# Patent

## Title
Silicone condensation reaction

## Abstract

A new silicone condensation reaction, the condensation between an alkoxy silane or siloxane and an organo-hydrosilane or siloxane and catalysts therefore is described and claimed.

## Background
The present invention relates to a new condensation reaction between compounds containing the hydrogen bonded directly to silicon (organo-hydrosilanes or organo-hydrosiloxanes) and alkoxy-silane or siloxane which leads to the formation of siloxane bond and release of hydrocarbons as a by-product.
BACKGROUND OF THE INVENTION
Two general processes can be applied for synthesis of organosiloxane polymers; ring opening polymerization of cyclic siloxanes and polycondensation. The polycondensation reaction between organofunctional silanes or oligosiloxanes leads to the formation of siloxane bond and elimination of a low molecular byproduct. The polycondensation of low molecular weight siloxanol oils is the most common method synthesis of polyorganosiloxanes and has been practiced for several years. The byproduct of this process is water. Unfortunately this method cannot be used for the synthesis of well-defined block organosiloxane copolymers. In that case the non-hydrolytic condensation processes can be employed. Many of such reactions are known and are frequently used:

    1) the reaction of an organohalosilane with an organoalkoxysilane,

≡Si—X+R—O—Si≡→≡Si—O—Si≡+RX;

    2) the reaction of organohalosilanes with organoacyloxysilanes,

≡Si—X+RCOO—Si≡→≡Si—O—Si≡+RCOX;

    3) the reaction of organohalosilanes with organosilanols,

≡Si—X+HO—Si≡→≡Si—O—Si≡+HX;

    4) the reaction of organohalosilanes with metal silanolates,

≡Si—X+Metal-O—Si≡→≡Si—O—Si≡+MetalX;

    5) the reaction of organo-hydrosilanes with organosilanols,

≡Si—H+HO—Si≡→≡Si—O—Si≡+H2;

    6) the self-reaction of organoalkoxysilanes,

≡Si—OR+RO—Si≡→≡Si—O—Si≡+ROR

    7) the reaction of organoalkoxysilanes with organoacyloxysilanes,

≡Si—OR+R′COO—Si≡→≡Si—O—Si≡+R′COOR

    8) the reaction of organoalkoxysilanes with organosilanols,

≡Si—OR+HO—Si≡→≡Si—O—Si≡+ROH

    9) the reaction of organoaminosilanes with organosilanols,

≡Si—NR2+HO—Si≡→≡Si—O—Si≡+NR2H;

    10) the reaction of organoacyloxysilanes with metal silanolates,

≡Si—OOR+Metal-O—Si≡→≡Si—O—Si≡+MetalOOR;

    11) the reaction of organoacyloxysilanes with organosilanols,

≡Si—OOR+HO—Si≡→≡Si—O—Si≡+HOOR;

    12) the reaction of organooximesilane with organosilanols,

≡Si—ON═OR2+HO—Si≡→≡Si—O—Si≡+HN═OR2;

    13) the reaction of organoenoxysilane with organosilanols,

≡Si—O(C═CH2)R+HO—Si≡→≡Si—O—Si≡+CH3COR;



