High molecular weight cyclic polysiloxanes from organocatalytic zwitterionic polymerization of constrained spirocyclosiloxanes

Wu, Chunyan; Yu, Jianyi; Li, Qiaosheng; Liu, Yuzhou

doi:10.1039/c7py01499f

Cited by 23 publications

(18 citation statements)

References 38 publications

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“…Only a single compound resulted (MW ≈2600 g mol −1 , Figure C) in excellent yield, in a process that can be readily scaled up. In an interesting recent example of structural control in the synthesis of large silicones, the highly strained monomer QD 4 could be prepared by a PR process, and then ring expanded into polycyclic structures (Figure ) …”

Section: Piers–rubinsztajn (Pr) Reactionmentioning

confidence: 99%

“…In an interesting recent example of structural control in the synthesis of large silicones, the highly strained monomer QD 4 could be prepared by aP Rp rocess, and then ring expanded into polycyclics tructures ( Figure 13). [56] Branched structures impart very different properties to polymers than their linear analogues.H owever,a lmost no studies have been undertaken of branched silicones because of the paucityo fm ethods for their synthesis. The one key publication in this area created branched polymers by radicalg rafting, but admitted that the processes used led to crude mixtures, including ag el fraction.…”

Section: Organofunctional Linear Siliconesmentioning

confidence: 99%

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New Control Over Silicone Synthesis using SiH Chemistry: The Piers–Rubinsztajn Reaction

Brook

2018

Chemistry A European J

104

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There is a strong imperative to synthesize polymers with highly controlled structures and narrow property ranges. Silicone polymers do not lend themselves to this paradigm because acids or bases lead to siloxane equilibration and loss of structure. By contrast, elegant levels of control are possible when using the Piers-Rubinsztajn reaction and analogues, in which the hydrophobic, strong Lewis acid B(C F ) activates SiH groups, permitting the synthesis of precise siloxanes under mild conditions in high yield; siloxane decomposition processes are slow under these conditions. A broad range of oxygen nucleophiles including alkoxysilanes, silanols, phenols, and aryl alkyl ethers participate in the reaction to create elastomers, foams and green composites, for example, derived from lignin. In addition, the process permits the synthesis of monofunctional dendrons that can be assembled into larger entities including highly branched silicones and dendrimers either using the Piers-Rubinsztajn process alone, or in combination with hydrosilylation or other orthogonal reactions.

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Section: Piers–rubinsztajn (Pr) Reactionmentioning

confidence: 99%

Section: Organofunctional Linear Siliconesmentioning

confidence: 99%

New Control Over Silicone Synthesis using SiH Chemistry: The Piers–Rubinsztajn Reaction

Brook

2018

Chemistry A European J

104

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“…Therefore, the cyclic polymers in the field of silicone materials should be an unmissable topic for researchers. Liu et al [31] initially attempted to synthesize a small molecule with a bicyclic ring under BCF catalysis using 1,1,2,2-tetramethyldisiloxane and tetraethoxysilane, as shown in Figure 5.…”

Section: Morphology-controlled Synthesis Of Polysiloxanes Via the mentioning

confidence: 99%

“…Synthesis of small molecule cyclic siloxane by the PR reaction [31]. Reproduced with the copyright permission.…”

Section: Figurementioning

confidence: 99%

Synthesis of Structurally Precise Polysiloxanes via the Piers–Rubinsztajn Reaction

Chen

et al. 2019

Materials

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Silicone materials are widely used, from daily life to the military industry. With the advancement of science and technology and the increasing demands of industry, the requirement for high-performance precise structural silicone materials has increased. Therefore, the most important aspect in this field is finding a breakthrough in the synthetic methods. In this review, the latest research developments in controllable morphological structure and composite structure optimized synthesis of silicone materials using the Piers–Rubinsztajn (PR) reaction are summarized. The advantages of the PR reaction compared with traditional synthetic routes to silicone materials are presented. The highly controllable spatial structure of silicone materials and the structural combination of biomass or inorganic materials with silicone materials results in an improvement in performance or function. The morphological control of more complex silicone materials and the synthesis of non-traditional silicone materials with composite structures through the PR reaction will be the main research directions for the development of silicone materials in the future.

