3-(Vinylbenzyloxy)propylsilane compounds and their preparation

Abstract: 3-(vinylbenzyloxy)propyl silanes are of the general formula: CH₂CH-benzylidene-CH₂OCH₂CH₂CH₂SiR¹ n (OR²) 3-n wherein R¹ and R² each are a C1-4 hydrocarbon residue, e.g., alkyl, and n is 0.1 or 2. Synthesis is from the corresponding 3-(vinylbenzyloxy)-1-propene, by reaction in the presence of a platinum catalyst with either a) a hydrogen silane HSi R¹ n (OR²) 3-n , or b) a hydrogen silane HSiR¹ n X 3-n , when the product is reacted with an alcohol of a C1-4 hydrocarbon residue and optionally with urea. The novel silanes can be copolymerized with a monomer selected from styrenes, acrylates, methacrylates, vinyl esters, ethylene, propylene, vinyl chloride, butadiene, isoprene, chloroprene and α-olefins, or the silane is used directly to treat organic or inorganic material.

Description: The present invention relates to novel silane compounds and, more particularly, to compounds having a styrene skeleton which are highly homo- and copolymerizable, so that they are useful as a silane coupling agent or as polymerizing monomers. Hitherto known alkoxysilane compounds of the type which contain a styrene skeleton include vinylbenzyltrimethoxysilane (Masanori Kokubo et al., Kohbunshi Ronbunshu , volume 36, page 201 (1981) and vinyl phenyltrimethoxysilane (Y. Kawakami et al., Polymer Journal , volume 17, page 1159 (1985)). In the syntheses thereof, however, it is necessary to use styrene-type Grignard reagents which are quite unstable and liable to polymerize (namely, vinylbenzylmagnesium halide in the former compound, and vinylphenylmagnesium halide in the latter compound). Therefore, the syntheses of such compounds on an industrial scale are very difficult. In addition, since the syntheses of the foregoing compounds require a large quantity of solvent and a process of removing salts through filtration, they are at a disadvantage in entailing high cost of manufacturing. As for another styrene skeleton-containing alkoxysilane, vinylphenetyltrimethoxysilane is known to be obtained by hydrosilylation of divinylbenzene with a hydrogensilane (G. Greert, Makromol. Chem ., volume 53, page 19 (1962)). In general, the hydrosilylation method is said to be suitable for syntheses of functional group-containing alkoxysilanes as disclosed in FR-A-2 162 114 as regards low cost and good working efficiency, because it does not use any solvent and does not require any filtration process. In case of the above-cited compound, however, divinylbenzene used as a starting material is extremely unstable and apt to polymerize and, what is worse, it has a disadvantage in that there is a tendency for addition of two silane molecules upon hydrosilylation because of the presence of two vinyl groups almost equivalent in reactivity in the substrate, whereby the yield of the intended compound is lowered. Therefore, objects of the present invention are to provide novel styrene skeleton-containing alkoxysilane compounds which are useful as a silane coupling agent or as polymerizing monomers, and to provide methods of producing such compounds. We have now found that the hydrosilylation can be effected with ease by the use of 3-(vinylbenzyloxy)-1-propenes as a starting material, and can provide styrene skeleton-containing alkoxysilane compounds at a lower price, and that the compounds obtained thereby are novel compounds. According to the present invention we provide 3-(vinylbenzyloxy)propylsilane compounds represented by the following general formula (1). CH 2 CH-Ø-CH 2 OCH 2 CH 2 CH 2 SiR 1 (OR 2 ) 3-n wherein Ø represents a benzene ring; R 1 and R 2 are each a hydrocarbon residue containing 1 to 4 carbon atoms and n is 0, 1 or 2. Specific examples of R 1 and R 2 are a methyl ethyl, propyl, isopropyl and butyl group, of which methyl and ethyl are most preferred. In preferred