Synthesis
The hydrosilylation of siloxanes was carried out in a Pyrex temperature-controlled reactor. The catalyst was added to the reactor. A pre-prepared mixture of octamethylcyclotetrasiloxane, hydrogen, and vinylsiloxane was added in a 2:3:1 ratio. The reactor was evacuated and the mixture was kept at a constant temperature with stirring. Platinum was concentrated in C(4.2–17.0) × 10⁻⁵ mol g⁻¹ polymethyl sulfide. The mixture was heated at 70°C for 1.5 hours. The title compound, 1,1,3,3-tetramethyldisiloxane, was purified by silica gel column chromatography.
Figure 1, Synthetic route of 1,3,3-tetramethyldisiloxane
Description
1,1,3,3-Tetramethyldisiloxane is soluble in many organic solvents, such as aromatic hydrocarbon and petroleum hydrocarbons, and so on. This product is a kind of widely used organic silicon intermediates, and usually be used as organic silicon blocking agent. Due to containing reactive Si-H groups in the molecular structure, it can be used in the synthesis of copolymer macromolecule by hydrosilylation. The synthesis of copolymer macromolecule can be made into a series of reactive silicone oil.
Chemical Properties
Colorless or yellowish transparent liquid
Uses
1. Synthesis of polysiloxane containing faculties end groups.
2. Can be used for the preparation of high performance organic silicone surfactants.
3. Applicable to the production of many products, such as addition silicon rubber, silica gel, Hydrogenpolysiloxane and plastic, resin modifier, dendrite polymer special additives, etc.
Uses
1,1,3,3-Tetramethyldisiloxane is used as a monomer in the production of silicone polymers or silicone resins. It is used as a precursor to prepare other organosilicon compounds. It is also utilized in non-aqueous polymer preparation as well as a laboratory reagent.
Application
1, 1, 3, 3-Tetramethyldisiloxane is a kind of siloxane derivative, and can be used as a monomer for the preparation of silicone polymers or silicone resins. It is used as an intermediate for preparing other organosilicon compounds. It is also used in non-aqueous polymer preparation as well as a laboratory reagent. In organic synthesis, it finds an application as an effective reducing agent in platinum-catalyzed reduction of carboxamides to amines as well as in the Au/TiO2-catalyzed hydrosilylation of carbonyl compounds (e.g., reduction of aldehydes or ketones) relative to monohydrosilanes. It can also enable a direct bromination of carboxylic acids in the presence of indium bromide (InBr3) as catalyst.
Flammability and Explosibility
Highly flammable
reaction suitability
reagent type: reductant
Purification Methods
1,Possible impurity is 1,1,5,5-tetramethyl-3-trimethylsiloxytrisiloxane b 154-155o/733mm. Fractionate it, collect fractions boiling below 80o and re-fractionate it. Its purity can be analysed by alkaline hydrolysis and measuring the volume of H2 liberated followed by gravimetric estimation of silica in the hydrolysate. It is unchanged when stored in glass containers in the absence of moisture for 2-3 weeks. Small amounts of H2 are liberated on long storage. Care should be taken when opening a container due to pressure developed. [Speier et al. J Am Chem Soc 79 974 1958, Emeléus & Smythe J Chem Soc 609 1958, IR: Kriegsmann Z Anorg Chem 299 78 1959, Beilstein 4 IV 3991.]
Toxicity evaluation
1,1,3,3-Tetramethyldisiloxane is irritating to the eyes and upper respiratory tract. Ingestion can be fatal.
Toxics Screening Level
The ITSL for tetramethyldihydrogendisiloxane is being established at this time as 120 μg/m3 with annual averaging.
References
https://www.alfa.com/en/catalog/B23697/
http://www.organic-chemistry.org/chemicals/reductions/tetramethyldisiloxane-TMDSO.shtm
https://www.infona.pl/resource/bwmeta1.element.elsevier-722236cc-df38-37aa-bbed-029ec07d525f
