Preparation of fluorosilicon compounds

Abstract

Methods of synthesizing fluorosilanes containing cyano-substituted alkyl groups are provided. For example, 3-cyano-propyldimethylfluorosilane may be produced by reacting tetramethyldisiloxane and boron trifluoride to obtain fluorodimethylsilane and then reacting the fluorodimethylsilane with allyl cyanide, in the presence of a hydrosilylation catalyst

1 . A method of making 3-cyanopropyldimethylfluorosilane, comprising:
 a) reacting tetramethyldisiloxane and boron trifluoride to obtain fluorodimethylsilane; and   b) reacting fluorodimethylsilane obtained in step a) with allyl cyanide.   
     
     
         2 . The method of  claim 1 , wherein step b) is carried out in the presence of a hydrosilylation catalyst. 
     
     
         3 . The method of  claim 1 , wherein fluorodimethylsilane and allyl cyanide are reacted in a molar ratio of from about 0.7:1 to about 1.3:1. 
     
     
         4 . The method of  claim 1 , wherein step b) is carried out in the presence of Karstedt's catalyst 
     
     
         5 . The method of  claim 1 , wherein the fluorodimethylsilane and the allyl cyanide are reacted in the presence of a hydrosilylation catalyst at a temperature of from about 70° C. to about 120° C. 
     
     
         6 . The method of  claim 1 , wherein step b) is carried out in an inert solvent capable of tbrming an azeotrope with water. 
     
     
         7 . The method of  claim 6 , wherein the inert solvent is toluene. 
     
     
         8 . The method of  claim 6 , wherein a reaction product containing 3-cyanopropyldimethylfluorosilane, inert solvent and water is obtained in step b) and the reaction product is subjected to distillation wherein water is removed by azeotropic distillation. 
     
     
         9 . The method of  claim 1 , wherein the boron trifluoride is in the form of an etherate complex. 
     
     
         10 . A method of making 3-cyanopropyldimethylfluorosilane comprising a step of reacting bis(3-cyanopropyl)tetrarnethyldisiloxane and boron trifluoride. 
     
     
         11 . The method of  claim 10 , wherein the boron trifluoride is in the form of an etherate complex. 
     
     
         12 . The method of  claim 10 , wherein the boron trifluoride and the bis(cyanopropyl)tetramethyldisiloxane are reacted at a temperature of from about 60° C. to about 100° C. 
     
     
         13 . The method of  claim 10 , wherein the boron trifluoride and the bis(cyanopropyl)tetramethyldisiloxane are reacted at a molar ratio of from about 0.3:1 to about 1:1. 
     
     
         14 . The method of  claim 10 , wherein the reaction is carried out in an inert solvent capable of forming an azeotrope with water. 
     
     
         15 . The method of  claim 14 , wherein the inert solvent is toluene. 
     
     
         16 . The method of  claim 14 , wherein a reaction product containing 3-cyanopropyldimethylfluorosilane, inert solvent and water is obtained and the reaction product is subjected to distillation wherein water is removed by azeotropic 
     
     
         17 . A method of making 3-cyanopropyldifluoromethylsilane comprising a step of reacting allyl cyanide and difluoromethylsilane. 
     
     
         18 . The method of  claim 17 , additionally comprising an initial step of obtaining the ditluoromethylsilane by reacting 2,4,6,8-tetramethylcyclotetrasiloxane and boron trifluoride. 
     
     
         19 . The method of  claim 17 , wherein the allyl cyanide and difluoromethylsilane are reacted in the presence of a hydrosilylation catalyst at a temperature of from about 70° C. to about 110° C. 
     
     
         20 . The method of  claim 17 , wherein the allylyanide and difluoromethylsilane are reacted in the presence of a hydrosiiylation catalyst. 
     
     
         21 . The method of  claim 20 , wherein the hydrosilylation catalyst is Karstedt's catalyst. 
     
     
         22 . The method of  claim 17 , wherein the allyl cyanide and difluoronaethylsilane are reacted at a molar ratio of from about 0.7:1 to about 1.3:1. 
     
     
         23 . A method of making a cyanoalkyldifluoromethylsilane, comprising a step of reacting a cyanoalkyldichloromethylsilane with ammonium bifluoride. 
     
     
         24 . The method of  claim 23 , wherein the cyanoalkyldichloromethylsilane is selected from the group consisting of 3-cyanopropyldichloromethylsilane and 2-cyanoethyldichloromethylsilane. 
     
     
         25 . The method of  claim 23 , wherein the cyanoalkyldichloromethylsilane and ammonium bifluoride are reacted at a molar ratio of from about 0.5 to about 1.5 moles of ammonium bifluoride per mole of cyanoalkyldichloromethylsilane. 
     
     
         26 . The method of  claim 23 , wherein the reaction is carried out in an inert solvent capable of forming an azeotrope with water. 
     
     
         27 . The method of  claim 26 , wherein the inert solvent is toluene. 
     
     
         28 . The method of  claim 26 , wherein a reaction product containing cyanoalkyldifluoromethylsilane, inert solvent and water is obtained and the reaction product is subjected to distillation wherein water is removed by azeotropic 
     
     
         29 . A method of making difluoromethylsilane, comprising reacting a cyclic siloxane and boron trifluoride, wherein the cyclic siloxane contains silicon atoms bearing —H and —CH 3  groups as substituents. 
     
     
         30 . The method of  claim 29 , wherein the boron trifluoride is in the form of an etherate complex. 
     
     
         31 . The method of  claim 29 , wherein from about 0.5 to about 1 mole of boron trifluoride per mole of Si present in the cyclic siloxane are reacted, 
     
     
         32 . The method of  claim 29 , wherein boron trifluoride and the cyclic siloxane are reacted at a temperature of from about 50° C. to about 100° C.