Those reactions can also be used for the formation of siloxane networks via a crosslinking process. Many of the above processes require the presence of catalyst such as protic acids, Lewis acids, organic and inorganic bases, metal salts and organometalic complexes. (See, for example, (a) “The Siloxane Bond” Ed. Voronkov, M. G.; Mileshkevich, V. P.; Yuzhelevskii, Yu. A. Consultant Bureau, New York and London, 1978; and (b) Noll, W. “Chemistry and Technology of Silicones”, Academia Press, New York, 1968).
It is also well known in silicon chemistry that the organosilanol moiety will react with a hydrogen atom bonded directly to silicon (organo-hydrosilane) to produce a hydrogen molecule and the silicon-oxygen bond, (See, “Silicon in Organic, Organometallic and Polymer Chemistry” Michael A. Brook, John Wiley & Sons, Inc., New York, Chichester, Weinheim, Brisbane, Singapore, Toronto, 2000). Although the uncatalyzed reaction will run at elevated temperatures, it is widely known that this reaction will run more readily in the presence of a transition metal catalyst especially noble metal catalysts such as those comprising platinum, palladium, etc., a basic catalyst such as an alkali metal hydroxide, amine, etc., or a Lewis acid catalyst such as a tin compound, etc. Recently it has been reported that organo-boron compounds are extremely efficient catalysts for the reaction between an organo-hydrosilanes and organosilanols (WO 01/74938 A1). Unfortunately, the by-product of this process is dangerous, highly reactive hydrogen.
In spite of the foregoing developments, there is a continuing search for new condensation reactions that will improve reaction's selectivity and safety of the polycondensation process.
SUMMARY OF THE INVENTION
The present invention provides for a new condensation process to forming a silicon-oxygen bond comprising reacting an organosilane or siloxane compounds bearing at least one hydrosilane functional group with an organoalkoxysilane or siloxane compounds containing at least one alkoxysilane functional group and release of hydrocarbon as a byproduct, in the presence of a Lewis acid catalyst. The present invention also provides for the formation of silicon-oxygen bond by reacting a compound comprising both at least one hydrosilane functionality and at least one an alkoxysilane moiety and releases hydrocarbon as a byproduct in the presence of a Lewis acid catalyst.
Thus the present invention provides for a process for forming a silicon to oxygen bond comprising: (a) reacting a first silicon containing compound said first silicon containing compound comprising a hydrogen atom directly bonded to a silicon atom with (b) a second silicon containing compound said second silicon containing compound comprising an alkoxy group bonded to a silicon atom, in the presence of (c) a Lewis acid catalyst thereby forming a silicon to oxygen bond. The present invention also provides for a process for forming an silicon to oxygen bond comprising: (a) selecting a compound comprising both at least one hydrogen atom directly bonded to a silicon atom and at least one an alkoxy group bonded to a silicon atom in said compound and (b) reacting the hydrosilane functional group with the alkoxysilane group, in the presence of (c) a Lewis acid catalyst thereby forming a silicon to oxygen bond. The processes of the present invention further provide for means to produce compositions: siloxane foams, hyperbranched silicone polymers, cross-linked siloxane networks and gels therefrom as well as other silicone and siloxane molecules exemplified herein.


DETAILED DESCRIPTION OF THE INVENTION
The present invention represents the discovery of a new type of non-hydrolytic condensation reaction for silicon bearing molecules. Generally, the reaction may be characterized as a condensation reaction between an organo hydrosilane or siloxane compounds bearing at least one hydrosilane moiety with an organoalkoxysilane or siloxane compounds containing at least one alkoxysilane moiety or functionality in the following exemplary embodiment: the reaction of (MaDbTcQd)e(R2)f(R3)gSiOCH2R1 and HSi(R4) h(R5)i(MaDbTcQd)j yields a compound containing a new silicon-oxygen bond (MaDbTcQd)e(R2)f(R3)gSiOSi(R4)h(R5)i(MaDbTcQd)j and hydrocarbon (CH3R1) as the products. The subscripts a, b, c and d are independently zero or positive number; e, f, g, h, i, j are zero or positive number subject to limitation that e+f+g=3; h+i+j=3; j=0, 1, 2; i=0, 1, or 2 subject to the limitation that i+j≦2. The other molecular components have standard definitions as follows:

M=R6R7R8SiO1/2;

D=R9R10SiO2/2;

T=R11SiO3/2; and

Q=SiO4/2

or drawn as structures (without any implied limitations of stereochemistry):





