Polymerization with Antimony Pentachloride

Antimony pentachloride, SbCls, is a liquid having a freezing point of 2.8 °C and a boiling point of 140 °C. When absolutely pure, the liquid is colorless, but commercial SbCls is usually yellowish. SbCls has a high density (2.35 g/cc), and in humid air its vapor reacts with water to form visible fumes of hydrochloric acid mist and Sb20s particles  

As catalyst for the polymerization of THF, SbCls works by self-ionization [88] according to the equilibrium 

The polymerization of THF with SbCls starts in the same fashion as with fluosulfonic acid except that 250 ml of THF require only 15 ml of SbCls (instead of 30 ml of fluosulfonic acid). The addition of the SbCls causes the THF to assume a yellow to brown color. Some toluene is added to prevent any sudden rise in viscosity. A water bath is employed to take the mixture of THF, SbCls, and toluene to 40 °C for a period of 3 hours. During this time, the viscosity will be seen to increase significantly. 

To terminate the rection, 40 ml of aqueous Ca(OH)2 solution is added. Then the SbCls is decomposed by boiling the mixture under reflux for a period of 30 minutes. This leads to a formation of Sb203 and to a venting of chlorine. Subsequently, the mixture is concentrated in a rotary evaporator until all of the water is distilled off The remaining 

Fluosulfonic acid provides the positive charge by its hydrogen atom highly depleted of electrons, and it can be removed, though not conveniently, by extraction. Antimony pentachloride provides the positive charge by its self-dissociation into SbCU and SbCU , and can be removed by decomposition. 

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PPSA can also be obtained by the condensation of methyl-(4-anilino-phenyl) sulfide with antimony pentachloride." The reaction proceeds in chloroform at —68°C. The process is shown in Figure 5.7. After polymerization, a demethylation step follows as shown in Figure 5.6. 

Bushby reported several aminium-based polymers (22). Polyamine 5a (Mw > 10, GPC) was prepared by Suzuki reaction based polymerization, and then p-doped with antimony pentachloride. The resultant polyaminiiun polymer 5b had radical concentration of 0.5 radical/imit and an average value of S 4 (22). The ferromagnetic coupling was rather weak, as expected for extended exchange pathway of m-phenylene with two jo-phenylene spacers (Fig. 3). 

The polymerization of 1,3,3-trimethyl-2,7-dioxabicyclo[2.2.1 Jheptane 35 was carried out in methylene chloride, toluene, and 1-nitropropane at temperatures between —78 and 0 °C32l Boron trifluoride etherate, triethyloxonium tetrafluoro-borate, antimony pentachloride, and iodine were used as initiators. Irrespective of the solvents and initiators employed, the products obtained at 0 °C were white powders with melting points of 50—55 °C, while those obtained at tower temperatures were sirups. The number average molecular weight of the unfractionated products ranged from 400 to 600. The molecular weight distribution of the oligomers prepared at 0 °C was broad, in contrast to the relatively narrow distribution of those obtained at -40 °C. 

THF can be polymerized only with cationic initiators, for example, boron trifluoride or antimony pentachloride. The initial step consists of the formation of a cyclic oxonium ion one of two activated methylene groups in the a-position to the oxonium ion is then attacked by a monomer molecule in an S 2-reaction, resulting in the opening of the ring. Further chain growth proceeds again via tertiary oxonium ions and not, as formerly assumed, via free carbonium ions ... 

The initiation of tetrahydrofuran polymerization by direct addition of oxonium salts is of interest because it reveals a good deal about the mechanism, but for practical purposes the salts may be formed in the reaction mixture. The obvious method is, of course, to add a little epichlorohydrin to the mixture of monomer and Friedel Crafts reagent for only antimony pentachloride is sufficiently active to start the reaction with monomer alone, but other reactions which accomplish the same purpose are ... 

Compared with 49, 2,5-dioxabicyclo[2.2.2]octan-3-one (54) prepared from sodium 3,4-dihydro-2//-pyran-2-carboxylate has a much low polymerization reactivity [54] Lewis acids such as antimony pentachloride, phosphorus pentafluoride, and boron trifluoride etherate were not effective at all to initiate the polymerization of 54. Trifluoromethanesulfonic acid induced the polymerization of 54, but the yield and molecular weight of the polymer were low. Bicyclic lactone 54 was allowed to polymerize with anionic and coordination initiators such as butyl-lithium, lithiumbenzophenone ketyl, and tetraisopropyl titanate. However, the... 

Reaction of fully etherified 1,6-anhydrolactose with Lewis acids, e.g. antimony pentachloride, caused polymerization to give a comb-shaped product based on an a-l,6-linked glucose backbone with p-D-galactosyl substituents,... 

The polymerization of propiolactone in methylene chloride with an antimony pentachloride-dieth te catalyst was investigated. The results show that the concentration of the active centers is dependent upon catalyst concentration and upon the initial concentration of the monomer. They also support the concept that opening of the lactone rings includes initial formation of oxonium ions ... 

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