Trichlorofluoromethane as solvent

Interaction is explosive, after a delay, in either tetrahydrothiophene-1,1-dioxide (sulfolane) or trichlorofluoromethane as solvent, on 0.15 g mol scale, though not on one tenth this scale. 

The reaction of diazo compounds with an electrophilic fluorinating reagent, tri-fluoromethyl hypofluorite. has also been studied (Tabic 8, entries 9 13). ° The reactions are carried out at — 70 C using trichlorofluoromethane as solvent and mixtures of g /n-difluoro compounds and fluoro(trifluoromethoxy) derivatives are obtained. Although conversion is generally complete, the yields of isolated products are low, due to their difficult separation. In some cases (entries 9, 11, and 12), ketones and epoxides arc formed as byproducts. Consequently, this method is not a useful alternative for the preparation ofgcw-difluoro compounds. 

The addition of molecular fluorine to phenylacetylenes in trichlorofluoromethane as solvent yields the corresponding tetrafluorides as the main product, e.g. 2, while the use of methanolic solutions leads to the formation of rem-fluoro ethers 3 and dimethyl ketals 4 as well as tetrafluorides 2. ... 

For the preparation of higher-boiling fluorides, lower-boiling solvents, such as pentane, di-chloromethane, or trichlorofluoromethane, are useful. 

Foams may be prepared by either one of two fundamental methods. In one method, a gas such as air or nitrogen is dispersed in a continuous liquid phase (e.g. an aqueous latex) to yield a colloidal system with the gas as the dispersed phase. In the second method, the gas is generated within the liquid phase and appears as separate bubbles dispersed in the liquid phase. The gas can be the result of a specific gasgenerating reaction such as the formation of carbon dioxide when isocyanate reacts with water in the formation of water-blown flexible or rigid urethane foams. Gas can also be generated by volatilization of a low-boiling solvent (e.g. trichlorofluoromethane, F-11, or methylene chloride) in the dispersed phase when an exothermic reaction takes places, (e.g. the formation of F-11 or methylene chloride-blown foams). 

Sulfuric acid and oleum are often used in excess, thereby advantageously functioning as cheap, low-viscosity solvents for the product sulfonic acids which are often quite viscous in pure form. They are always used in liquid form, while sulfur trioxide, on the other hand, is usually employed as a vapor since it is easily vaporized (bp, 44.8°C) and the vapor form is considerably milder than the liquid. Liquid sulfur dioxide is an excellent sulfonation solvent for use with sulfur trioxide and with oleums, and it has been used industrially. Halogenated organic solvents (tetrachloroethylene, carbon tetrachloride, trichlorofluoromethane, etc.) are miscible with sulfur trioxide in all proportions, but not with its hydrates. 

Halomethanes have numerous industrial applications (Table 3.2). One of the most important of the group, chloroform, is used mainly as a solvent and an intermediate in the production of various products. Chloromethane and tribromomethane are also employed as chemical intermediates, whereas dichloromethrae is widely used as a solvent. Tribromomethane is a common fumigant, and fluoro-derivatives find general application as refrigerants and aerosol propellants. Recent restrictions placed on the use of fluorocarbons have resulted in a decrease in US production of fluoro-derivatives. During the last decade, production of trichlorofluoromethane declined from 1.3 to 0.7 X 10 tons while dichlorofluoromethane fell from 2.0 to 1.5 X 10 tons (Table 3.1). Production of other halomethanes has shown a consistent albeit small increase in recent years (Table 3.1). Total dichloromethane production now exceeds 2.5 X 10 tons compared with 1.5 and 1.8X itf tons for chloromethane and chloroform, respectively. It is estimated that bromo-methane production will be only about 2.0 X 10 tons in 1982. 

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