The R1 substituent is hydrogen or is independently selected from the group of one to sixty carbon atom monovalent hydrocarbon radicals that may or may not be substituted with halogens (halogen being F, Cl, Br and I), e.g. non limiting examples being fluoroalkyl substituted or chloroalkyl substituted, substituents R2, R4, R6, R7, R8, R9, R10, and R11 are independently selected from the group of one to sixty carbon atom monovalent hydrocarbon radicals that may or may not be substituted with halogens (halogen being F, Cl, Br and I), e.g. non limiting examples being fluoroalkyl substituted or chloroalkyl substituted and R3 and R5 are independently selected from the group consisting of hydrogen, one to sixty carbon atom monovalent alkoxy radicals, one to sixty carbon atom monovalent aryloxy radicals, one to sixty carbon atom monovalent alkaryloxy radicals and halogen.
Condensation of molecules that bear both functionalities, one (≡SiOCH2R1) and one (H—Si≡), on the same molecular backbone will lead to a formation of linear polymers unless the condensation reaction is conducted with a highly diluted substrate, in which case cyclic condensation products would be expected. Molecules that bear more than one (≡SiOCH2R1) and only one (H—Si≡) functionalities on the same molecular backbone as well as molecules that bear one (≡SiOCH2R1) and more than one (H—Si≡) functionalities on the same molecular backbone are examples of ABx molecular structures. The condensation of these ABx compounds will lead to a formation of complex hyperbranched condensation polymers. The examples of such ABx molecular structures include but are not limited to:




Condensation of siloxane oligomers and polymers that bear more than one (≡SiOCH2R1) functional group with the siloxane oligomers and polymers having more than one (H—Si≡) functionality is also possible and will lead to a formation of the cross-linked network. A preferred structure of the polymers with (≡SiOCH2R1) groups has the following formula:




where

G is OCH2R1; R1, R2, R4 has been defined before, m=0, 1, 2 . . . 5000; n=0, 1, 2 . . . 1000; o=1, 2, 3; p=0, 1, 2, 3; r=0, 1, 2 with limitation that r+o=2 for internal siloxane and p+o=3 for terminal siloxane units.
A preferred structure of the polymer with (≡Si—H) groups has the following formula:




where

R1, R2, R4 has been defined before, m=0, 1, 2 . . . 1000; n=0, 1, 2 . . . 100; t =0, 1, 2, 3 s=0, 1, 2, 3 with the limitation that t+s=2 for internal siloxane units and t+s=3 for terminal siloxane units.
Other preferred compounds with (≡Si—H) groups are:
Cyclic Siloxanes:




where R2 has been defined before and u=1, 2, 3, . . . 8; or branched siloxane:





where R2 has been defined before and v=0, 1; w=3, 4

Condensation of siloxane oligomers and polymers that bear more than one (≡SiOCH2R1) moiety and more than one (H—Si≡) functionality is also possible and will lead to formation of a cross-linked network.
The above reaction is generally accomplished in the presence of an appropriate catalyst. The catalyst for this reaction is preferably a Lewis acid catalyst. For the purposes herein, a “Lewis acid” is any substance that will take up an electron pair to form a covalent bond (i.e., “electron-pair acceptor”). This concept of acidity also includes the “proton donor” concept of the Lowry-Bronsted definition of acids. Thus boron trifluoride (BF3) is a typical Lewis acid, as it contains only six electrons in its outermost electron orbital shell. BF3 tends to accept a free electron pair to complete its eight-electron orbital. Preferred Lewis acid catalysts include such catalysts as FeCl3, AlCl3, ZnCl2, ZnBr2, BF3. The ability of any particular Lewis acid to catalyze the new reaction of the present invention will be a function of acid strength, steric hindrance of both the acid and the substrate and solubility of the Lewis acid and the substrate in the reaction medium. Generally the following Lewis acids: FeCl3, AlCl3, ZnCl2, ZnBr2, and BF3 are only sparingly soluble in siloxane solvents and this low solubility tends to interfere with the ability of these particular Lewis acid catalysts to catalyze the desired reaction. Lewis acid catalysts having a greater solubility in siloxane media are more preferred and preferable catalysts include Lewis acid catalysts of formula (I)

