Triethyloxonium hexachloroantimonate

Lyudvig, Rozenberg et al. (41) made a study of the kinetics of THF polymerization initiated by triethyloxonium hexachloroantimonate. 

They carried out their measurements at 20° C in bulk. They report (31) that in this case it was necessary to use the preformed salt. When the catalyst was added in the form of two components, initiation was not complete. The kinetics were analogous to those discussed above. An activation energy of 15.0 kcal/mole was derived. Equation 42 was followed. The plot of log(M0 — Me)j(M — Me) against time (compare equation 43) is shown in Fig. 12. 

Saegusa, Furukawa et al. (48,66) carried out kinetic studies of THF polymerization in bulk and in cyclohexane solution at 0° C. They used a ternary catalyst system consisting of AlEt3-H20(2 l)-epichloro-hydrin (ECH). They obtained high molecular weight polymer and noticed no evidence for either termination or transfer. Their polymerizations were preceded by an induction period as shown in Fig. 13 but after that their data could be fitted to an equation of the same form as equation 42. This time [f0] was defined as the concentration of propagating species ([P ]) determined from the amount and the molecular weight of product polymer. 

The concentration of propagating species was found to be proportional to the amounts of AlEt3 and of ECH used, so equation 42 now takes the form  

These workers found this relationship to hold as long as [ECH]0/ [AlEt3]0 0.07. Beyond this region the linear relationship did not hold and the 

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Crystalline cation-radical salts are generally isolated via three preparative procedures by using a nitrosonium (NO+) salt, antimony pentachloride (SbCIs), or triethyloxonium hexachloroantimonate (Et30+SbCl ) as a mild one-electron oxidant. 

Triethyloxonium hexachloroantimonate is a selective and mild one-electron oxidant for the facile preparation and isolation of crystalline cation-radical salts from a variety of aromatic and olefinic donors.177 Thus, in a general procedure, a slurry of Et30 + SbCl (3 mmol) and dimethoxytriptycene, DMT (2 mmol) is stirred in dichloromethane at 0°C. The heterogeneous mixture immediately takes on a bright yellow-green coloration (lmax = 466 nm), and on continued stirring (for about 1 h) it is transformed to yield a dark solution of DMT+. The highly pure DMT+ SbCl salt is isolated in quantitative yield by precipitation with diethyl ether (equation 38). 

As far as the polymerisations of DCA other than DXL by non-protonic initiators are concerned, Kops and Spanggaard [11] favour the ring expansion mechanism for the dimerisation and polymerisation of the cis- and tnms-7,9-dioxabicyclo[4.3.0] nonanes by phosphorus pentafluoride or triethyloxonium hexachloroantimonate, although they have not obtained any definitive evidence for it. 

More recently (55) triethyloxonium hexachloroantimonate has also been used as an initiator of the polymerisation of this monomer, and its dissociation constant determined as 5.3 x 10 5 M at 20° C in methylene chloride. Penczek (54) has also studied the dissociation of l,3dioxolan-2-ylium hexafluoroarsenate and hexa-fluoroantimonate,... 

In a recent article (59) Kops and Spanggaard report that m-7,9-dioxabicyclo[4,3,0]-nonane is transformed quantitatively into the cyclic dimer when treated with a catalytic amount of phosphorous pentafluoride or triethyloxonium hexachloroantimonate. From an NMR study the dimer was concluded to have the cis-anti-as structure. 

Carbon-14-labelled triethyloxonium hexachloroantimonate, [( 3115)2002115] (SbClg)", 18 (specific activity 1.15 x 10 Bq g ), has been obtained by treating the C-labelled ( 2115)20 Sb l5 complex with ethyl chloride. The salt was used to clarify the mechanism of initiation of polymerization of 2,3,4-tri-O-methyl-L-glucosane (19) , since it has been noted" " " that the incorporation of the radioactive label into the polymer increases with the increase in the degree of conversion of the monomer (at 10. 5% of the equilibrium yield of the polymer, 2.5% of the initial radioactivity of 18 has been... 

If a reagent with an electrophilic C-atom is added instead of a proton to a a-diazo-)S-carbonyl compound a much more favorable equilibrium is obtained. Bott (1964, 1966) added the Meerwein reagent triethyloxonium hexachloroantimonate to ethyl diazoacetate (2.274) and to (4-nitrophenyl)-diazoacetic-acid piperide (2.276) and obtained the isolable alkenediazonium salts 2.275 and 2.277 (2-105 and 2-106). 

Other combinations of trialkyloxonium and Lewis acid are added to this group of salts, including triethyloxonium hexachloroantimonate (Et30+SbCl6 ) and triethyloxonium hexafluorophosphate (Et30 PF6 ). ... 

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