Tris antimony, formation

Kinetically controlled conditions favor the formation of mixed fluorinated compounds if per-halo derivatives are fluorinated with hydrogen fluoride. Therefore, catalysts or coreagents are used to overcome this problem. Thus, selective fluorination of l,3-bis(trichloromethyl)benzene cannot be achieved by hydrogen fluoride using variations in temperature, pressure or time.247 However, if antimony(V) fluoride is added to hydrogen fluoride the reaction produces l-(tri-chloromethyl)-3-(trifluoromethyl)benzene. Selective fluorination can also be performed in compounds with different substitution patterns.247,251 253... 

The dismutation of 1.1.2,3-tetrachloro-3,3-difluoroprop-l-ene (7) with the double bond in the allylic position is described as a dual step reaction since all three possible products are formed.37 An attempt to coproportionate hcxachloroprop-l-ene and 1,1,2-trichloro-3.3,3-tri-fluoroprop-l-ene using antimony(V) chloride did not yield any evidence for the formation of 1,1,2.3.3,-pentachloro-3-fluoroprop-l-ene or 1, l,2.3-tetrachloro-3,3-difluoroprop-l-ene.3K... 

Even antimony pentafluoride is able to add across the C=C bond. As shown [124], reaction with CH2=CF2 results in the formation of an additional product -tris(/ , p, /)-trifluoro-ethyl)antimony difluoride. Formation of the alkenyl derivatives of antimony in reaction with CF2=CC1-CF=CF2 (Eq. 75) is another example ... 

The formation of acyloxonium derivatives (35) of (l,2/3)-cycIo-hexanetriol from tri-0-acetyI-(l,3/2)-cyclohexanetriol and antimony pentachloride does not proceed in a manner analogous to the pathway 30 - 31. In this triol system, in its favored conformation, all three substituents are equatorially disposed. The neighboring-group reaction leading to splitting out of an acetate anion requires, however, a diaxial orientation of the substituents reacting. It is understandable that this reaction should proceed considerably more slowly, because of the expenditure of energy required for conversion of the triol into its all-axial conformation. 

Sterically hindered tris[(hydroxyphenylthio)phenyl]phosphites, e.g., P[OPh( butyl)(methyl)SPh( butyl)(methyl)OH]3 (Hostanox OSP-1 Clariant), said to be especially useful in antimony oxide catalysed polyesters as they prevent formation of antimony metal and its associated grey discoloration [44] ... 

Pyrimidine bases can be less reactive than purines in these processes, but the tri-O-acetyl-D-galactal-derived compounds 51 have been obtained (a, 40% (3, 24%) by use of bis-0-(trimethylsilyl)uracil in ethyl acetate with antimony pentachloride as catalyst, the -anomer being required for the synthesis of an antibiotic [83]. Although trace proportions of 3-substituted glycals are present in the products of this reaction, their formation from the initial 2,3-unsaturated compounds is apparently less easy than is the case with the purine analogues. 

Trialkyltin alkoxides also react with ketene with formation of the normal insertion product antimony tris-alkoxides react with ketene to give a tris ester and triphenyllead acetate reacts with ketene in ethanol to give ethyl (triphenyllead)acetate . 

Analogous to the free-radical hydroxylation using tris(phenylthio)antimony, the trapping of radicals derived from O-acyl-thiohydroxamates with tris(phenylthio)phosphorous proceeds via a free-radical chain process (Scheme 15). The formation of the thiophosphonate end product is the result of a consecutive rearrangement of a pentavalent intermediate under the reaction condition and hydrolysis under aqueous work-up. 

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