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When Attempting Chain Extension, Even Without Solvent, It Is Not Possible to Avoid Chojnowski Metathesis Giving D3

Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street, W. Hamilton, ON L8S 4M1, Canada
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Academic Editors: Sławomir Rubinsztajn, Marek Cypry and Wlodzimierz Stanczyk
Molecules 2021, 26(1), 231; https://doi.org/10.3390/molecules26010231
Received: 11 December 2020 / Revised: 29 December 2020 / Accepted: 31 December 2020 / Published: 5 January 2021
A simple, mild and efficient method to prepare HSi- or HOSi-telechelic, high-molecular-weight polydimethylsiloxane polymers (to 41,600 g·mol−1) using the one-shot hydrolysis of MHMH is reported; titration of the water allowed for higher molecular weights (to 153,900 g·mol−1). The “living” character of the chain extension processes was demonstrated by adding a small portion of MHMH and B(C6F5)3 (BCF) to a first formed polymer, which led to a ~2-fold, second growth in molecular weight. The heterogeneous reaction reached completion in less than 30 min, much less in some cases, regardless of whether it was performed neat or 50 wt% in dry toluene; homogeneous reactions in toluene were much slower. The process does not involve traditional redistribution, as judged by the low quantities (<3%) of D4 produced. However, it is not possible to avoid Chojnowski metathesis from MHDDMH giving D3, which occurs competitively with chain extension. View Full-Text
Keywords: silicone polymers; Piers–Chojnowski–Rubinsztajn–Kawakami reaction; chain extension by Si-H hydrolysis; siloxane metathesis; D3 synthesis silicone polymers; Piers–Chojnowski–Rubinsztajn–Kawakami reaction; chain extension by Si-H hydrolysis; siloxane metathesis; D3 synthesis
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MDPI and ACS Style

Liao, M.; Chen, Y.; Brook, M.A. When Attempting Chain Extension, Even Without Solvent, It Is Not Possible to Avoid Chojnowski Metathesis Giving D3. Molecules 2021, 26, 231. https://doi.org/10.3390/molecules26010231

AMA Style

Liao M, Chen Y, Brook MA. When Attempting Chain Extension, Even Without Solvent, It Is Not Possible to Avoid Chojnowski Metathesis Giving D3. Molecules. 2021; 26(1):231. https://doi.org/10.3390/molecules26010231

Chicago/Turabian Style

Liao, Mengchen; Chen, Yang; Brook, Michael A. 2021. "When Attempting Chain Extension, Even Without Solvent, It Is Not Possible to Avoid Chojnowski Metathesis Giving D3" Molecules 26, no. 1: 231. https://doi.org/10.3390/molecules26010231

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