Heteroatom-Containing Silane Compound

Abstract

The invention relates to silane compounds of the general formula (I) as defined herein containing at least one heteroatom bridged to a silicon atom via a sp.sup.2-hybridized quaternary carbon atom, a process for preparing the silane compounds, and the use of the silane compounds as end-capping agent, crosslinker, and/or adhesion promoter in curable compositions.

Claims

1. A silane compound of the general formula (I) containing at least one heteroatom bridged to a silicon atom via a sp.sup.2-hybridized quaternary carbon atom ##STR00006## wherein each R.sup.1 is independently selected from a hydrolysable group, each R.sup.4 is independently selected from hydrogen or a linear or branched, substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms which may contain at least one heteroatom; X is a divalent or polyvalent heteroatom; each R.sup.5 is independently selected from oxygen, hydrogen, or a linear or branched, substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms which may contain at least one heteroatom; R.sup.2 and R.sup.3 are same or different and, independently from one another, selected from hydrogen or a linear or branched, substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms which may contain at least one heteroatom, or R.sup.2 and R.sup.3 may form a cyclic structure; n is 1, 2 or 3, m is 1 or 2, k is 0 or 1, wherein the sum of n, m, and k is 4; and q is an integer selected from 0 to 3.

2. The silane compound according to claim 1, having the general formula (I-A) ##STR00007## wherein R.sup.1, R.sup.4, R.sup.5, X, n, m, k, and q are as defined in claim 1; R.sup.6, R.sup.7 and Ware same or different, independently from one another, selected from hydrogen, a hydroxy group, or a linear or branched, substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms which may contain at least one heteroatom.

3. The silane compound according to claim 2, wherein R.sup.6, R.sup.7 and Ware the same or different and independently from one another are selected from hydrogen, C.sub.1 to C.sub.20 alkyl, C.sub.4 to C.sub.8 cycloalkyl or C.sub.6 to C.sub.20 aryl groups which may contain at least one heteroatom.

4. The silane compound according to claim 1, wherein i) each R.sup.1 is independently selected from the group consisting of alkoxy, carboxy, oxime, amino, amido, lactato, alkenoxy, and acetoxy groups; and/or ii) each R.sup.4 is independently selected from hydrogen, or C.sub.1 to C.sub.20 alkyl, C.sub.2 to C.sub.20 alkenyl, C.sub.5 to C.sub.20 aryl, C.sub.7 to C.sub.20 alkaryl, or C.sub.7 to C.sub.20 aralkyl groups which may contain at least one heteroatom selected from O, N, S, P, Si, Cl, Br, I or F.

5. The silane compound according to claim 1, wherein each R.sup.4 is independently selected from hydrogen, C.sub.2 to C.sub.12 alkyl, C.sub.2 to C.sub.12 alkenyl, or C.sub.5 to C.sub.12 aryl group, any of which may contain at least one heteroatom.

6. The silane compound according to claim 1, wherein each R.sup.4 is independently selected from hydrogen, ethyl, n-propyl, isopropyl, trifluoropropyl, aminopropyl, n-butyl, sec-butyl, tert-butyl, vinyl, phenyl, or pyridinyl group.

7. The silane compound according to claim 1, wherein X is selected from O, S, N or P.

8. The silane compound according to claim 1, wherein n is 2 or 3 and/or m is 1.

9. A curable composition comprising the silane compound according to claim 1.

10. An end-capping agent, crosslinker and/or adhesion promoter comprising the silane compound according to claim 1.

11. A process for preparing a silane compound of the general formula (I) as defined in claim 1, comprising the steps of: a) contacting at least one metal with an organic solvent, wherein the metal is selected from the group consisting of Mg, Na, Li, Ca, Ba, Cd, and Zn or mixtures or alloys thereof, b) adding at least one silane of the general formula (II) to the organic solvent
si(R.sup.1).sub.n+1(R.sup.4)k  (II),  wherein R.sup.1 and R.sup.4, n, and k are as defined above, and c) adding at least one halogenated compound of the general formula (III) to the reaction medium obtained in the step b) ##STR00008##  wherein R.sup.2, R.sup.3, and R.sup.5, and q are as defined above; and  Y is a halogen atom.

