PROCESS FOR PRODUCING BIS-(AMINOALKYL)-POLYSILOXANES
Bis(aminoalkyl)siloxane dimers or oligomers are prepared by a process utilizing hydrosilation of an olefinic amine with tetraorganodisiloxane or with bis(dialkylhydrogen)siloxane oligomers to generate high purity bis(aminoalkyl)disiloxane or bis(aminoalkyl)siloxane oligomers at high conversion yield, which may then be subsequently equilibrated to higher molecular weight bis(aminoalkyl)polysiloxanes.
1 . A batch or continuous process for preparing bis(aminoalkyl)disiloxanes or bis(aminopropyl)siloxane oligomers or bis(aminoalkyl)polysiloxanes,said process conducted in an inert atmosphere comprising:
(A) silylating an olefinic amine (Reagent A) of the formula
wherein each R 1 is independently hydrogen, C 1-4 primary or secondary alkyl, phenyl or substituted phenyl, with a trimethylsilyl protection group from a trimethyl silylation agent (Reagent B), in the presence of a catalytic amount of an acid catalyst (Reagent C), followed by stripping excess Reagent A from the silylated product,
(B) reacting the stripped product of the silylation reaction with at least one polydiorganohydrogensiloxane (Reagent D) of the formula
wherein R 2 is C 1-4 primary or secondary alkyl, phenyl, or substituted phenyl and x has a value of 1 to about 300, in the presence of a catalytic amount of a platinum-containing hydrosilation catalyst (Reagent E),
(C) deprotecting the amine group and forming the desired bis(aminoalkyl)disiloxane or bis(aminoalkyl)siloxane oligomer by hydrolysis with water or alcoholysis with alcohol and optionally in the presence of a catalytic amount of an alkali catalyst (Reagent F),
(D) recovering the trimethyl silyl protection groups in the form of hexamethyldisiloxane (deprotection by water hydrolysis) or in the form of trimethylalkoxysilane (deprotection with alcohol) by a distillation separation from the bis(aminopropyl)disiloxane or bis(aminopropyl)siloxane oligomer product, and
(E) equilibrating the purified bis(aminopropyl)disiloxane or bis(aminopropyl)siloxane oligomer with at least one polydiorganosiloxane (Reagent G) in the presence of a catalytic amount of an alkali catalyst (Reagent H) in an appropriate molar ratio to form the desired bis(aminoalkyl)polysiloxane.
2 . The process of claim 1 wherein Reagent A comprises at least one olefinic amine of formula I.
3 . The process of claim 2 wherein the olefinic amine is allylamine, methallylamine or 2-butenylamine.
4 . The process of claim 1 wherein Reagent B comprises at least one trimethyl silylation agent selected from the group of trimethylchlorosilane, trimethylalkoxysilane, hexamethyldisilazane, trimethylsilylamides, and trimethylsilylamines.
5 . The process of claim 1 wherein Reagent C comprises at least one acid catalyst suitable for promoting the trimethyl silylation reaction selected from the group of sulfuric acid, organosulfuric acid (e.g p-toluenesulfonic acid), hydrochloric acid, chlorosilanes, ammonium sulfate, ammonium chloride, and chloroacetic acids.
6 . The process of claim 5 wherein the chorosilane is trimethylchlorosilane when hexamethyldisilazane is used as the trimethyl silylation agent.
7 . The process of claim 1 wherein Reagent D comprises at least one polydiorganohydrogensiloxane of formula II.
8 . The process of claim 7 wherein x=1 and the polydiorganohydrogensiloxanes is 1,1,3,3-tetraalkyldisiloxane.
9 . The process of claim 8 wherein the 1,1,3,3-tetraalkyldisiloxane is 1,1,3,3-tetramethyldisiloxane.
10 . The process of claim 1 wherein Reagent E is a platinum-containing hydrosilation catalyst selected from the group consisting of chloroplatinic acid, chloroplatinic acid-olefin complexes, platinum complexes with olefins, platinum complexes with olefinic polysiloxanes, platinum on various supports such as alumina and silica, and platinum black.
11 . The process of claim 1 wherein Reagent F is a water soluble alkali metal, metal alkoxide, or ammonia base that may advantageously be used to promote hydrolysis or alcoholysis.
12 . The process of claim 1 wherein Reagent G is at least one polydiorganosiloxane selected from the group of cyclic siloxanes.
13 . The process of claim 12 wherein the cyclic polydimethylsiloxane is octamethylcyclotetrasiloxane.
14 . The process of claim 1 wherein Reagent H is a strong base equilibration catalyst employed for the polymerization of polyorganosiloxanes.
15 . The process of claim 14 wherein the strong base equilibration catalyst is selected from the group of hydroxides, phenolates, and silanolates (or siloxanolates) of the alkali metals; quaternary ammonium and phosphonium bases and their silanolates (or siloxanolates); 3-aminopropyl dimethyl tetramethylammonium silanolate, and 3-aminopropyl dimethyl tetrabutylphosphonium silanolate.
16 . The process of claim 1 wherein the bis(aminopropyl)polysiloxane equilibration of Step E has staged additions of cyclic polydiorganosiloxane and/or catalyst for higher molecular weight products above about a molecular weight of 2000 and staged additions of bis(aminopropyl)disiloxane or bis(aminopropyl)siloxane oligomer endstopper and/or catalyst for bis(aminopropyl)polysiloxane products below a molecular weight of about 2000.
17 . The process of claim 1 wherein the reactions are performed in the absence of an added solvent.
18 . The process of claim 1 wherein one or more of the reactions are performed in the presence of a hydrocarbon solvent.