MR12xXy  (I)

wherein M is B, Al, Ga, In or Tl; each R12 is independently the same (identical) or different and represent a monovalent aromatic hydrocarbon radical having from 6 to 14 carbon atoms, such monovalent aromatic hydrocarbon radicals preferably having at least one electron-withdrawing element or group such as —CF3, —NO2 or —CN, or substituted with at least two halogen atoms; X is a halogen atom; x is 1, 2, or 3; and y is 0, 1 or 2; with the proviso that x+y=3, more preferably a Lewis acid of Formula (II)

BR13xXy  (II)

wherein each R13 are independently the same (identical) or different and represent a monovalent aromatic hydrocarbon radical having from 6 to 14 carbon atoms, such monovalent aromatic hydrocarbon radicals preferably having at least one electron-withdrawing element or group such as —CF3, —NO2 or —CN, or substituted with at least two halogen atoms; X is a halogen atom; x is 1, 2, or 3; and y is 0, 1 or 2; with the proviso that x+y=3, and is most preferably B(C6F5)3.

The condensation reaction between the (≡Si—H) moiety and the (≡SiOR) moiety has some limitations, it appears that when three electron withdrawing substituents are on the silicon containing (≡Si—H) bond such as for example —OR, siloxane substituents or X (X=halogen) the reaction kinetics are slowed, sometimes to the point of inhibition of the reaction. Also the condensation reaction appears to require an alkoxy silane of the following structure (≡Si—O—CH2—R1) wherein R1 is C1-60 alkyl, C1-60 alkoxy, C2-60 alkenyl, C6-60 aryl, and C6-60 alkyl-substituted aryl, and C6-60 arylalkyl where the alkyl groups may be halogenated, for example, fluorinated to contain fluorocarbons such as C1-22 fluoroalkyl. The preferred alkoxy group is methoxy and ethoxy group.
The process of the present invention utilizes a Lewis acid catalyst concentration that ranges from about 1 part per million by weight to about 10 weight percent (based on the total weight of siloxanes being reacted); preferably from about 10 part per million by weight (wppm) to about 5 weight percent (50,000 wppm), more preferably from about 50 wppm to about 10,000 wppm and most preferably from about 50 wppm to about 5,000 wppm.
The condensation reaction can be done without solvent or in the presence of solvents. The presence of solvents may be beneficial due to an increased ability to control viscosity, rate of the reaction and exothermicity of the process. The preferred solvents include aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, as well as oligomeric cyclic diorganosiloxanes.
The condensation reaction between the (≡Si—H) moiety and the (≡SiOCH2R1) moiety can be conducted at an ambient or at an elevated temperature depending on the chemical structures of reagents and catalysts, concentration of catalyst and used solvent.
In some cases it is desirable to blend siloxane oligomers or polymers that bear at least one (≡SiOCH2R1) moiety with the siloxane oligomers or polymers having at least one (H—Si≡) functional group and Lewis acid catalyst. Subsequently the condensation reaction may be activated by heat. To extend the pot life of such a fully formulated mixture, the addition of a stabilizing agent is recommended. The stabilizing additives that are effective belong to the group of nucleophiles that are able to form a complex with Lewis acids. These stabilizing additives, preferably nucleophilic compounds, include but are not limited to ammonia, primary amines, secondary amines, tertiary amines, organophosphines and phosphines.
The compositions produced according to the method or process of this invention are useful in the field of siloxane elastomers, siloxane coatings, insulating materials and cosmetic products. The condensation reaction of (≡Si—H) terminated dimethylsiloxane oligomers with alkoxy-terminated diphenylsiloxane oligomers leads to a formation of regular block siloxane copolymers with beneficial thermo-mechanical properties. The crosslinked material produced via condensation of siloxane oligomers and polymers that bear more than one (≡SiOCH2R1) moiety with the siloxane oligomers and polymers having more than one (H—Si≡) functional group will lead to a formation of novel siloxane coatings and siloxane foams. A low cross-link density network frequently has the ability to be swollen by lower molecular weight siloxanes or hydrocarbons thereby forming a gel. Such gels have found utility as silicone structurants for cosmetic compositions. Hyperbranched siloxane polymers may be prepared by reacting the self-condensation of molecule that bears more than one (≡SiOCH2R1) and one (H—Si≡) functionalities in the presence of Lewis acid.
It is to be noted that silicon is a tetravalent element and for purposes of descriptive convenience herein, not all four bonds of the silicon atom have been described in some of the abbreviated chemical reaction scenarios used to explain the reaction chemistry involved in the formation of non-hydrolytic silicon oxygen bonds. Where silicon is hypovalent or hypervalent in terms of its customary stereochemistry, the full structure has been indicated.
EXPERIMENTAL


