Hydrosilylating an isolated monohydridosiloxane
View Patent ↗An asymmetric siloxane is made by reacting a silicone having the formula M H D x M′ H where M H is R 1 R 2 HSiO 1/2 , M′ H is R 4 R 5 HSiO 1/2 and x is an integer 0≦x≦10 under selective hydrosilylation conditions in the presence of a precious metal hydrosilylation catalyst, with a first olefinic compound and in a second step, a monohydridosiloxane produced in the first step is reacted under hydrosilylating conditions with another olefinic compound different from the first olefinic compound.
1. A method to make an asymmetric organosiloxane comprising in a first step, reacting a dihydridosiloxane under hydrosilylation conditions in the presence of a precious metal hydrosilylation catalyst, with an hydrocarbon or heterocarbon compound containing a terminal carbon to carbon double bond to form a monohydridosiloxane, isolating the monohydridosiloxane from the first step; and in a second step, hydrosilylating the isolated monohydridosiloxane with a second and different hydrocarbon or heterocarbon compound containing a terminal carbon to carbon double bond and in the presence of the same or different hydrosilylation catalyst under hydrosilylation conditions to form an asymmetrically substituted organosiloxane, wherein the asymmetric organosiloxane product contains at least one polyalkylene oxide group; wherein at least one hydrocarbon or heterocarbon compound comprises a polyalkylene oxide reactant comprising a polyether comprising a member selected from the group consisting of CH 2 ═CHCH 2 O(CH 2 CH 2 O) 8 H; CH 2 ═CHCH 2 O(CH 2 CH 2 O) 8 CH 3 ; CH 2 ═CHCH 2 O(CH 2 CH 2 O) 4 (CH 2 CH(CH 3 )O) 5 H; CH 2 ═CHO(CH 2 CH 2 O) 5 (CH 2 CH(CH 3 )O) 5 H; CH 2 ═C(CH 3 )CH 2 O(CH 2 CH 2 O) 4 (CH 2 CH(CH 3 )O) 5 C(═O)CH 3 ; and CH 2 ═CHCH 2 O(CH 2 CH 2 O) 5 (CH 2 CH(CH 3 )O) 2 (CH 2 CH(CH 2 CH 3 )O) 2 H.
2. The method of claim 1 , wherein a first step precious metal catalyst is tris(triphenylphosphine)rhodium chloride.
3. The method of claim 1 , wherein the monohydridosiloxane is reacted in the presence of a hexachloroplatinic acid catalyst.
4. The method of claim 1 , comprising isolating the monohydridosiloxane of the first step by distillation or stripping.
5. The method of claim 1 , wherein a molar ratio of the dihydridosiloxane compound to the hydrocarbon or heterocarbon compound in the first step hydrosilylation is 4:1 to 1.1:1.
6. The method of claim 1 , wherein the first step reaction is conducted at a temperature in a range of 20 to 80° C. and the second step hydrosilylation is conducted at a temperature of 80 to 100° C.
7. The method of claim 1 , wherein the first step reaction is conducted in a batch process, a continuous process, or by a staged temperature controlled addition of reactants.
8. The method of claim 1 , comprising maintaining temperature of the reaction first step at 70° C. or less.
9. The method of claim 1 , comprising maintaining temperature of the reaction first step at 70° C. or less by controlled addition of hydrocarbon or heterocarbon compound.
10. The method of claim 1 , comprising maintaining temperature of the reaction first step at 20-80° C.
11. The method of claim 1 , comprising maintaining temperature of the reaction first step 20-80° C. or less by controlled addition of addition of hydrocarbon or heterocarbon compound.
12. The method of claim 1 , comprising maintaining temperature of the reaction second step at 110° C. or less.
13. The method of claim 1 , comprising maintaining temperature of the reaction second step at 80-100° C. or less by controlled addition of monohydridosiloxane.
14. The method of claim 1 , comprising maintaining temperature of the reaction second step by a staged addition of hydrocarbon or heterocarbon compound.