Giuseppe Marchionni

Computational studies of the reaction of the hydroxyl radical with hydrofluorocarbons (HFCs) and hydrofluoroethers (HFEs)

Abstract The reaction rate constants of a hydroxyl radical with some hydrofluorocarbons and hydrofluoroethers have been calculated using “transition state theory”. A new computational method has been developed for transferring along the reaction coordinate the very high accuracy corrections, obtained at G2 level of theory, from small models (CH 4 and CF 3 H) to larger molecules (halogenated ethanes and methyl ethers). The substituent effects on the CH bond strengths and on the reaction rate constants have been examined, as well as the geometrical and electronic features of the transition states.

Hydrofluoropolyethers: a new “friendly” generation of fluorinated fluids

Abstract In this paper, some physico-chemical properties of a novel class of α–ω hydrofluoropolyethers (HFPEs) having terminal hydrogen atoms are presented and compared with those of similar perfluorinated structures. The effect of –CF 2 H end groups has been studied for the lower members of this family and its group contributions, determined for some physico-chemical properties, have been calculated and can be used to predict properties of new structures.

Photochemical fluorination of perfluoropolyether functional derivatives

Abstract Oligomeric perfluorinated polyethers bearing various carbonylic end groups are reacted, at low or moderate temperatures, with fluorine under the influence of UV light. Carboxylic acylfluoride, and trifluoromethylketone groups are quantitatively cleaved under these conditions, while fluoroformate groups are mainly transformed into stable fluoroxy derivatives. Some mechanistic aspects of these photoreactions are discussed.

Vibrational spectra and quantum chemical calculations of some polyfluoroethers

Abstract Vibrational spectroscopy and Density Functional Theory (DFT) quantum chemical calculations, have been used to investigate structure and chemical properties of some fluorinated ethers. A good agreement between experimental and theoretical results has been obtained. Interesting conformational behaviour has been observed and interpreted for C-H bonds in difluoromethyl end groups. These effects help in understanding the chemical behaviour of these compounds, since C-H equilibrium bond length and bond dissociation energy (BDE) can be correlated with Vibrational properties.

Perfluoro Allyl Fluorosulfate (FAFS): A Versatile Building Block for New Fluoroallylic Compounds

In this study we will present and discuss both the synthesis of CF2=CFCF2OSO2F (perfluoroallyl fluorosulfate, FAFS), focusing in particular on the important role of C3F6/SO3 ratio, reaction temperature and boron catalyst/SO3 ratio on FAFS’ yield and selectivity, as well as a wide variety of ionic and radical reactions possible with FAFS. We focused our attention on reactions of FAFS with aliphatic and aromatic alcohols, acyl halides, halides, H2O2, ketones and radicals whose synthesis and reaction mechanisms will be presented and discussed. Particular attention will be devoted to the novel diallyl-fluoroalkyl peroxide obtained. Factors such as pKa and Lowry and Pearson’s Hard/Soft Acid-Base Theory which determine the selectivity between Addition/Elimination vs. Nucleophilic Substitution reaction mechanisms on FAFS will also be presented and discussed.

1.08 – Amorphous Perfluoropolymer Membranes

The low energy consumption and the technological simplicity of the membrane-separation processes has led, in the last two decades, to a significant development of these technologies for industrial separations of mixtures of gases and liquids. Among the different types of membranes available in the market, those based on fluoropolymeric materials are of increasingly greater interest thanks to some unique properties, such as their excellent stability in harsh conditions, that is, in the presence of strong reactive chemicals and high temperatures. Moreover, amorphous perfluoropolymers, having a high solubility in fluorinated solvents, can be advantageously used for the preparation of membranes both by solution and by melt processing. The simplicity of the membrane-separation process and the possibility of production of membranes with different selectivities make them very promising for a wide range of applications. In this chapter, a review of the developments in the field of amorphous perfluoropolymeric membranes, with both hydrophobic and hydrophilic character, is presented and discussed.

Photochemical fluorinations of functional derivatives of perfluoropolyethers

Abstract One of the main technological problems in the manufacturing of inert fluorinated oils is the final removal of the carbonylic and carboxylic functional groups from the products. The intermediate products of the industrial processes are acidic mixtures of perfluoropolyethers bearing at one end of the chain a ketone or an acyl fluoride group. To obtain a neutral product a thermal treatment is required in the presence of elemental fluorine (1, 2, 3). We recently developed a neutralization process, comprising a photochemical fluorination which is much milder and easier to control than the thermal process [4, 5]. During this work many aspects were delineated for the reactions between fluorine and perfluorocarboxylic acids, acyl fluorides or ketones. Also fluoroformates, R f OCOF, showed an interesting reaction sequence. The stability of the perfluorinated polyether chains makes the fluorination extremely selective at the carbonylic position and consequently, the product distributions are simple and the reaction paths easy to understand.