    1. Reaction of MDH25D25M with Me2Si(OEt)2.


A 50 ml flask was charged with 7.5 g of MDH25D25M (0.057 mol of Si—H) and 3 g of Me2Si(OEt)2 (0.02 mol). The resulting low viscosity homogenous fluid was heated to 100 g for 1 hr. No reaction was observed. This example demonstrates that the reaction requires appropriate catalysis.

    2. Reaction of MDH25D25M with MeSi(OEt)3 in the presence of B(C6F5)3 


A 50 ml flask was charged with 7.5 g of MDH25D25M (0.057 mol of Si—H) and 3 g of MeSi(OEt)3 (0.02 mol). The reagents were mixed to form a low viscosity homogenous fluid. 1000 ppm of B(C6F5)3 as a 1.0 wt % solution in methylene chloride, was added to the flask. The resulting mixture was stable at room temperature for several hours. After heating to 80° C. a very violent reaction occurred with rapid evolution of gas. The reaction mixture turned into foam in few seconds. This example shows that addition of a suitable borane catalyst, B(C6F5)3, promotes an rapid reaction between Si—H and SiOR. Conceivably this system could be used to make a siloxane foam.

    3. Self Condensation of (CH3)2Si(H)(OC2H5)


A 50 ml flask was charged with 10 g of dry toluene and 5.0×10−6 moles of B(C6F5)3 The resulting mixture was heated to 50° C. Next 5.2 g (0.05 moles) of (CH3)2Si(H)(OEt) was added dropwise over a period of 30 minutes. The exothermic reaction with gas evolution stared after addition of first few drops of alkoxy silane. The rate of addition was adjusted to keep the reaction mixture temperature below 90° C. After addition was completed, the resulting mixture was heated at 50° C. for an additional 60 minutes. The proton NMR showed 100% conversion of Si—H and 90% conversion of Si—OEt. Si29 NMR indicated the formation of linear alkoxy-stopped siloxane oligomers along with small amounts of D3 (hexamethylcyclotrisiloxane) and D4 (octamethyl cyclotetrasiloxane). This low temperature process may also be carried out a room temperature.

    4. Self Condensation of (CH3)Si(H)(OCH3)2 


A 50 ml flask was charged with 10 g of dry toluene and 5.0×10−6 moles of B(C6F5)3. The resulting mixture was heated to 50° C. Next 5.3 g (0.05 moles) of (CH3)Si(H)(OCH3)2 was added dropwise over a period of 30 minutes. The exothermic reaction with gas evolution started after the addition of the first few drops of alkoxy silane. The rate of addition was adjusted to keep a mixture temperature below 90° C. After addition was completed, the resulting mixture was heated at 50° C. for an additional 60 minutes. The proton NMR showed 100% conversion of Si—H and 50% conversion of Si—OCH3. Si29 NMR indicated formation of hyperbranched siloxane oligomers with Si—OCH3 end groups.

    5. Self Condensation of HSi(OC2H5)3 


A 50 ml flask was charged with 10 g of dry toluene and 5.0×10−6 moles of B(C6F5)3. The resulting mixture was heated to 50° C. Next 7.9 g (0.05 moles) of HSi(OC2H5)3 was added drop wise over a period of 30 minutes. The reaction temperature did not change, any gas evolution was observed. After addition of alkoxysilane was completed the resulting mixture was heated at 50° C. for an additional 60 minutes. The proton NMR showed 0% conversion of Si—H.