compounds n is 0 and R 2 methyl or ethyl, or n is 1 and R 1 is methyl and R 2 methyl or ethyl. The 3-(vinylbenzyloxy)propylsilane compounds of the present invention are styrene skeleton-containing alkoxysilane compounds which can be easily synthesized by a hydroxilylation reaction of 3-(vinylbenzyloxy)-1-propenes, which are easy to prepare and stable, with hydrogensilanes in the absence of a solvent without producing by-products including a salt. The compounds of the present invention can thus be easily manufactured using as a starting compound a 3-(vinylbenzyloxy)-1-propene represented by the following formula (2): CH 2 CH-Ø-CH 2 OCH 2 CH=CH 2 The 3-(vinylbenzyloxy)-1-propenes represented by the above formula (2) can be synthesized with ease using a known method (G.F. Dalelio et al., Journal of Polymer Science , volume 5, page 1245 (1867)). In these compounds, it is feasible to selectively hydrosilylate only the intended double bond in the allyloxy group since the double bond in the allyloxy group is more susceptible to hydrosilylation than the vinyl group in the styrene skeleton. More specifically, the compounds repesented by the general formula (2) include 3-(2-vinylbenzyloxy)-1-propene, 3-(3-vinylbenzyloxy)-1-propene and 3-(4-vinylbenzyloxy)-1-propene. The 3-(vinylbenzyloxy)propylsilane compounds of the present invention can be synthesized by means of either of the two methods described below. The symbols R 1 , R 2 and n used in the following formulae have the same meanings as those described for the foregoing general formula (1), respectively. In a first synthesis method, the 3-(vinylbenzyloxy)propylsilane compounds of the present invention are obtained by allowing the 3-(vinylbenzyloxy)-1-propene compounds represented by the formula (2) to undergo a hydrosilylation reaction with hydrogensilanes represented by the general formula (3) in the presence of a platinum catalyst: HSiR 1 n (OR 2 ) 3-n Examples of a compound represented by the foregoing general formula (3) include alkoxysilane compounds such as trimethoxysilane, methyldiethoxysilane, ethyldiethoxysilane and dimethylbutoxysilane. In a second synthesis method, 3-(vinylbenzyloxy)propylhalogenosilane compounds represented by the general formula, CH 2 CH-Ø-CH 2 OCH 2 CH 2 CH 2 SiR 1 n X 3-n , are firstly prepared by allowing a 3-(vinylbenzyloxy)-1-propene compound to undergo a hydrosilylation reaction with a hydrogen silane represented by the general formula (4) in the presence of a platinum catalyst: HSiR 1 n X 3-n wherein X represents a halogen atom. As for the compounds represented by the foregoing formula (4), chlorosilane compounds such as trichlorosilane, methyldichlorosilane, ethyldichlorosilane and dimethylchlorosilane can be given as examples. Then, the compound obtained is made to react with an alcohol represented by the general formula (5) to yield the 3-(vinylbenzyloxy)propylsilane compounds of the present invention. R 2 OH As for the alcohols represented by the foregoing general formula (5), methanol, ethanol, propanol, isopropanol and butanol can be given as examples. Specifically, the 3-(vinylbenzyloxy)propylsilane compounds of the present invention include 3-(4-vinylbenzyloxy)propyltrimethoxysilane, 3-(4-vinylbenzyloxy)propylmethyldimethoxysilane, 3-(4-vinylbenzyloxy)propylmethyldiethoxysilane, 3-(3-vinylbenzyloxy)propylethyldimethoxysilane and 3-(2-vinylbenzyloxy)propyldimethylbutoxysilane. In both first and second synthesis methods, it is desirable that a reactor equippment with a stirrer, a thermometer, a reflux condenser and a dropping funnel should be used. The amount of the platinum catalyst used is 5 to 500 ppm to the 3-(vinylbenzyloxy)-1-propene compound used, and the hydrogensilanes represented by the general formulae (3) and (4) are each dropped in an amount of 1-1.5 equivalents to the 3-(vinylbenzyloxy)-1-propene