Synthesis of perfluorinated ethers by solution phase direct fluorination: an adaptation of the La-Mar technique

Abstract

The synthesis of several perflourinated ethers of pentaerythritol, dipentaerythritol, and tripentaerythritol by direct fluorination in solution is described. These ethers were perfluorinated using elemental fluorine in a two step process. In the first step, up to 95 percent of the hydrogens were replaced by fluorine while the ether was dissolved in a chlorofluorocarbon slolvent. The remaining hydrogens were replaced by exposing the partially fluorinated product to pure fluorine at elevated temperature. The hydrocarbon ethers used as starting material were prepared by applying the use of phase transfer catalysis to the Williamson ether synthesis. Six of the perfluorinated ethers prepared have been previously synthesized by other methods: perfluoro-5, 5-bis (ethoxymethyl)-3, 7-dioxanonane, perfluoro-6, 6-bis(propyloxymethyl)-4, 8-dioxaundecane, perfluoro-7, 7-bis(butyloxymethyl)-5, 9-dioxatridecane, perfluoro-8, 9-bis(pentyloxymethyl)-6, 10-dioxapentadecane, perfluoro-7, 7-bis(2-methoxyethoxymethyl)-2, 5, 9, 12-tetraoxatridecane, and perfluoro-4, 4, 8, 8-tetrakis (methoxymethyl)-2, 6, 10-trioxaundecane. In addition, the following compounds were isolated and characterized: Perfluoro-2, 12-dimethyl-7, 7-bis (2-methylbutyloxymethyl)-5, 9-dioxatridecane, perfluoro-9, 9-bis (hexyloxymethyl)-7, 11-dioxaheptadecane, perfluoro-10, 10-bis (heptyloxymethyl)-8, 12-dioxanonadecane, perfluoro-11, 11-bis(octyloxymethyl)-9, 13-dioxaheneicosane, perfluoro-5, 5, 9, 9-tetrakis (ethoxymethyl)-3, 7, 11-trioxatridecane, perfluoro-6, 6, 10, 10,-tetrakis (propyloxymethyl)-4, 8, 12-trioxapentadecane, perfluoro-7, 7, 11, 11-tetrakis (butyloxymethyl) -5, 9, 13-trioxaheptadecane, perfluoro-7, 7, 11, 11-tetrakis (2-methoxyethoxymethyl)-2, 5, 9, 13, 16-pentaoxaheptadecane, perfluoro-4, 4, 8, 8, 12, 12-hexakis (methoxymethyl )-2, 6, 10, 14-tetraoxapentadecane and perfluoro-5, 5, 9, 9, 13, 13-hexakis (ethoxymethyl)-3, 7, 11, 15-tetraoxaheptadecane