Allen Capron Sievert

Synthesis of perfluorinated ethers by an improved solution phase direct fluorination process

Abstract We have developed schemes to make perfluorinated ethers that cover a wide range of molecular weights and boiling points. We describe a relationship that can be used to predict the boiling points of perfluoro polyethers; this is used to assist in the combination of reagents for synthesizing a target having particular physical properties such as boiling point, etc. Our first scheme is to build molecular weight by condensing polyols with fluoro-olefins such as TFE and HFP. These intermediates are then fluorinated by a simple solution phase, batch, photo-assisted direct fluorination to give high yields of isomerically pure perfluorinated ethers. In a second scheme we use ethylene oxide to fine-tune the molecular weight of the polyol, and the weight of these can be extended by reaction with an appropriate fluoro-olefin. These intermediates can be fluorinated using our batch fluorinator to make new perfluorinated ethers of a specific molecular weight and boiling point.

The chlorination of 1,2-difluoroethane (HFC-152)

Abstract The photochlorination of CH2FCH2F yields CH2FCC12F and CHClFCHClF, both of whichwere considered to be potential replacements for CFC-113 (CCI2FCF2Cl) based on theirboiling points (48 °C and 59 °C, respectively). The CHClFCHClF/CH2FCCl2F ratio canbe controlled by the choice of solvents. In aromatic solvents, the reactivity of the chlorineradical is reduced, increasing the amount of CH2FCCl2F produced. Relative rates in CCl4and in the presence of water were compared to rates in aromatic solvents. Both CH2FCCl2Fand CHClFCHClF failed in early toxicity tests and will thus not be pursued as HCFCreplacements for CFC-113.