Date of Award
August 2016
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
School of Materials Science and Engineering
Committee Member
Joseph S Thrasher
Committee Member
Marek W Urban
Committee Member
Gary C Lickfield
Committee Member
Stephen H Foulger
Abstract
The main focus of this work is the synthesis of hydrofluorocarbon ethers (HFEs). New synthetic methods and new HFEs were successfully developed. In Chapter 1, new HFEs were synthesized with tetrafluoroethylene (CF2=CF2, TFE) as new engineered fluids. The fluorinated olefins’ addition to alcohols is a more conventional approach to HFEs, and in our group a synthetic method consists of three steps was attempted:
a. radical addition of tetrafluoroethylene (TFE) to 2,2-dimethyl-1,3-dioxolane compound; b. hydrolysis of the fluorinated dioxolane compound to make a diol; c. TFE addition to the diol under ionic condition.
The following two chapters cover the synthesis of several other HFEs with a strong Lewis acid. Especially the one-step synthesis of sevoflurane starting from hexafluoroisopropanol (HFIP) and difluoromethane (R32) with SbF5 as catalyst gives 95+% yield which is very attractive to industry, meanwhile the catalysts can be recycled for multiple reactions. Several other existing or new HFEs were also synthesized by using the same method. The products were identified with NMR spectroscopy and gas chromatography/mass spectrometry.
Another cyclic hydrofluorocarbon ether compound 2,2,5,5-tetrafluoro-2,5-dihydrofuran (M1) was synthesized as a monomer for the development of new amorphous fluoropolymers. M1 has been successfully copolymerized with several perfluoro olefins including CF2=CF2 (TFE), CF3CF=CF2 (HFP), and SF5CF=CF2 (MSF5). And the materials were characterized and analyzed by NMR spectroscopy, attenuated total reflectance-infrared spectroscopy (ATR-IR), thermalgravimetric analysis/mass spectrometry (TGA/MS), scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX), gel permeation chromatography (GPC) and static light scattering (SLS).
Along the work of the polymerization of M1, more chemistry has been explored on M1 and several crystal structures were solved, which will be further discussed in Chapter 5 and Chapter 6. In the crystal structures, a variety of short distance contacts of Ag---Ag, Ag---O, H---F, O---F, O-Cl, and F---F, were observed. Two other bissulfonyl chloride compounds were synthesized and in the structure of these two -SO2Cl containing molecules, Cl---O and F---F short contacts were observed and considered as halogen bonding.
Recommended Citation
Liu, Xiaolin, "Synthesis of Hydrofluorocarbon Ethers and New Amorphous Fluoropolymers with Cyclic Fluorocarbon Ether Units" (2016). All Dissertations. 2539.
https://tigerprints.clemson.edu/all_dissertations/2539