Polymerization, hydrogen fluoride

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,... 

Other Polymerization Methods. Although none has achieved commercial success, there are a number of experimental alternatives to clay-catalyzed or thermal oligomeriza tion of dimer acids. These iaclude the use of peroxides (69), hydrogen fluoride (70), a sulfonic acid ion-exchange resia (71), and corona discharge (72) (see Initiators). 

Chemical Reactivity - Reactivity with Water Reacts vigorously to form toxic hydrogen fluoride (hydrofluoric acid) Reactivity with Common Materials When moisture is present, causes severe corrosion of metals (except steel) and glass. If confined and wet can cause explosion. May cause fire in contact with combustible material Stability During Transport Stable Neutralizing Agents for Acids and Caustics Flush with water, rinse with sodium bicarbonate or lime solution Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

A polymeric form of the reagent from hydrogen fluoride and poly(4-vinylpyndine) is especially easy to handle [I0 Other tertiary amines can also be employed [II], and a two-phase mixture of hydrogen fluoride-melamine-pentane hydrofluorinates cyclohexene to fluorocyclohexane m 98% yield [12]... 

Reactions of alcohols with sulfur tetrafluoride, because of decomposition and/or polymerization, usually do not give fluorinated products However, in the presence of a hydrogen fluoride scavenger like triethylamine or pyridine, even such sensitive substrates as benzylic alcohols [555], 2-phenylethanol, and 2-furylmethanol [554] can be fluorinated to give the expected fluoro derivatives (equation 73)... 

Catalysts like hydrogen fluoride or aluminum chloride catalyze not only the alkylation but the side reactions such as polymerization, isomerization, and disproportionation of tetrapropylene. All three side reactions are observed. In... 

Although vinyl fluoride was prepared around 1900, it was believed to be resistant to typical vinyl polymerization. German scientists prepared vinyl fluoride through reaction of acetylene with hydrogen fluoride in the presence of catalysts in 1933. 

The acid catalysts include sulfuric acid, phosphoric acid, hydrogen fluoride, dihydroxyfluorboric acid, and alkanesulfonic acids. Some heavy metal sulfates, phosphates, sulfides and other salts are also catalysts it seems probable that they undergo partial reduction to acidic compounds during the polymerization reactions. 

The polymerization of olefins in the presence of halides such as aluminum chloride and boron fluoride but in the absence of hydrogen halide promoter may also be described in terms of the complex carbonium ion formed by addition of the metal halide (without hydrogen chloride or hydrogen fluoride) to the olefin (cf. p. 28). These carbonium ions are apparently more stable than those of the purely hydrocarbon type the reaction resulting in their formation is less readily reversed than is that of the addition of a proton to an olefin (Whitmore, 18). Polymerization in the presence of such a complex catalyst, may be indicated as follows (cf. Hunter and Yohe, 17) ... 

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... 

The polymerization products of propylene have been observed to be saturated hydrocarbon polymers and terpenelike unsaturated hydrocarbons (Kuhn, 64). The condensation of formaldehyde with phenols and cyclohexanols by means of aqueous hydrogen fluoride has also been observed (Badertscher el al., 65). 

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... 

Carbon monoxide will also add to aromatic coumpounds such as benzene and toluene. As the product of such an addition is an aldehyde and as aromatic aldehydes readily polymerize under the conditions necessary for the addition of carbon monoxide, the simple addition product is not obtained. These reactions have been performed in the author s laboratory using a technique similar to the addition to alcohols and alkyl halides. The products obtained are the same shellac-like resins that are obtained by treating the theoretically expected aldehyde with hydrogen fluoride under the same conditions. 

Hydrogen fluoride also is used as a catalyst in alkylation of aromatic compounds and for dimerization of isobutene. Other catalytic applications are in isomerization, polymerization, and dehydration reactions. Other uses are in... 

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