Fluorinated aliphatic hydrocarbons

There are liquid PBAs that are volatile and change from a liquid to a gaseous state when heated to the plastic processing temperatures. They are short-chain chlorinated and fluorinated aliphatic hydrocarbons (CFCs). Although they can be used over a wide temperature range and at low (atmospheric) pressures, they have been gradually discontinued due to their role in the reduction of stratospheric ozone.249 Other PBAs are reviewed in Table 8.2. 

Volatile liquids— These foam the resin as they change from a liquid state to a gaseous state at the high temperature of processing. The most important materials in this category are fluorinated aliphatic hydrocarbons (chloro-... 

Fluorination of aliphatic hydrocarbons with cobalt trifluoride gives complex mixtures Isobutane (2-methylpropane) fluorinated at 140-200 °C affords a mixture of 30 products of different degrees of fluorination and of isobutane as well as butane skeletons. The tertiary hydrogen is replaced preferentially Products containing 5-10 atoms of fluorine including a small amount of perfluoroisobutane were isolated [10]. 

Release agents function by either lessening intermolecular interactions between the two surfaces in contact or preventing such close contact. Thus, they can be low surface-tension materials based on aliphatic hydrocarbon, fluorocarbon groups, or particulate solids. The principal categories of material used are waxes, fatty acid metal soaps, other long-chain alkyl derivatives, polymers, and fluorinated compounds. 

Because the forces of attraction prevail when molecules are brought into sufficiently dose proximity under normal conditions, release is best effected if both the strength of the interaction and the degree of contact are minimized. Aliphatic hydrocarbons and fluorocarbons achieve the former effect, finely divided solids the latter. Materials such as microcrystalline wax [64742 42-3] and hydrophobic silica [7631-86-9] combine both effects. Some authors refer to this combined effect as the ball bearing mechanism. A perfluoroalkylated fullerene nanosphere would perhaps be the ultimate example of this combined effect (17). These very general mechanistic remarks can be supplemented by publications on the mechanism of specific classes of release agents such as metallic stearates (18), fatty acids and fluorinated compounds (19), and silicone-coated rdease papers (20,21). The mechanism of release of certain problem adherents, eg, polyurethanes, has also been addressed (22,23). 

Fluorinated Organics Hydrocarbons, aliphatic carboxylic acids, sulfonic acids, amines, etc. Dia Nippon (Japan) 3M (US)b Not available Not available Anodic substitution... 

Disproportionation of halogenatcd aliphatic hydrocarbons can also be accomplished using catalysts based on chromium oxides with the formula Cr01 2F2 1.18 This catalytic material is obtained by fluorination w ith hydrogen fluoride of an oxide hydrate of trivalent chromium with the formula Cr203 xH,0 (with x = 1-9). The chromium oxide hydrate is reacted with a mixture of hydrogen fluoride/nitrogen gas in a molar ratio of 1 10 in an externally heated nickel tubular reactor at 350 450 C. 

Another possibility for achieving attractive interactions due to fluorination could be provided by partial fluorination of aliphatic hydrocarbons. If H and F are combined at one C atom the highly polar nature of the C-F bond can cause polarization of the C-H bond at the same carbon, thus enabling attractive interactions with fluorine atoms at neighboring molecules. For example, difluoromethane has a significantly higher boiling point (—52°C) than either methane (—161°C) or tetrafluoromethane (—128°C) [59, 421],... 

Simons process — Electrochemical polyfluorination reactions of organic compounds are the only efficient way to industrial production of perfluorinated compounds. The reaction proceeds in the solution of KF in liquid HF (b.p. 19.5 °C), where the starting substances as alcohols, amines, ethers, esters, aliphatic hydrocarbons and halo-hydrocarbons, aromatic and heterocyclic compounds, sulfo- or carboxylic acids are dissolved. During anodic oxidation, splitting of the C-H bonds and saturation of the C=C bonds occur and fluorine atoms are introduced. 

Water absorption is less than 0.1wt% after 24 hours. However, PBT is not recommended for extended use in water or aqueous solutions above 52C (125F).112 PBT plastics are also intrinsically resistant to detergents, weak acids and bases, aliphatic hydrocarbons, fluorinated hydrocarbons, alcohols, ketones, ethylene glycol, carbon tetrachloride, oils, and fats at room temperature. They also exhibit good resistance to motor oil, gasoline, transmission fluids, and brake fluids at temperatures to 60C (HOF).113... 

Fluorinated Organics Hydrocarbons, aliphatic Dia Nippon (Japan) Not available Anodic substitution... 

The halogenation of saturated aliphatic hydrocarbons is usually achieved by free radical processes. Ionic halogenation (fluorination, chlorination, and bromination) of alkanes has also been reported under superacid catalysis. Reactions may be carried out either in the liquid phase or in the gas phase over solid superacids or supported noble metal catalysts. High selectivity and relatively mild reaction conditions are the main features of these transformations. 

In an alternative approach, volatile organic substrates were fluorinated in the gas phase on contact with a copper mesh. This work was pioneered by Fredenhagen and Cadenbach in the early 1930s [5] and then continued by Bigelow and Fukuhara [6] as a part of the Manhattan Project (Figure 2.1). Vapor phase fluorination finally enabled the preparation of (relatively) defined polyfluorination products from aliphatic hydrocarbons, benzene, or acetone. 

Friedel-Crafts reaction can proceed in a rather limited number of inert solvents, such as aliphatic hydrocarbons, benzene, nitrobenzene, CS2, and chlorinated or fluorinated hydrocarbons. Among these solvents, however, only chlorinated hydrocarbons, particularly EDC, nitrobenzene, as well as cyclohexane at an elevated temperature, are suited for the synthesis of hypercrosslinked polystyrene, since they are thermodynamically good solvents for both the initial polystyrene and the final products of crosslinking. 

Alkanes can be fluorinated by means of electrolysis in hydrogen fluoride. This important reaction is reviewed in Reference. Electrochemical fluorination in anhydrous hydrogen fluoride (AHF), the so-called Simons process, involves the electrolysis of organic compounds (aliphatic hydrocarbons, halohydrocarbons, acid halides, esters, ethers, amines) at nickel electrodes. It mostly leads to perfluorinated compounds. It is, however, considerably accompanied by cleavage and rearrangement reactions. As mechanism, the formation of carbocations by an ECE mechanism is assumed through oxidation of the hydrocarbon by higher-valent nickel fluorides. 

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