through the dropping funnel taking 30 minutes under agitation of the reaction mixture. Since no particular cooling means was undertaken, the temperature of the reaction mixture varied from 20 to 50 °C during the dropwise addition of the silane. After completion of the dropwise addition of thexyl trichlorosilane, the temperature of the reaction mixture in the flask was increased to 70 to 80 °C and agitation was continued for an additional 6 hours at this temperature to complete the reaction. Thereafter, the reaction mixture was kept standing so that phase separation took place into layers, of which the lower layer was discarded. The liquid in the upper layer was taken and subjected to distillation under reduced pressure to give 13.3 g of a fraction boiling at 84 °C under a pressure of 27 mmHg. This product could be identified as thexyl trimethoxy silane from the analytical results shown below so that the above mentioned yield of the product corresponded to 0.065 mole or 71% of the theoretical yield. Mass spectrum m/z: 206 (M⁺); 121 (M⁺ - Me₂CHCMe₂) Nuclear magnetic resonance spectrum ¹H-NMR (CCl₄, 60 MHz), δ (ppm) 3.60 (s, 9H); 1.8-1.3 (m, 1H); 0.95 (s, 6H); 0.93 (d, 6H, J=6Hz) Infrared absorption spectrum See Figure 1. Example 2. The synthetic procedure was substantially the same as in Example 1 excepting replacement of the methyl alcohol with the same molar amount, i.e. 15.2 g (0.33 mole), of ethyl alcohol. Distillation of the upper layer obtained by the phase separation of the reaction mixture gave 20.1 g of a fraction boiling at 67 °C under a pressure of 3 mmHg. This product could be identified as thexyl triethoxy silane from the analytical results shown below so that the above mentioned yield of the product corresponded to 0.081 mole or 89% of the theoretical yield. Mass spectrum m/z: 248 (M⁺); 203 (M⁺ - EtO); 163 (M⁺ - Me₂CHCMe₂) Nuclear magnetic resonance spectrum ¹H-NMR (CCl₄, 60 MHz), δ (ppm) 3.81 (q, 6H, J=7Hz); 1.8-1.4 (m, 1H); 1.18 (t, 9H, J=7Hz); 0.88 (s, 6H); 0.86 (d, 6H, J=6Hz) Infrared absorption spectrum See figure 2. Example 3. The synthetic procedure was substantially the same as in Example 1 excepting replacement of the methyl alcohol with the same molar amount, i.e. 19.8 g (0.33 mole), of isopropyl alcohol. Distillation of the upper layer obtained by the phase separation of the reaction mixture gave 22.9 g of a fraction boiling at 73 °C under a pressure of 3 mmHg. This product could be identified as thexyl triisopropoxy silane from the analytical results shown below so that the above mentioned yield of the product corresponded to 0.079 mole or 87% of the theoretical yield. Mass spectrum m/z: 275 (M⁺ - Me); 231 (M⁺ - PrO); 205 (M⁺ - Me₂CHCMe₂) Nuclear magnetic resonance spectrum ¹H-NMR (CCl₄, 60 MHz), δ (ppm) 4.21 (h, 3H, J=6Hz); 1.9-1.4 (m, 1H); 1.19 (d, 18H, J=6Hz); 0.90 (d, 6H, J=6Hz) Infrared absorption spectrum See Figure 3. Example 4. The synthetic procedure was substantially the same as in Example 1 excepting replacement of the methyl alcohol with the same molar amount, i.e. 24.4 g (0.33 mole), of isobutyl alcohol. Distillation of the upper layer obtained by the phase separation of the reaction mixture gave 22.9 g of a fraction boiling at 102-103 °C under a pressure of 3 mmHg. This product could be identified as thexyl triisobutoxy silane from the analytical results shown below so that the above mentioned yield of the product corresponded to 0.069 mole or 76% of the theoretical yield. Mass spectrum m/z: 259 (M⁺- BuO); 247 (M⁺ - Me₂CHCMe₂) Nuclear magnetic resonance spectrum ¹H-NMR (CCl₄, 60 MHz), δ (ppm) 3.62 (d, 6H, J=6Hz); 2.1-1.4 (m, 4H); 1.01 (d, 24H, J=6Hz); 1.00 (s, 6H) Infrared absorption spectrum See Figure 4.

Claims: A thexyl trialkoxy silane represented by the general formula H-CMe₂-CMe₂-Si(OR)₃, in which Me is a methyl group and R is an alkyl group. A thexyl trialkoxy silane as claimed in claim 1 in which the alkyl group denoted by R has 1 to 8 carbon atoms A thexyl trialkoxy silane as claimed in claim 2 in which the group denoted by R is a methyl group. A thexyl trialkoxy silane as claimed in claim 2 in which the group denoted by R is an ethyl group. A thexyl trialkoxy silane as claimed in claim 2 in which the group denoted by R is an isopropyl group. A thexyl trialkoxy silane as claimed in claim 2 in which the group denoted by R is an isobutyl group. A method of preparing a thexyl trialkoxy silane as claimed in claim 1 which method comprises reacting a thexyl trichlorosilane having the structural formula H-CMe₂-CMe₂-SiCl₃ in which Me is a methyl group, with an alcohol represented by the general formula ROH in which R is an alkyl group, in the presence of a hydrogen chloride acceptor. A method as claimed in claim 7 wherein urea is the hydrogen chloride acceptor. Use of a thexyl trialkoxy silane as claimed in claim 1 as an intermediate in the preparation of organosilicon compounds, as a dispersion aid, as a surface-treatment agent, or as an additive in the preparation of complex catalysts.

Inventors: IWABUCHI MOTOAKI, KUDO MUNEO, SHINOHARA TOSHIO, IWABUCHI, MOTOAKI, KUDO, MUNEO, SHINOHARA, TOSHIO
Applicants: SHINETSU CHEMICAL CO, SHIN-ETSU CHEMICAL CO., LTD.
Application year: 1991
Main classification: C07F7
IPC codes: C07F7