Method of preparing organo dialkylalkoxysilane

Abstract

The invention relates to the preparation of organodialkylalkoxysilane using a continuous method consisting in bringing an alkanol into continuous contact with an omega-haloalkyl dialkylhalosilane in a countercurrent reactor, such as a plate column or a packed column. The reaction is performed in the aforementioned countercurrent reactor in the presence or absence of a non-reactive solvent with scavenging of the hydrochloric acid formed. The omega-haloalkyl dialkylalkoxysilane thus formed is particularly suitable for use as a starting material for the preparation of organosilicon compounds containing sulphur having general formula (I) by means of sulphidisation reaction on an alkaline metal polysulphide.

1 - 19 . (canceled)  
     
     
         20 . A process for preparing bis(monoorganoxysilylpropyl)polysulfides of formula:  
       
         
           
           
               
               
           
         
       
       in which: 
 x is an integral or fractional number ranging from 1.5±0.1 to 5±0.1; and  
 the symbols R 1 , which are identical or different, each represent a monovalent hydrocarbon group selected from a linear or branched alkyl radical having 1 to 15 carbon atoms and a linear or branched alkoxyalkyl radical having 2 to 8 carbon atoms;  
 the symbols R 2  and R 3 , which are identical or different, each represent a monovalent hydrocarbon group selected from a linear or branched alkyl radical having 1 to 6 carbon atoms and a phenyl radical;  
 said process being performed by carrying out the following steps:  
 a) carrying out the following equation:  
                     
 in which formulae:  
 the symbol Hal represents a halogen atom selected from chlorine, bromine and iodine atoms,  
 the symbols R 2  and R 3  are as defined above, and  
 A represents a removable group selected alternatively from: a halogen atom Hal belonging to chlorine, bromine and iodine atoms, or a radical para-R 0 —C 6 H 4 —SO 2 —O— wherein R 0  is a linear or branched C1-C4 alkyl radical, or a radical R 0 —SO 2 —O— wherein R 0  is as defined above, or a radical R 0 —CO—O— wherein R 0  is as defined above, by reacting, at a temperature ranging from −10° C. to 200° C., one mole of the diorganohalosilane of formula (V) with a molar amount being stoichiometric or different from the stoichiometry of the allyl derivative of formula (VI), in a homogeneous or heterogeneous medium in the presence of an initiator being:  
 either of a catalytic activator consisting of: (i) at least one catalyst comprising at least one transition metal or one derivative of said metal, taken from the group consisting of Co, Ru, Rh, Pd, Ir and Pt; and optionally (2i) at least one hydrosilylation reaction promoter,  
 or of a photochemical activator, and, optionally,  
 by isolating the diorganohalosilylpropyl derivative of formula (VII) that is formed b) preparing an organodialkylalkoxysilane of formula (IX):  
   R 1 O—(R 2 R 3 )Si—(CH 2 ) 3 -A  
 By continuously contacting an alcohol of formula (VIII): R 1 —OH in countercurrent with a silane of formula (VII): Hal-(R 2 R 3 )Si—(CH 2 ) 3 -A,  
 in order to carry out the alcoholysis reaction of said silane according to the following reaction:  
   Hal-(R 2 R 3 )Si—(CH 2 ) 3 -A+R 1 —OH→R 1 O—(R 2 R 3 )Si—(CH 2 ) 3 -A+H-Hal  (VII) (VIII) (IX)  
 the operation being carried out with stripping of the product of formula H-Hal formed, and  
 c), proceeding according to the following equation:  
                     
 wherein:  
 the symbols R 1 , R 2 , R 3 , A and x are as defined above and  
 the symbol M represents an alkali metal,  
 the reaction being carried out: 
 by reacting, at a temperature ranging from 20° C. to 120° C., either the reaction mixture obtained at the end of step (b) as defined in  claim 20 , or the monoorganoxydiorganosilylpropyl derivative of formula (IX), taken in isolation after separation from said reaction mixture, with the metal polysulfide of formula (X) in the anhydrous state, using 0.5±15 mol % of metal polysulfide of formula (X) per mole of the reactant of formula (IX) and optionally operating in the presence of an inert polar (or nonpolar) organic solvent, and  
 by isolating the bis(monoorganoxysilylpropyl)polysulfide of formula (I) that is formed.  
 
 
     
     
         21 . The process according to  claim 20 , wherein step (a) is carried out by operating in the presence of a catalytic activator which comprises, as the catalyst(s) (i), one and/or other of the following metal species: (i-1) at least one finely divided elemental transition metal; and/or (i-2) a colloid of at least one transition metal; and/or (i-3) an oxide of at least one transition metal; and/or (i-4) a salt derived from at least one transition metal and a mineral or carboxylic acid; and/or (i-5) a complex of at least one transition metal equipped with organic ligand(s) possessing one or more heteroatoms and/or organosilicon ligands; and/or (i-6) a salt as defined above in which the metal moiety is equipped with ligand(s) as also defined above; and/or (i-7) a metal species selected from elemental transition metal, oxide, salt, complex, complexed salt wherein the transition metal is combined with at least one other metal selected from the class of the elements of groups 1b, 2b, 3a, 3b, 4a, 4b, 5a, 5b, 6b, 7b and 8 with the exception of Co, Ru, Rh, Pd, Ir and Pt, of the Periodic Table, said other metal being taken in its elemental form or in a molecular form.  
     
     
         22 . The process according to  claim 21 , wherein step (a) is carried out by operating in the presence of a catalytic activator which comprises, as the catalyst (or catalysts) (i), one and/or other of the metal species (i-1) to (i-8) wherein the transition metal belongs to the subgroup formed by Ir and Pt.  
     
     
         23 . The process according to  claim 22 , wherein step (a) is carried out by operating in the presence of a catalytic activator which comprises, as the catalyst (or catalysts) (i), one and/or other of the metal species (i-1) to (i-8) where the transition metal is Ir.  
     
     
         24 . The process according to  claim 23 , wherein step (a) is carried out by operating in the presence of a catalytic activator which comprises, as the catalyst (or catalysts) (i), at least one metal species of type (i-5) belonging to the iridium complexes of formula:  
         [Ir(R 4 )Hal] 2   (XI)  
       wherein: 
 the symbol R 4  represents a conjugated or nonconjugated, linear or cyclic (mono- or polycyclic) polyene ligand having 4 to 22 carbon atoms and from 2 to 4 ethylenic double bonds; and  
 the symbol Hal is as defined above.  
 
     
     
         25 . The process according to  claim 20 , wherein step (c) is carried out by deploying anhydrous metal polysulfides of formula (X) which are prepared beforehand from an alkali metal sulfide M 2 S in the form of a hydrated sulfide, according to a procedure which consists in linking together the following operating phases (1) and (2): 
 phase (1), where the alkali metal sulfide hydrate is dehydrated by applying the appropriate method which makes it possible to remove the water of crystallization while retaining the alkali metal sulfide in the solid state throughout the dehydration phase; and    phase (2), where subsequently one mole of dehydrated alkali metal sulfide obtained is contacted with n(x−1) moles of elemental sulfur, the operating being carried out at a temperature ranging from 20° C. to 120° C., optionally under pressure and optionally again in the presence of an anhydrous organic solvent, the aforementioned factor n being situated within the range from 0.8 to 1.2 and the symbol x being as defined above.    
     
     
         26 . The process according to  claim 25 , wherein the products corresponding to formulae (I), (V), (VI), (VII), (VIII) and (IX) have ethyl groups R 1  and methyl groups R 2  and R 3  and A and Hal represent a chlorine atom.