Process for producing organoalkoxysilanes from organic acids or cyanates and haloalkylalkoxysilanes
View Patent ↗A process for the preparation of organoalkoxysilanes containing one or more organic functional groups derived from organic acids or hydrogen cyanates, by a continuous or batch process utilizing a solid guanidinium salt as a phase transfer catalyst for the reaction between a liquid phase haloalkylalkoxysilane and a solid phase alkali or alkaline earth metal salt or ammonium salt of an organic acid or a metal cyanate.
1. A process for preparing an organoalkoxysilane which comprises:
a) reacting an organic acid or hydrogen cyanate with a base to form an alkali or alkaline earth metal salt or ammonium salt of the organic acid or metal cyanate in the wet or dry state,
b) mixing the neutralized organic acid or metal cyanate in the wet or dry state with a catalytic amount of a guanidinium salt,
c) producing a solid state mixture of the neutralized organic acid or metal cyanate and the guanidinium salt; and
d) reacting the solid state mixture of the neutralized organic acid or metal cyanate and guanidinium salt with a liquid haloalkylalkoxysilane to provide organoalkoxysilane product and alkali metal halide or ammonium halide by-product.
2. The process of claim 1 , wherein the haloalkylalkoxysilane is described by the general formula:
XR 1 Si(OR 2 ) z R 3 3−z , wherein
R 1 is an alkyl, alkylene or alkylenoxyalkylene group comprising 1 to 20 carbon atoms;
R 2 is an alkyl group comprising 1 to 4 carbon atoms or an alkoxyalkyl group comprising 2 to 4 carbon atoms;
R 3 is a monovalent hydrocarbon group;
X is a halogen atom; and
z is an integer of 1, 2, or 3.
3. The process of claim 1 , wherein the organic acid is selected from the group consisting of carboxylic, dicarboxylic, phosphinic, phosphonic, sulfinic, sulfonic, sulfamic, and hydroxamic acids.
4. The process of claim 1 , wherein the guanidinium salt is a hexaalkylguanidinium salt.
5. The process of claim 4 , wherein the alkyl group of the hexaalkylguanidinium salt is an aliphatic hydrocarbon of C 1 –C 20 carbon atoms.
6. The process of claim 1 , wherein the base is an alkali or alkaline earth metal, an alkali or basic salt of the metal, a metal alcoholate, or an ammonia and the metal cation is derived from the alkali metals of group 1A and the alkaline earth metals of group 2A of the periodic table.
7. The process of claim 1 , wherein the base is an aqueous solution and neutralization reaction step (a) is conducted in an aqueous environment.
8. The process of claim 1 , wherein the guanidinium salt is an aqueous solution.
9. The process of claim 6 , wherein the metal alcoholate is metal methylate or metal ethylate.
10. The process of claim 1 , wherein the neutralized organic acid or metal cyanate and guanidinium catalyst solutions are mixed with the haloalkylalkoxysilane before alcohol removal and drying.
11. The process of claim 1 , wherein the carboxylic acid is selected from acrylic acid and methacrylic acid.
12. The process of claim 1 , wherein the haloalkyalkoxysilane is a chloroalkylalkoxysilane.
13. The process of claim 12 , wherein the chloroalkylalkoxysilane is selected from the group consisting of chloropropyltrimethoxysilane, chloropropyltriethoxysilane, chloropropylmethyldimethoxysilane, and chloropropylmethyldiethoxysilane.
14. The process of claim 1 , wherein the molar ratio of the organic acid or hydrogen cyanate to the base is between about 1.2:1 and 1:1.2 per reactive site on the base.
15. The process of claim 1 , wherein the molar ratio of the alkali or alkaline earth metal salt or ammonium salt of the organic acid or the metal cyanate to the haloalkylalkoxysilane is between about 1.2:1 and about 1:2 per reactive site on the alkali or alkaline earth metal salt or ammonium salt of the organic acid or the metal cyanate.
16. The process of claim 1 , wherein the guanidinium salt is used in an amount of about 0.001 mole to about 0.1 mole per molar equivalent of the alkali or alkaline earth metal salt or ammonium salt of the organic acid or metal cyanate.
17. The process of claim 1 , wherein the guanidinium salt is used in an amount of about 0.003 mole to about 0.03 mole per molar equivalent of the alkali or alkaline earth metal salt or ammonium salt of the organic acid or metal cyanate.
18. The process of claim 1 , wherein the alkali metal salt of the organic acid or the metal cyanate is a salt or cyanate of sodium or potassium.
19. The process of claim 1 , wherein the neutralization reaction step (a) is conducted at a temperature from about −50° C. to about 215° C. with simultaneous cooling to remove the heat of reaction, to form a solution, paste, or solid form of an alkali or alkaline earth metal salt or ammonium salt of the organic acid or metal cyanate.
20. The process of claim 1 , wherein the product reaction step (d) is conducted at a temperature from about 80° C. to about 200° C., with sufficient residence time and with simultaneous cooling to remove the heat of reaction to form the crude organoalkoxysilane product and byproduct metal or ammonium halide salt.
21. The process of claim 1 , wherein the reactions are performed in the absence of an added solvent.
22. The process of claim 1 , wherein the haloalkylalkoxysilane is additionally utilized in excess as a diluent for the formed by-product halide salt and as a wash solvent for the separated by-product halide salt.
23. The process of claim 1 , wherein a hydrocarbon solvent is utilized as a diluent for the formed by-product halide salt and/or as a wash solvent for the separated by-product halide salt.
24. The process of claim 23 , wherein the hydrocarbon solvent is selected from the group consisting of toluene, xylene, hexane, heptane, an aliphatic mixture, and mixtures thereof.
25. The process of claim 1 , wherein a hydrocarbon solvent is utilized to protect the organoalkoxysilane product during water extraction or separation of the by-product halide salt.
26. The process of claim 25 , wherein the hydrocarbon solvent is selected from the group consisting of toluene, xylene, hexane, heptane, or an aliphatic mixture.
27. The process of claim 1 , wherein polymerization is inhibited by the addition of one or more polymerization inhibitors.
28. The process of claim 27 , wherein the polymerization inhibitor is selected from the group consisting of hydroquinone, hydroquinone monomethylether, 2,6-di-t-butyl-4-methylphenol, 4,4′-methylenebis(2,6-di-t-butylphenol), phenothiazine, N,N-dialkylaminomethylene phenol,N,N′-diphenyl-p-phenylenediamine, phenyl-2-naphylamine, 2,2,6,6-tetramethyl(1-piperidinyloxy) radical, or a sulfur containing compound or combinations thereof.
29. The process of claim 28 , wherein the inhibitor is maintained active by the co-addition of oxygen.