FLUO 34-Synthesis of low Ostwald coefficient perfluorinated ethers by the exploit of perfluoroalkyl hypofluorites.

Author(s): Navarrini, Walter; Venturini, Francesco; Sansotera, Maurizio; Metrangolo, Pierangelo; Resnati, Giuseppe; Galimberti, Marco; Tortelli, Vito.

Source: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY

Volume: 236

Meeting Abstract: 34-FLUO Published: AUG 17 2008

ABSTRACT:

The addiction reaction of hypofluorite to halogenated olefins has been studied in the past. In our previous studies we have noticed that the concentration of hypofluorite in the reaction media is an important variable to control the course of the main reaction. This experimental approach allowed the identification of a straight and economical methodology for the preparation of highly pure perfluoroethers with low boiling point and low Ostwald coefficient. These perfluoroethers have been recently tested as fluids for the preparation of injectable microbubble compositions as contrast agents in diagnostic ultrasound imaging. In many ultrasounds imaging applications there is the need for more efficient contrast agents and efforts to develop suitable materials are ongoing.

Addition of perfluoroolefins to trifluoromethyl hypofluorite for the preparation of low molecular weight perfluorinated oxygen containing fluids kinetics and byproducts.

Author(s): VENTURINI F., METRANGOLO P., RESNATI G., NAVARRINI W., TORTELLI V.

Source: Chimica Oggi – Chemistry Today.

Volume: 26 Pages: 36-38. Published: Aug. (2008).

ABSTRACT:

The products deriving from the addition of CF2=CFOCF3 to CF3OF are proved to be low Ostwald coefficient fluids suitable for producing high stable micro bubbles that can be used as ultrasound imaging contrast agents. The standard gas-liquid fast radical chain reaction between trifluoromethyl hypofluorite CF3OF and reactive perfluoroolefins like CF2=CFOCF3produces oligomerization and dimerization byproducts. Therefore a purification procedure is needed in order to separate the low Ostwald coefficient products from the reaction mixture. Surprisingly we have found that the selectivity of the reaction can be increased by modifying the experimental reaction conditions adopted. This behaviour is an experimental evidence for the presence of two different reaction schemes that can be switched by tuning the hypofluorite concentration in the reaction media.

The use of perfluoroalkyl hypofluorites for an efficient synthesis of perfluorinated ethers characterized by low Ostwald coefficient.

Author(s): NAVARRINI W., VENTURINI F., SANSOTERA M., URSINI M., METRANGOLO P., RESNATI G., GALIMBERTI M., BARCHIESI E., DARDANI P.

Source: Journal of Fluorine Chemistry.

Volume: 129 Issue: 8 Pages: 680-685.

DOI: 10.1016/j.jfluchem.2008.05.018. Published: Aug. (2008).

ABSTRACT:

In the reaction between perfluoroolefins and perfluoroalkylhypofluorites the existence of two different free radical reaction mechanisms is demonstrated by the presence of characteristic byproducts. These kinetic schemes can be experimentally controlled by tuning the hypofluorite concentration in the reaction media. In particular, in the reactions between trifluoromethyl hypofluorite and highly reactive perfluoroolefins like CF2CFOCF3 and CF2CF2, the free radical oligomerization and dimerization products can be suppressed by utilizing the opportune experimental conditions. The pure perfluorinated ethers obtained, having low Ostwald coefficient, can be utilized as contrast agents for diagnostic ultrasound imaging injectable microbubbles composition.

http://www.sciencedirect.com/science/article/pii/S0022113908001486

Propylene carbonate uptake and conductivity of lithiated short side chain perfluorinated sulfonic ionomeric membranes

Author(s): Navarrini, Walter; Scrosati, Bruno; Panero, Stefania; Sanguineti, Aldo; Alessandro, Ghielmi; Paolo, Fossati.

Source: CHIMICA OGGI-CHEMISTRY TODAY

Volume: 26 Issue: 3 Supplement: 1 Pages: 22-25 Published: MAY-JUN 2008

ABSTRACT:

Short Side Chain (SSC) ion-conducting polymers have revealed a better electrochemical behaviour compared to the long-side-chain (LSC) NAFION (R)-like polymers in the Polymer Electrolyte Membrane Fuel Cell (PEMFC) application (1). The relevance of the lithium form of HYFLON (R) ION as polymer electrolyte for lithium ion batteries has also been investigated. Starting from these SSC ionomers and utilising a particularly straightforward methodology for the preparation and dehydration of the lithium ion membrane in nonaqueous media, it has been possible to achieve a high ionic conductivity in the range of 10-3 S/cm at room temperature(2). The high concentration of lithium ions and the high polymer swelling in propylene carbonate solvent are not sufficient to explain the high ionic conductivity observed.

Lithiated short side chain perfluorinated sulfonic ionomeric membranes: Water content and conductivity

Author(s): Navarrini, Walter; Scrosati, Bruno; Panero, Stefania; Ghielmi, Alessandro; SSanguineti, Aldo); Geniram, Giuliana.

Source: JOURNAL OF POWER SOURCES

Volume: 178 Issue: 2 Pages: 783-788

DOI: 10.1016/j.jpowsour.2007.09.110 Published: APR 1 2008

ABSTRACT:

In view of possible applications as single-ion electrolyte for lithium batteries, some aspects of the lithium form of Hyflon Ion ionomer, a sulfonic short side chain (SSC) electrolyte, have been investigated. The synthesis of the ionomer and the successive membrane preparation is reported. An appropriate methodology for the direct salification of the ionomeric membrane from the SO2F form to lithium salt, using lithium hydroxide in absence of organic solvent has been found. Utilizing these SSC lithium ionomer membranes and though a particular methodology for the dehydration of the lithium ion membrane in non-aqueous media, it has been possible to achieve an ionic conductivity of 10(-3) S cm(-1) at room temperature [W. Navarrini, S. Panero, B. Scrosati, A. Sanguineti, European Patent 1,403,958 A1 (2003)]. Surprisingly it was observed that the membrane ionic conductivity depends on the dehydration methodologies adopted.

http://www.sciencedirect.com/science/article/pii/S0378775307021775

“Little barrel, good wine?”

Author(s): Navarrini, Walter

Source: CHIMICA OGGI-CHEMISTRY TODAY

Volume: 26 Issue: 1 Pages: 2-2 Published: JAN-FEB 2008