Fluorine physicochemical properties

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... 

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 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. 

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... 

Section 2.2 mainly reviews the papers on novel fluorinated organic solvents, which include fluorinated lactones, fluorinated linear carboxylates, fluorinated cyclic carbonates, fluorinated linear carbonates, fluorinated monoethers, fluorinated diethers, and others. The physicochemical properties of typical fluorinated compounds are summarized in comparison with nonfluorinated counterparts. 

Kausch CM et al (2002) Synthesis, characterization, and unusual surface activity of a series of novel architecture, water-dispersible poly(fluorooxetane)s. Langmuir 18(15) 5933-5938 Dams R (1993) Fluorochemical surfactants for hostile environments. Spec Chem 13(l) 4—6 Shinoda K, Hato M, Hayashi T (1972) The physicochemical properties of aqueous solutions of fluorinated surfactants. J Phys Chem 76(6) 909-914... 

Shinoda, K. et al.. Physicochemical properties of aqueous solutions of fluorinated surfactants, J. Phys. Chem., 76, 909, 1972. 

Patrick, C.R., Physicochemical properties of highly fluorinated organic compounds, Chem. Brit., 7, 154, 1971. 

Carnitine is at the origin of two types of fluorinated surfactants. The perfluoroalkyl-acylcarnitines (28) (Scheme 24), obtained with satisfactory yields (44-80%), show good surfactant characteristics [60], The synthesis of Ai-perfluoroalkyl carnitine (29) (Scheme 25) is less efficient, and its physicochemical properties have not been evaluated [61]. The betaines of perfluoro-alkyl a,co-amino acids (30) (Scheme 26) are accessible in a similar manner [62]. They are good surface agents [63]. 

Extensive research has been focused on introducing fluorine into molecules, which can modify their physicochemical properties. Nowadays, around 30% of pharmaceutical compounds contain fluorine. Several methodologies are available and are mainly based on the use of readily commercially available fluorinating reagents. Usually, for aromatic systems, the Balz-Schiemann or the Halex reactions are the processes of choice, whereas for aliphatic systems, electrophilic or nucleophilic fluorinations are required. Despite the fact that cheap starting materials are used in these processes, the harsh conditions remained an obstacle due to poor functional group tolerance. 

The practical applications of fluoropolymer membranes especially in the areas of purification and separation related to potable water production, wastewater treatment and bioprocessing, have been limited to some extent by their hydrophobic and inert surface properties. Among the different modification techniques, graft copolymerization of hydrophilic monomers, or inimers for further surface reactions, from fiuoropolymers has been useful and effective in improving the physicochemical properties of the parent fluoropolymer with minimum alteration of their desirable bulk properties. Apart from fiilly fluorinated polymers, most of the partially fluorinated polymers can dissolve in polar organic solvents, such as Ai,Ai-dimethylformamide (DMF), A,A-dimethylacetamide (DMAc), NMP, and dimethyl sulfoxide (DMSO), but are insoluble in water, alcohols, and hydrocarbons. 

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