compound used. It is to be desired that these reactions should be carried out at 50-150°C. It is to be specially noted that the reaction of a 3-(vinylbenzyloxy)propylhalogenosilane compound with an alcohol, which is part of the second synthesis method, can be effected without using any solvent, provided that 1.1-2 equivalents of an alcohol is used together with 1-1.5 equivalents (to the halogen atom) of urea. Additionally, the urea hydrochloride-alcohol phase can be removed by using a liquid separation procedure. The 3-(vinylbenzyloxy)propylsilane compounds of the present invention are of industrially great usefulness as a silane coupling agent for bringing about an improvement in characteristics of composite materials, or as polymerizing monomers. When a compound of the present invention is used as a silane coupling agent, it can suitably perform a function as a treatment agent or additive for inorganic materials such as glass fibers, clay, silica, quartz powder, mica or alumina, and for organic materials such as polyethylene, polypropylene, polystyrene, unsaturated polyester, natural rubber or synthetic rubber. Therein, they can widely exert their effect so as to improve the characteristics of composite materials, including enhancement of mechanical strength and adhesiveness, stabilization of electric characteristics, reforming of their resinous component and surface modification, or fully achieve their effect as a primer for heightening adhesion power of sealing agents. On the other hand, when a compound of the present invention is used as a polymerizing monomer, it can undergo radical copolymerization with various kinds of radical polymerizing monomers, e.g., styrenes, acrylates, methacrylates, vinyl esters, ethylene, propylene, vinyl chloride, butadiene, isoprene, chloroprene or alpha-olefins in the presence of a polymerization initiator such as an organic peroxide, or an azo compound to produce polymers containing hydrolyzable alkoxysilyl groups in the side chains. These polymers have not only the property of being cross-linked efficiently with water under mild reaction conditions, but also great adhesiveness to various kinds of substrates because they contain alkoxy groups excellent in affinity for inorganic and metallic materials. In addition, their physical properties, including heat resistance, weather resistance, gas perviousness and shock resistance are highly satisfactory. Therefore, they can also be used in high functional plastic materials and functional film materials. The present invention is illustrated in greater detail by reference to the following examples. EXAMPLE 1 After 691.0 g (5.0 mole) of a 50% 2-propenyl alcohol solution of sodium 2-propenoxide, 16.0 g of tetrabutylammonium bromide and 1.0 g of BHT were placed and mixed in a 3-liter glass flask equipped with a stirrer, a reflux condenser, a thermometer and a dropping funnel, 763.0 g (5.0 mole) of 4-vinylbenzyl chloride was added dropwise to the mixture from the dropping funnel as the temperature was kept at 35-40°C to make them undergo reaction. At the conclusion of the reaction, water was added to dissolve the produced salt. The resulting organic phase was separated, and then distilled to collect a 83-84°C/2 mmHg fraction. Thus, 795.4 g of 3-(4-vinylbenzyloxy)-1-propene was obtained in a 91.3% yield. Subsequently, a 174.2 g (1.0 mole) portion of the thus obtained 3-(4-vinylbenzyloxy)-1-propene, 0.2 g of a 4% isopropyl alcohol solution of H 2 PtCl 6 and 0.5 g of BHT were placed in a 500-ml glass flask equipped with a stirrer, a reflux condenser, a thermometer and a dropping funnel. Thereto, 122.2 g (1.0 mole) of trimethoxysilane was added dropwise from the dropping funnel over a 2-hour period as the reaction mixture was kept at 70-80°C. Then, the resulting solution was ripened for 30 minutes at 80°C. The thus obtained