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“…Main group (and metal-free) catalysts such as B(C 6 F 5 ) 3 have gained great interest as a catalyst activator and as strong Lewis acid for many purposes (Piers, 2004;Lawson and Melen, 2017;Brook, 2018). Several studies have been published for the preparation of siloxanes and hyperbranched siloxanes involving catalytic cross-coupling reactions of oxygen nucleophiles (e.g., alkoxysilanes, silanols, phenols, and ethers) with hydrosilanes (Kawakami et al, 2004;Chojnowski et al, 2005Chojnowski et al, , 2006Chojnowski et al, , 2008Zhou and Kawakami, 2005;Shinke et al, 2007;Thompson and Davies, 2007;Cella and Rubinsztajn, 2008;Kurjata et al, 2009;Feghali and Cantat, 2014;Madsen et al, 2014;Zhang et al, 2014Zhang et al, , 2020Feghali et al, 2015;Laengert et al, 2017;Szawiola et al, 2017;Wu et al, 2017;Brook, 2018;Ai et al, 2019). Recently, Matsumoto and co-workers reported a sequencecontrolled synthesis of oligosiloxanes via dehydrocarbonative coupling of alkoxysilanes and hydrosilanes, named the Piers-Rubinsztajn reaction, and also via hydrosilylation of carbonyl compounds using B(C 6 F 5 ) 3 (Matsumoto et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Catalytic Synthesis of Oligosiloxanes Mediated by an Air Stable Catalyst, (C6F5)3B(OH2)

et al. 2020

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The utility of (C 6 F 5) 3 B(OH 2) as catalyst for the simple and environmentally benign synthesis of oligosiloxanes directly from hydrosilanes, is reported. This protocol offers several advantages compared to other methods of synthesizing siloxanes, such as mild reaction conditions, low catalyst loading, and a short reaction time with high yields and purity. The considerable H 2 O-tolerance of (C 6 F 5) 3 B(OH 2) promoted a catalytic route to disiloxanes which showed >99% conversion of three tertiary silanes, Et 3 SiH, PhMe 2 SiH, and Ph 3 SiH. Preliminary data on the synthesis of unsymmetrical disiloxanes (Si-O-Si') suggests that by modifying the reaction conditions and/or using a 1:1 combination of silane to silanol the cross-product can be favored. Intramolecular reactions of disilyl compounds with catalytic (C 6 F 5) 3 B(OH 2) led to the formation of novel bridged siloxanes, containing a Si-O-Si linkage within a cyclic structure, as the major product. Moreover, the reaction conditions enabled recovery and recycling of the catalyst. The catalyst was re-used 5 times and demonstrated excellent conversion for each substrate at 1.0 mol% catalyst loading. This seemingly simple reaction has a rather complicated mechanism. With the hydrosilane (R 3 SiH) as the sole starting material, the fate of the reaction largely depends on the creation of silanol (R 3 SiOH) from R 3 SiH as these two undergo dehydrocoupling to yield a disiloxane product. Generation of the silanol is based on a modified Piers-Rubinsztajn reaction. Once the silanol has been produced, the mechanism involves a series of competitive reactions with multiple catalytically relevant species involving water, silane, and silanol interacting with the Lewis acid and the favored reaction cycle depends on the concentration of various species in solution.

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High molecular weight cyclic polysiloxanes from organocatalytic zwitterionic polymerization of constrained spirocyclosiloxanes

Abstract: A new cyclic polysiloxane molecule with high molecular weight was prepared through zwitterionic polymerization of constrained spirocyclosiloxanes.

Cited by 23 publications

References 38 publications

New Control Over Silicone Synthesis using SiH Chemistry: The Piers–Rubinsztajn Reaction

New Control Over Silicone Synthesis using SiH Chemistry: The Piers–Rubinsztajn Reaction

Synthesis of Structurally Precise Polysiloxanes via the Piers–Rubinsztajn Reaction

Catalytic Synthesis of Oligosiloxanes Mediated by an Air Stable Catalyst, (C6F5)3B(OH2)

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