Fluorine, physicochemical

Physicochemical Impact of Fluorine Substitution on Hydrolytic Processes... 

This chapter presents the state of the art of the use of highly fluorinated liquids in ophthalmology and perspectives of future applications in the eye. In different medical disciplines, the characteristics of these fluids are directly used, like in the case of ocular endotamponades in ophthalmology, of gas carriers in liquid ventilation, or of preservation and transport media in transplantation medicine [1-3]. For these applications, the highly fluorinated liquids are used in a purified form or as mixtures. The intended effect is created by the physicochemical characteristics themselves. The extraordinary behaviour of the fluorocarbon liquids (FCLs) requires specialised biocompatibility testing, adjusted to this class of components. 

This chapter deals with modifications of the physical and chemical properties of an organic molecule, which are induced by the replacement of hydrogen atoms by fluorines. These changes in the physicochemical properties play an important role in the behavior of the molecule when it is put into a biological environment. 

Physicochemical Properties of Biodiesel. - The redox characteristics of biodiesel make it a reducing agent for materials, such as brass, bronze, cooper, lead, tin and zinc. For this reason, contact of biodiesel with these materials must be avoided.Materials such as aluminum, steel, fluorinated polymers and Teflon do not react with biodiesel and can be used to handle it. In addition, biodiesel shows mild solvent properties hence, biodiesel contact with painted or varnished surfaces as well as rubber devices, such as hoses, seals and gaskets, may cause problems. 

Physical and Physicochemical Properties (of Fluorinated Organic Compounds] ... 

Smart BE (1995) Properties of Fluorinated Compounds, Physical and Physicochemical Properties. In Hudlicky M, Pavlath SE (eds) Chemistry of Organic Fluorine Compounds II, ACS Monograph 187. American Chemical Society, Washington, D. C, p 979... 

Abstract This article summarizes a large amount of work carried out in our laboratory on polysiloxane based Interpenetrating Polymer Networks (IPNs). First, a polydimethylsiloxane (PDMS) network has been combined with a cellulose acetate butyrate (CAB) network in order to improve its mechanical properties. Second, a PDMS network was combined with a fluorinated polymer network. Thanks to a perfect control of the respective rates of formation of each network it has been possible to avoid polymer phase separation during the IPN synthesis. Physicochemical analyses of these materials led to classify them as true IPNs according to Sperling s definition. In addition, synergy of the mechanical properties, on the one hand, and of the surface properties, on the other hand, was displayed. 

The nature of C—F bonds that are formed during the reaction between F species and C materials depends on two main factors (i) the experimental conditions of fluorination (low-pressure plasmas, F2-gas, fluorinated media) and (ii) the physicochemical characteristics of the pristine materials (graphitisation level, morphology). 

Kharitonov AP, Moskvin YL, Syrtsova DA, Starov VM, and Teplyakov VV. Direct fluorination of the polyimide Matrimid 5218 The formation Kinetics and Physicochemical properties of the Fluorinated layers. J. Appl. Pol. Sci. 2004 92 6-17. 

The uncommon structural artemisinin framework, and the well-known difficulty in selectively introducing a fluorinated motif into a molecule, faced us with numerous chemical challenges. The evaluation of the effects of fluorine on physicochemical and antima-larial properties is reported. These data and preclinical data of lead compounds are encouraging, with strong and prolonged antimalarial activity of fluoro-artemisinins. 

The quest for methods of synthesizing chiral fluoroorganic compounds is one of the most fascinating topics in modern organofluorine chemistry because the replacement of hydrogen with a fluorine atom often results in a significant improvement in the physicochemical properties and biological activities of the molecules. 

This section discusses how the fluorine atom influences the physical and physicochemical properties of organic fluorine compounds. One of the most important factors for a better understanding of such properties would be the low electronic polarizability (refractive index) of the molecules. Of course, we cannot disregard other effects such as the strong electron-withdrawing effect and stiff nature of the perfluoroalkyl moiety. 

Discussion of the physicochemical sizes of substituents on the basis of conformational analysis of the torsional process of substituted cyclohexanes, cyclophanes, and diaryl derivatives have been summarized by Schlosser [5]. The energies required for the conformational exchange of an equatorial position to the axial position for each substituent in cyclohexane are listed in Table 1.47 [6]. For fluorine, the energy difference between the axial and equatorial environment is negligibly small as compared with methyl, while that of CF3 seems larger than that of z-Pr so far observed in the cyclohexane torsional system. From the... 

Morita M, Kubo M, Matsumoto M. Interfacial properties and emulsification in systems of perfluoropolyether/nonfluorinated oil/partially fluorinated oligomeric and polymeric compounds. Colloids Surfaces A Physicochem Eng Aspects 1996 109 183-194. 

Also, fluorine-carbon composites were investigated as functional coating materials in a wide variety of applications coating materials for construction under low temperature environments [139], protective coating for computer hard disks [140], automotive components [141], semiconductor in opto-electronic devices [142, 143], and biomedical implants [144]. Those applications follow outstanding physicochemical, electrical and mechanical properties of these materials, (i.e., hardness, friction, water repellency, chemical... 

Biological Properties of Fluorinated Imidazoles The importance of the imidazole ring in biological structure and function combined with the profound effects on physicochemical properties that result from fluorine substitution combine to make fluorinated imidazoles a class of compounds with a wide range of biological... 

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