Polysulfates and polysulfonates possess exceptional mechanical properties making them potentially valuable engineering polymers. However, they have been little explored due to a lack of reliable synthetic access. Here we report bifluoride salts (Q+[FHF]–, where Q+ represents a wide range of cations) as powerful catalysts for the sulfur(VI) fluoride exchange (SuFEx) reaction between aryl silyl ethers and aryl fluorosulfates (or alkyl sulfonyl fluorides). The bifluoride salts are significantly more active in catalysing the SuFEx reaction compared to organosuperbases, therefore enabling much lower catalyst-loading (down to 0.05 mol%). Using this chemistry, we are able to prepare polysulfates and polysulfonates with high molecular weight, narrow polydispersity and excellent functional group tolerance. The process is practical with regard to the reduced cost of catalyst, polymer purification and by-product recycling. We have also observed that the process is not sensitive to scale-up, which is essential for its future translation from laboratory research to industrial applications.
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Financial support was provided by the National Science Foundation (CHE-1610987 to K.B.S.) and the National Institutes of Health (GM093282 to P.W.). Part of the work was carried out as a user project at the Molecular Foundry, which was supported by the Office of Science, Office of Basic Energy Sciences, of the US Department of Energy under contract no. DE-AC02-05CH11231. B.G. is grateful for the postdoctoral fellowship support from the Shanghai Institute of Organic Chemistry (SIOC), Chinese Academy of Science (CAS), Pharmaron and Zhejiang Medicine. J.D. is grateful for the One Hundred Talents Program supported by SIOC, CAS. J.D. is financially supported by the Strategic Priority Research Program of the CAS (XDB200203) and the National Natural Science Foundation of China (21672240). We thank P. Dawson at The Scripps Research Institute (TSRI) for the anhydrous HF experiment. We also thank S. Li and C. J. Hawker at University of California, Santa Barbara, Q. Xu and B. Wu at Soochow University, S. Li and H. Wang at TSRI for helpful discussions on this project.
A patent application covering this work has been filed by TSRI (US patent application no. 62/182755, International patent application no. PCT/US2016/038701).
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Gao, B., Zhang, L., Zheng, Q. et al. Bifluoride-catalysed sulfur(VI) fluoride exchange reaction for the synthesis of polysulfates and polysulfonates. Nature Chem 9, 1083–1088 (2017). https://doi.org/10.1038/nchem.2796
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