solution was distilled to yield 265.8 g of the intended compound having a boiling point of 143-147°C/2 mmHg. The yield thereof was 88.0%. The results of mass spectrum (MS), nuclear magnetic resonance spectrum (NMR) and infrared absorption spectrum measurements of this compound are shown below. Nuclear Magnetic Resonance Spectrum (NMR) a: 3.43 ppm (S), b: 0.45-0.73 ppm (M), c: 1.30-1.88 ppm (M), d: 3.31 ppm (T), e: 4.34 ppm (S), f: 7.05-7.35 ppm (M), g: 6.56 ppm (M), h: 5.09 ppm (M), i: 5.55 ppm (M). Herein, S and M in parentheses symbolize Singlet and Multiplet, respectively. This result is in good accordance with the theoretical spectrum of the compound having the following structural formula; Mass Spectrum (MS) : m/z (relative intensity of spectral line, assignment) 296 (8, M + ), 264 (52, M-CH 3 OH), 147 (15), 121 (100, Si(OCH 3 ) 3 ), 117 (71), 91 (49). This result is in good accordance with the theorectical spectrum of the above-illustrated compound. Infrared Absorption Spectrum (IR ): (cm -1 ) 2949, 2830, 1630, 1515, 1460, 1410, 1360, 1200, 1090, 990, 910. This result is also in good accordance with the predictable spectrum of the foregoing compound. Thus, the obtained substance is confirmed to be the compound represented by the following formula: EXAMPLE 2 In the same manner as in Example 1, except that 134.3 g (1.0 mole) of methyldiethoxysilane was used in the place of 122.2 g (1.0 mole) of trimethoxysilane, 256.4 g of a compound having a boiling point of 148-151°C/2 mmHg was obtained in a 83.1 % yield. The results of mass spectrum (MS), nuclear magnetic resonance spectrum (NMR) and infrared absorption spectrum measurements of this compound are shown below. Nuclear Magnetic Resonance Spectrum (NMR) a: 1.09 ppm (T), b: 3.59 ppm (Q), c: -0.03 ppm (S), d: 0.38-0.63 ppm (M), e: 1.30-1.78 ppm (M), f: 3.25 ppm (T), g: 4.29 ppm (S), h: 6.97-7.25 ppm (M), i: 6.52 ppm (M), j: 5.02 ppm (M), k: 5.50 ppm (M). Herein, S, M, T and Q in parentheses symbolize Singlet, Multiplet, Triplet, and Quartet, respectively. This result is in good accordance with the theoretical spectrum of the compound having the following structural formula; Mass Spectrum (MS) : m/z (relative intensity of spectral line, assignment) 308 (1, M + ), 262 (79, M-CH 3 CH 2 OH), 145 (10), 133 (63, SiMe(OCH 2 CH 3 ) 2 ), 117 (100), 105 (15), 89 (14). This result is in good accordance with the theoretical spectrum of the above-illustrated compound. Infrared Absorption Spectrum (IR ): (cm -1 ) 2970, 2940, 2870, 1630, 1520, 1450, 1400, 1360, 1260, 1170, 1110, 1080, 995, 950. This result is also in good accordance with the predictable spectrum of the foregoing compound. Thus, the obtained substance is confirmed to be the compound represented by the following formula: EXAMPLE 3 87.1 g (0.5 mole) of 3-(4-vinylbenzyloxy)-1-propene, 0.1 g of a 4 % isopropyl alcohol solution of H 2 PtCl 6 and 0.5 g of BHT were placed in a 500-ml glass flask equipped with a stirrer, a reflux condenser, a thermometer and a dropping funnel. Thereto, 57.5 g (0.5 mole) of methyldichlorosilane was added dropwise from the dropping funnel over a 2-hour period as the reaction mixture was kept at 70-80 °C. Then, the resulting solution was ripened for 30 minutes at 80°C . To the resulting solution, 66.1 g (1.1 moles) of urea was added, and 48.1 g (1.5 moles) of methanol was further added dropwise under room temperature. Thereupon, the urea hydrochloride-methanol phase was separated to form the lower layer. The lower layer was removed, while the upper layer was distilled to give 121.0 g of a compound having a boiling point of 147-151°C/2 mmHg. This compound was identified as the compound prepared in Example 2 by the measurements of mass spectrum (MS), nuclear magnetic resonance spectrum (NMR) and infrared absorption spectrum thereof. The yield in this preparation process was 78.4 %.