    6. Condensation of (CH3O)2Si(C6H5)2 with H—Si(CH3)2—O—Si(CH3) 2—H


A 50 ml flask was charge with 10 g of dry toluene and 5.0×10−6 moles of B(C6F5)3.
The resulting mixture was heated to 50° C. Next a mixture of 4.88 g (0.02 moles) of (CH3O)2Si(C6H5)2 and 2.68 g (0.02 moles) of H—Si(CH3)2—O—Si(CH3)2—H was added drop wise over a period of 30 minutes. The exothermic reaction with gas evolution stared after addition of the first few drops. After addition was completed the resulting mixture was heated at 50° C. for an additional 60 minutes. The proton NMR showed 100% conversion of Si—H and 100% conversion of Si—OCH3. Si29 NMR indicated formation of cyclic compound (Si(C6H5)2—O Si(CH3)2—O—Si(CH3)2—O)— and linear oligomers.

    7. Condensation of (CH3O)2Si(C6H5)2 with H—Si(CH3)2—Cl


A 50 ml flask was charged with 10 g of dry toluene, 2.93 g (0.03 moles) of HSi(CH3)2—Cl and 5.0×10−6 moles of B(C6F5)3 and cooled down to 20° C. Next a mixture of 3 g (0.012 moles) of (CH3O)2Si(C6H5)2 and 3.0 g of toluene was added drop wise over a period of 30 minutes. The exothermic reaction with gas evolution stared after addition of the first drop. After addition was completed the resulting mixture was heated at 50° C. and low boiling components were stripped by application of a partial vacuum. The proton NMR showed 100% conversion of Si—H and formation of chloro-stopped siloxane (ClSi(CH3)2—O—S(C6H5)2—O—Si(CH3)2Cl). Si29 NMR confirmed formation of this compound.

    8. Condensation of ((CH3)2CHO)2SiC2H3 with H—Si(CH3)2—O—Si(CH3) 2—H 


A 50 ml flask was charged with log of dry toluene and 5.0×10−6 moles of B(C6F5)3. The resulting mixture was heated to 50° C. Next a mixture of 4.64 g (0.02 moles) of (iPrO)3SiVi and 1.34 g (0.01 mol) of H—Si(CH3)2—O—Si (CH3)2—H was added drop wise over a period of 5 minutes. The reaction temperature did not change, and no gas evolution was observed. After addition of regents was completed the resulting mixture was heated at 50° C. for additional 60 min. The GC analysis did not show formation of siloxane oligomers. Example 8 shows that sterically hindered alkoxysilanes such as isopropoxysilane or t-butyloxysilane do not react with Si—H in the presence of B(C6F5)3. The condensation reaction requires the presence of —O—CH2—R1 alkoxide moiety attached to silicon atom.

    9. Reaction of MDH25D25M with MeSi(OMe)3 in the presence of B(C6F5)3 


A 10 ml flask was charged with 1.25 g of MDH25D25M (0.01 moles of Si—H) and an appropriate amount of MeSi(OMe)3. The reagents were mixed to form a low viscosity homogenous fluid. Next 160 ppm of B(C6F5)3 was added. The cure kinetics of the above mixture was evaluated by differential scanning calorimetry (DSC: Perkin Elmer). The observed pot life, peak temperature and Delta H are presented in the following table:


















Peak
Delta
Pot


Exp. #
Formula
SiH/SiOR
temp
H J/g
life/min




















091-c
884466-MeSi(OMe)3
0.63
53.4
561
>360


091-d
884466-MeSi(OMe)3
1.8
61.5
174
45


091-e
884466-MeSi(OMe)3
1
57.4
310
>360









    10. Reaction of MDH25D25M with OctylSi(OMe)3 in the presence of B(C6F5)3 


A 10 ml flask was charged with 1.25 g of MDH25D25M (0.01 moles of Si—H) and appropriate amount of (C8H17)Si(OMe)3. The reagents were mixed to form a low viscosity homogenous fluid. Next 160 ppm of B(C6F5)3 was added. The cure kinetics of the above mixture was evaluated by differential scanning calorimetry (DSC: Perkin Elmer). The observed pot life, peak temperature and Delta H are presented in the following table:


















