Synthesis And Characterization Of Reactive Functional Group Siloxanes

The preparation of 1,3-bis(y-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane,1,3-divinyl-1,1,3,3-tetramethyl-disiloxane,1,3-bis(y-chloropropyl)-1,1,3,3-tetramethyldisilo-xane are studied in this paper. The main methods and results are as follows:1. Hydroxyl protection-hydrosilylation and alcoholysis-hydrosilylation methods are used to prepare 1,3-bis(y-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane were studied. By means of hydroxyl protection-hydrosilylation, four parts of tetraethoxysilane reacted with one part of allyl alcohol under the condition of sodium ethoxide, and the main product was triethoxyallyloxysilane(Ⅰ). Triethoxyallyloxysilane was purified by distillation, and then reacted with 1,1,3,3-tetramethyldisiloxane in the presence of Platinum compound, and 1,3-(y-triethoxysiliconoxypropyl)-1,1,3,3-tetramethyl-disiloxane(Ⅱ) was obtained two hours later. 1,3-bis(y-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane(BHTS) was received by homogeneous hydrolysis ofⅡin the mixed solvent of 2% sodium hydroxide solution and ethanol. With the total yield of 76.4% in terms of 1,1,3,3-tetramethyldisiloxane.By means of alcoholysis-hydrosilylation, it refers low-boiling residues(LBR) that derives from the production of methylcholorosilane monomers. LBR used in this paper contains dimethylchlorosilane (43.6%). LBR was reacted with allyl alcohol in the presence of urea, and dimethylallyloxysilane was received. Hydrosilylation was arised intermolecular and intramolecular of dimethylallyloxysilane in the presence of Pt complexes. Target product was obtained by hydrolysis of hydrosilation product in 10% HCl solution, with the yield of 51% in terms of allyl alcohol. Provide references for the preparation of BHTS.2. 1,3-divinyl-1,1,3,3-tetramethyldisiloxane(VMM) was prepared in the presence of RhCl3/i-PrOH, by means of bubble and constant volume. Acetylene was introduced into Rh complexes contained 1,1,3,3-tetramethyldisiloxane by bubble,35-50℃is identified to be the appropriate temperature. Small scale water introduced in the reaction system, and acetylene directly used have little effects to hydrosilation. And the catalyst was still active after the fourth usage, but the yield reduced by 1/4. While by means of constant volume, it can avoid the loss of 1,1,3,3-tetramethyldisiloxane as in the means of bubble, with the yield of 98% in terms of 1,1,3,3-tetramethyldisiloxane.It can raise the usage of rude material,and provide reference method for the industrial preparation of VMM.3. The relative high dimethylchlorosilane contained LBR hydrosilation with allylchloride in the presence of Pt complexes, and y-chloropropyldimethylchlorosilane was obtained, yields 45.6%. 1,3-bis(y-chloropropyl)-1,1,3,3-tetramethyldisiloxane was received by the hydrolysis of y-chloropropyldimethylchlorosilane, single step yields 95%. It provides reference method for the reuse of LBR.The originality in this thesis:(1) Tetraethoxysilane was used as hydroxyl protective agent. The hydroxyl in allyl alcohol was blocked in the presence of sodium ethoxide in order to prepare triethoxyallyloxysilane(Ⅰ).1,3-bis(y-triethoxysiliconoxypropyl)-1,1,3,3-tetramethyl-disiloxane(Ⅱ) was prepared through hydrosilylation of 1,1,3,3-tetramethyldisiloxane with triethoxyallyloxysilane. And 1,3-bis(y-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane was obtained by hydrolysis of II in the mixed solvent of 2% sodium hydroxide solution and ethanol. There are some advantages:tetraethoxysilane is not expensive, the requirement for this reaction is low and yields good. We provide a method to protect hydroxyl and prepare 1,3-bis(y-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane.(2) It's difficult to purify dimethylchlorosilane from LBR, so we directly used LBR, reacted with allyl alcohol and allyl chloride successfully, 1,3-bis(y-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane and 3-chloropropyldimethyl chlorosilane were prepared. It offers references to the reuse of LBR.