Hydrogen fluoride, polymerization liquid

Properties. Antimony pentafluoride [7783-70-2], SbF, is a colorless, hygroscopic, very viscous liquid that fumes ia air. Its viscosity at 20°C is 460 mPa-s(=cP) which is very close to the value for glycerol. The polymerization of high purity SbF at ambient temperature can be prevented by addition of 1% anhydrous hydrogen fluoride, which can be removed by distillation prior to the use of SbF. The pure product melts at 7°C (11), boils at 142.7°C,... 

The term hydrogen fluoride is used as the name for the substance containing hydrogen and fluorine, and the formula HF used regardless of the fact that the vapor has been shown to exist as an equilibrium of polymers. By implication the liquid and crystalline material are even more highly polymerized. When emphasis is needed to call attention to the fact that water free material is designated, the term anhydrous hydrogen fluoride is used. The term anhydrous hydrofluoric acid is self-contradictory as hydrofluoric acid is the name for the aqueous solution. In addition, completely anhydrous material is not always necessary or even desirable for catalytic work. The commercial material labeled anhydrous... 

In the author s laboratories the polymerization of aldehydes, ketones, and alcohols by liquid hydrogen fluoride has been repeatedly noted. Acetaldehyde polymerizes and acetone forms polymeric substances on standing for a period of time in solution in hydrogen fluoride. If the solution is separated shortly after mixing, the acetone may be recovered. The same is true of tertiary alcohols. The peculiar action of tertiary chlorides (Simons et al., 35) probably results at least in part from polymerization. The products obtained most likely come from destruction of the polymers in the process of distillation. Benzaldehyde forms a shellac like resin when treated with hydrogen fluoride. A rather interesting polymerization reaction occurs upon treating aralkyl ketones with... 

This technique is useful for monomers which are difficult to polymerize by other techniques. Thus, chlorotrifluoroethylene can be polymerized anodically with good efficiency by electrolysis in liquid hydrogen fluoride - potassium fluoride or trifluoroacetic acid - trifluoroacetic anhydride - potassium trifluoroacetate 631 ... 

It should be possible to replace the dangerous hydrogen fluoride with a solid acid in a solvent-free process. Two possibilities are the U.O.P.-Petresa catalyst and a high-sur-face-area polymeric perfluorosulfonic acid.319 (These may require a film of liquid acid on the surface to prevent deactivation of the catalyst.)... 

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