540-97-6Relevant articles and documents
Synthesis of 14C-labeled cyclic and linear siloxanes
Varaprath, Sudarsanan
, p. 37 - 47 (1999)
Simple procedures to synthesize a variety of 14C-labeled monomeric and polymeric siloxanes are described. Specifically, the synthesis of the following siloxanes, some of which are of significant commercial importance are provided: 14C-octamethylcyclotetrasiloxane (D4), 14C-decamethylcyclopentasiloxane (D5), 14C-hexamethyldisiloxane (MM), 14C-dimethyldimethoxysilane and 14C-dimethylsilanediol (DMSD) are examples of discrete monomeric species. 14C-350 and 1000 cSt polydimethylsiloxanes (PDMS) are examples of polymeric species. Synthesis of the monomeric species with the exception of dimethylsilanediol involve reactions of Grignard reagents with the appropriate chlorosilanes, while the polymeric materials were synthesized via acid catalyzed equilibration reaction of 14C-D4 with dodecamethylpentasiloxane (MD3M). The compound 14C-DMSD was obtained by the hydrolysis of 14C-dimethyldimethoxysilane. The labeled materials listed here were synthesized for their utility as tracers in several of the ongoing environmental fate and effects studies as well as toxicological investigations.
Razumovskii et al.
, (1975)
High-efficiency macrocyclic dimethyl siloxane compound preparation method
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Paragraph 0008; 0015, (2017/10/13)
The invention discloses a high-efficiency macrocyclic dimethyl siloxane compound preparation method which comprises the following steps: (1) utilizing tetramethyl disiloxane and octamethyl cyclotetrasiloxane as raw materials, performing ring-openingopen cycle in a sodium hydroxide or potassium hydroxide water solution and then inserting again to obtain dimethyl hydrogen silicone end capped direct-linked siloxane; (2) chlorinating the dimethyl hydrogen silicone end capped direct-linked siloxane with acetyl chloride under a catalytic effect of aluminum trichloride to obtain dimethyl chlorosilane end capped direct-linked siloxane; (3) hydrolyzing the direct-linked siloxane under the alkali condition to obtain varieties of macrocyclic diemthyl silicon ring bodies. The preparation method has simple steps and economical and safe technology and can be used for obtaining varieties of high-purity macrocyclic diemthyl silicon ring body products from simple raw materials; thus, high-difficulty distillation is avoided, and the preparation method is very suitable for industrial production.
One-Step Synthesis of Siloxanes from the Direct Process Disilane Residue
Neumeyer, Felix,Auner, Norbert
supporting information, p. 17165 - 17168 (2016/11/23)
The well-established Müller–Rochow Direct Process for the chloromethylsilane synthesis produces a disilane residue (DPR) consisting of compounds MenSi2Cl6?n(n=1–6) in thousands of tons annually. Technologically, much effort is made to retransfer the disilanes into monosilanes suitable for introduction into the siloxane production chain for increase in economic value. Here, we report on a single step reaction to directly form cyclic, linear, and cage-like siloxanes upon treatment of the DPR with a 5 m HCl in Et2O solution at about 120 °C for 60 h. For simplification of the Si?Si bond cleavage and aiming on product selectivity the grade of methylation at the silicon backbone is increased to n≥4. Moreover, the HCl/Et2O reagent is also suitable to produce siloxanes from the corresponding monosilanes under comparable conditions.
