Tetramethyldisiloxane

Bu3P-Pt(0) complex was prepared by the literature procedure 2 FBu3P (32 mg, 0.158 mmol) (Strem Chemicals) was dissolved in platinum(0)-l,3-divinyl-l,l,3,3-tetramethyldisiloxane complex (1.5 mL of xylene solution obtained from Aldrich Chemical Company, Inc., catalog number 47-951-9). The mixture was stirred at 65°C (oil bath) for 5 min and then was slowly cooled to room temperature. This solution could be stored under N2 in the freezer indefinitely. 

The hydrosilylation of 1-heptyne with 1,1,3,3-tetramethyldisiloxane is exothermic. If the temperature of the reaction exceeds 30°C, the amount of the undesired a-isomer will increase. However, the solution should not be cooled to below 10°C as the reaction becomes very sluggish. 

Synthesis ofa,[Pg.13]

During the synthesis of functional disiloxanes via hydrosilation, the starting materials are usually either tetramethyldisiloxane or dimethylchlorosilane and a proper olefinic (mostly allyl type) compound having the desired functional end group. If dimethylchlorosilane is employed, the hydrosilation is usually followed by hydrolysis. As a specific example, the synt hesis of 1,3-bis(3-glycidoxypropyl)tetramethyldisiloxane is shown in Reaction Scheme IV. 

The a,oo-difunctional PDMS is obtained by cationic polymerization of octamethyl-cyclotetrasiloxane (D4) in the presence of a known amount of tetramethyldisiloxane, acting as a functional transfer agent. Hydrosilylation reaction is carried out in toluene solution at 90 °C with a platinum catalyst. 

It should be remarked here that trimethylsilane 84 a or triethylsilane 84 b and most other known silanes, for example tetramethyldisiloxane 1788, are quite expensive for any large-scale reduction, whereas the subsequently described poly-methylhydrosiloxane 1856 (cf. reductions of an azide moiety in 1855 and a carbo-benzoxy moiety in 1859) is available as large-scale orders for ca 15 kg , which is only a fraction of the cost of any other silane. 

Oxygen, Sodium hydroxide, Water See Oxygen (Gas) Tetramethyldisiloxane See related ALKYLSILANES... 

Dienes bonded to silicones to give products stable to hydrolysis are available in a wide variety of combinations, from the distillable l,3-bis(isoprenyl)-l,l,3,3-tetramethyldisiloxane to high polymers with dozens of diene groups attached [23], Diels-Alder cycloadditions may be performed with dieno-philes. Maleic anhydride adds almost quantitatively to the conjugated diene system, giving easy access to a siloxane species of considerable industrial importance [24]. 

The use of trimethylsilyl-based electrophilic catalysts with organosilicon hydrides also promotes the conversion of aldehydes into ethers and avoids the need to employ the potentially hazardous trityl perchlorate salt.314,334,338 One reagent pair that is particularly effective in the reductive conversion of aldehydes into symmetrical ethers is a catalytic amount of trimethylsilyl triflate combined with either trimethylsilane, triethylsilane, PMHS,334 or 1,1,3,3-tetramethyldisiloxane (TMDO, 64) as the reducing agent (Eq. 179).314 Either... 

Di-w -pentyl Ether [TMSI-Catalyzed Reduction of an Aldehyde to a Symmetrical Ether].314 A mixture of sodium iodide (0.15 g, 1 mmol), 1-pentanal (1.06 mL, 10 mmol), and trimethylsilyl chloride (2.0 mL, 15.4 mmol) was stirred in MeCN (5.0 mL) at room temperature for 10 minutes, after which 1,1,3,3-tetramethyldisiloxane (TMDO, 1.79 mL, 10 mmol) was added. When the exothermic reaction had ended (30 minutes), a solution of 2.5 N HF in MeOH (30 mL) was added to the reaction mixture, which was then refluxed for 5 minutes. Work-up was carried out by diluting the solution with CH2CI2 (40 mL), washing with water (30 mL) and saturated aqueous NaHC03 solution (20 mL), drying, and evaporating the solvents. Crude di-n-pentyl ether was purified by distillation 0.65 g (84%) bp 185-1897760 Torr. 

Tetramethyldisiloxane (TMDS) is a very convenient reagent to prepare HGeX3 (where X = F, Cl, Br, I), as adducts, from tetrahalogermanes214 ... 

Synthesis methods a, -oligodihydridedimethylsiloxanes were synthesized by the methods described in ref [11]. 1,3-tetramethyldisiloxane was obtained by hydrolysis of dimethylchlorinesilane [10], 1,5-trimethyltriphenyltrisiloxane has been synthesized by reduction of 1,5-dichlorine-1,3,5-trimethyltriphenyltrisiloxane with LiAlH4 [10], 1,5-tetra-methyl-3,3-diphenyltrisiloxane was obtained via interaction of (Me)2SiHCl with diphenyl-silandiol [7],... 

Octamethyltetrasiloxane (D ) and octaphenyltetrasiloxane (D ") were generously supplied by General Electric Co., Silicone Products Division. l,3-Bis(4-hydroxybutyl)tetramethyldisiloxane and l,3-Bis(y-aminopropyl)tetramethyldisiloxane were purchased from Sllar Laboratories and Petrarch respectively. Trifluoroacetic acid was a product of Aldrich. All other chemicals were reagent grade and used without further purification. 

Depending on the desired levels of diphenylsiloxane units and the molecular weight of the final product, calculated amounts of D, D and 1,3-bis(y-aminopropyl)tetramethyldisiloxane were introduced into a round bottom, 3-necked flask fitted with a condenser, thermometer and argon inlet. Later 0.01-0.1% by weight of finely ground... 

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