Peak
Delta



Exp. #
Formula
SiH/SiOR
temp
H J/g
Pot life/min




















091-f
884466-OctSi(OMe)3
1
47.5
745
20


091-g
884466-OctSi(OMe)3
0.66
62
196
20


091-h
884466-OctSi(OMe)3
1.25
36.7
490
10









Examples 9 and 10 show that a mixture of Si—H siloxane with alkoxysilane in the presence of a catalytic amount of B(C6F5)3 is stable at room temperature for a period ranging from 10 min to more than 6 hours. The room temperature stable mixture can be quickly reacted at slightly elevated temperature. These experiments indicate that the mixtures from examples 9 and 10 could be used to produce thin siloxane coatings at a low temperature (below 80° C.). Such properties would be useful for low temperature paper release coatings and applications thereof.
The foregoing examples are merely illustrative of the invention, serving to illustrate only some of the features of the present invention. The appended claims are intended to claim the invention as broadly as it has been conceived and the examples herein presented are illustrative of selected embodiments from a manifold of all possible embodiments. Accordingly it is Applicants' intention that the appended claims are not to be limited by the choice of examples utilized to illustrate features of the present invention. As used in the claims, the word “comprises” and its grammatical variants logically also subtend and include phrases of varying and differing extent such as for example, but not limited thereto, “consisting essentially of” and “consisting of.” Where necessary, ranges have been supplied, those ranges are inclusive of all sub-ranges there between. It is to be expected that variations in these ranges will suggest themselves to a practitioner having ordinary skill in the art and where not already dedicated to the public, those variations should where possible be construed to be covered by the appended claims. It is also anticipated that advances in science and technology will make equivalents and substitutions possible that are not now contemplated by reason of the imprecision of language and these variations should also be construed where possible to be covered by the appended claims. All United States patents referenced herein are herewith and hereby specifically incorporated by reference.

## Claims

1. A process for forming a silicon to oxygen bond in a compound comprising:
a) selecting a compound comprising both a hydrogen atom directly bonded to a first silicon atom and an alkoxy group bonded to a second silicon atom in said compound and
b) reacting the hydrosilane moiety with the silicon-alkoxy group, in the presence of
c) a Lewis acid catalyst thereby forming a silicon to oxygen bond.

2. The process of claim 1 wherein the Lewis acid catalyst comprises a compound of the formula:


MR12xXy


wherein M is selected from the group consisting of B, Al, Ga, In and Tl; each R12 is independently selected from the group of monovalent aromatic hydrocarbon radicals having from 6 to 14 carbon atoms; X is a halogen atom selected from the group consisting of F, Cl, Br, and I; x is 1,2, or 3; and y is 0, 1 or 2; subject to the requirement that x+y=3.

3. The process of claim 2 where M is boron.

4. The process claims 3 wherein each R12 is C6F5 and x=3.

5. The process of claim 1 wherein the concentration of the Lewis acid catalyst ranges from about 10 wppm to about 50,000 wppm.

6. The process of claim 1 wherein said process is stabilized by the addition of a compound selected from the group consisting of ammonia, primary amines, secondary amines, tertiary amines, organophosphines and phosphines.

7. The process of claim 1 wherein said process is activated by heat.

8. A process for the preparation of hyperbranched siloxane polymers utilizing the method of claim 1 wherein said compound comprises:
a) more than one hydrogen atom directly bonded to more than one first silicon atom and only one alkoxy group bonded to one second silicon atom; or alternatively said compound comprises
b) one hydrogen atom directly bonded to a first silicon atom and more than one alkoxy group bonded to more than one second silicon atom.