Claims: 3-(vinylbenzyloxy)propylsilane compounds represented by the general formula CH 2 CH-Ø-CH 2 OCH 2 CH 2 CH 2 SiR 1 n (OR 2 ) 3-n , wherein Ø represents benzylidene, R 1 and R 2 each represent a hydrocarbon residue containing 1 to 4 carbon atoms, and n represents 0 or the integer 1 or 2. A compound as claimed in Claim 1, wherein n is 0 and R 2 is a methyl or ethyl group. A compound as claimed in Claim 1, wherein n is 1, R 1 is a methyl group and R 2 is a methyl or ethyl group. A method of synthesizing a 3-(vinylbenzyloxy)-propylsilane compound as claimed in Claim 1, 2 or 3, which comprises causing a 3-(vinylbenzyloxy)-1-propene compound represented by the general formula CH 2 CH-Ø-CH 2 OCH 2 CHCH 2 and a hydrogen silane represented by the general formula HSiR 1 n (OR 2 ) 3-n , to undergo a hydroxilylation reaction in the presence of a platinum catalyst; the symbols in the formulae being defined as in Claim 1 A method as claimed in Claim 4, wherein said hydrogensilanes include at least one alkoxysilane. A method as claimed in Claim 5, wherein said alkoxysilane is at least one hydrogen silane selected from trimethoxy hydrogensilane, methyldiethoxy hydrogen silane, ethyldiethoxy hydrogen silane and dimethyl butoxy hydrogen silane. A method of synthesizing a 3-(vinylbenzyloxy)-propylsilane compound as claimed in Claim 1, 2 or 3, which comprises preparing a 3-(vinylbenzyloxy)propylhalogenosilane compound represented by the general formula CH 2 CH-Ø-CH 2 OCH 2 CH 2 CH 2 SiR 1 n X 3-n wherein X represents a halogen atom and the other symbols are as defined in Claim 1, 2 or 3, by causing a 3-(vinylbenzyloxy)-1-propene compound as defined in Claim 4 to undergo a hydrosilylation reaction with a hydrogen silane represented by the general formula HSiR 1 n X 3-n , in the presence of a platinum catalyst; and reacting the resultant 3-(vinylbenzyloxy)propylhalogenosilane with an alcohol represented by the general formula R 2 OH, wherein R 2 represents a hydrocarbon residue containing 1 to 4 carbon atoms. A method as claimed in Claim 7, wherein said halogen atom represented by X is a chlorine atom. A method as claimed in Claim 7 or 8, wherein said hydrogensilane includes at least one chlorosilane compound selected from trichlorosilane, methyldichlorosilane, ethyldichlororsilane and dimethylchlorosilane. A method as claimed in Claim 7, 8 or 9, wherein said reaction of the 3-(vinylbenzyloxy)propylhalogenosilane compound with an alcohol is carried out by using 1 to 1.5 equivalents (to the halogen atom) of urea together with the alcohol and controlling the amount of the alcohols to 1.1 to 2 equivalents (to the halogen atom) so as to effect the reaction without using any other solvent. A method as claimed in any of Claims 4 to 10, wherein said 3-(vinylbenzyloxy)-1-propene compound is selected from 3-(2-vinylbenzyloxy)-1-propene, 3-(3-vinylbenzyloxy)-1-propene and 3-(4-vinylbenzyloxy)-1-propene. A method as claimed in any of Claims 4 to 11, wherein the amount of hydrogen silane used is 1 to 1.5 equivalents per equivalent of the 3-(vinylbenzyloxy)-1-propene compound. A method as claimed in any of Claims 4 to 12, wherein the amount of platinum catalyst used is 5-500 ppm of the 3-(vinylbenzyloxy)-1-propene compound.

Inventors: ENDO MIKIO, ISHIHARA TOSHINOBU, KUBOTA TOHRU, UEHARA KATSUHIRO, ENDO, MIKIO, ISHIHARA, TOSHINOBU, KUBOTA, TOHRU, UEHARA, KATSUHIRO
Applicants: SHINETSU CHEMICAL CO, SHIN-ETSU CHEMICAL CO., LTD.
Application year: 1991
Main classification: C07F7
IPC codes: C07F7, C08F30