12. The process according to claim 11, wherein the halogenated compound has the general formula (III-A) ##STR00009## wherein wherein R.sup.5 to R.sup.8, X, and q are as defined above; and Y is a halogen atom.

13. The process according to claim 11, wherein the halogenated compound of the general formula (III) or (III-A) is added in step c) while maintaining the temperature at a temperature lower than or equal to the boiling point of the organic solvent.

14. The process according to claim 11, wherein the organic solvent is selected from cyclic ether, dialkyl ether, or aryl ether.

15. The process according to claim 11, wherein the organic solvent is selected from dioxane, tetrahydrofuran, 2-methyl-tetrahydrofuran, diethyl ether or cyclopentyl methyl ether.

16. The process according to claim 11, wherein the organic solvent is tetrahydrofuran and the halogenated compound of the general formula (III) or (III-A) is added in step c) while maintaining the temperature at a temperature between 40° C. and 66° C.

17. The process according to claim 11, further comprising step d): removing the organic solvent after the reaction in the step c) and adding a second organic solvent which is different from the removed solvent.

18. The process according to claim 17, wherein the second organic solvent is selected from C.sub.4-20 hydrocarbons with a dielectric constant at 20° C. lower than 3.

19. The process according to claim 17, wherein the second organic solvent is selected from n-pentane, n-hexane, n-heptane, cyclohexane, benzene, toluene or xylene.

20. A moisture curable composition comprising the silane compound prepared by the process of claim 11.

Description

EXAMPLES

Preparation of the Silane Compound According to the Invention

Examples 1 to 4

[0063] ##STR00005##

[0064] A three-neck round-bottom flask equipped with cooling condenser, dropping funnel, magnetic stir bar and a stopper is charged with magnesium chips (150 mmol, 1.5 eq, 3.6465 g) and flame-dried under reduced pressure. A crystal of iodine is added and sublimed by heating, etching the surface of the magnesium. Tetrahydrofuran (150 ml), followed by a silane of the general formula (II), wherein R.sup.1 and R.sup.4 are as defined in Table 1, is added to the flask (150 mmol, 1.5 eq). The stopper is swapped for a thermometer. To the dropping funnel 2-bromothiophene (100 mmol, 1 eq) is added. While stirring, 10 vol % 2-bromothiophene is added to the flask in one portion. An increase in temperature is observed. Dropping is continued while maintaining a temperature between 40° C. and 50° C. After the addition heating to 60° C. is turned on for 2 h. The tetrahydrofuran is distilled off, leaving a wet grey solid. Hexane (150 ml) is added to the flask and the solid is suspended, turning the color from grey to white. The solids are filtered, and hexane is distilled off yielding a crude product (yield provided in Table 1). Clean product is obtained by the means of vacuum distillation at 1.0×10.sup.−3 mbar. The obtained silane compound has the above-shown general formula, wherein R.sup.1 and R are as defined in Table 1.

TABLE-US-00001 TABLE 1 Yield of silane compounds synthesis Crude Yield Distillation temperature Compound R R.sup.1 [%] at 1.0 × 10.sup.−3 mbar [° C.] Ex. 1 methoxy methoxy 51 85 Ex. 2 methyl methoxy 63 92 Ex. 3 phenyl methoxy 56 138 Ex. 4 vinyl methoxy 58 112

Example 5

[0065] A silane compound was prepared according to the process for the preparation of Example 2 except that 2-bromothiphene was first added to the tetrahydrofuran and then the methyltrimethoxysilane was added thereto. The yield of synthesized silane compound according to Example 5 was 37%.

Examples 6 and 7

[0066] Silane compounds were prepared according to the process for the preparation of Example 2 except that 2-bromothiphene was added while maintaining a temperature as shown in Table 2. The yields of synthesized silane compounds according to Examples 6 and 7 are provided in Table 2.

TABLE-US-00002 TABLE 2 Reaction temperature Compound [° C.] in step c) Crude yield [%] Ex. 2 40-50 63 Ex. 6 50-60 60 Ex. 7 60-66 55