Silver trifluoroacetate preparation

Tfifluorovinyl- and ( 0-pentafluaropropenylsilver compounds can be prepared via the exchange reaction of the corresponding cadmium compound with silver trifluoroacetate [144] (equation 189) The 2-pentafluoropropenyl silver compound can be synthesized via a similar exchange reaction of silver tnfluo-roacetate with 2-pentafluoropropenyllithium [279]... 

Unsymmetrical dialkyl peroxides can be prepared by several methods. Some of them are summarized in Scheme 31. Primary " , secondary or tertiary"" " alkyl hydroperoxides can serve as substrates and are converted to the dialkyl peroxides by acid- or base-catalyzed nucleophilic substitution with alkylating agents like dialkyl sulfate " , diazomethane " , dialkyl sulfites, alcohols " or alkyl halides (e.g. in the presence of silver trifluoroacetate) "". An overview of the results obtained utilizing the method mentioned above is given in Table 7. 

Silver salts of triphenylarsine and triphenylstibine have also been prepared. When silver trifluoroacetate was added to a methanol-water solution of triphenylarsine, a change due to complexation was observed in the UV spectrum. The trifluoroacetate was assumed to be completely dissociated and a 1 1 complex with the arsine formed. The stability constant at 25 °C was determined as log / i = 5.7-5.8.203... 

A photochemical preparation of a Cephalotaxus alkaloid synthon (20) has been reported (Scheme 2).10 The readily accessible maleimide (17) was iodinated with iodine and silver trifluoroacetate, in 71% yield, and the resulting compound was transformed in two steps (70% overall yield) into the methylene-pyrrolone (18) by the action of methylmagnesium iodide followed by dehydration. Irradiation of (18) afforded (19) (46% yield), which, by successive hydrogenation and reduction with lithium aluminium hydride, gave the dihydro-pyrrolo[2,l-b][3]benzazepine (20). This derivative has served as a key intermediate in the total synthesis of cephalo-taxine described previously (see Vol. 7 of these Reports). 

Phenylselenenyl trifluoroacetate, prepared in situ by the addition of phenylselenenyl chloride or bromide to silver trifluoroacetate in benzene, undergoes virtually instantaneous addition to alkenes giving /3-trifluoroacetoxy selenides 39 in quantitative yields51. When ( )- or (Z)-2-butene or cyclohexene is used as the alkene then anti or trans addition only is observed, however, 1,3-cyclohexadiene gives predominantly trans-1,2 addition together with a small amount of a 1,4-adduct (Table 6)51. 

The preparation of pure acetyl trifluoroacetate for the infrared studies referred to above was achieved by (a) fractional distillation of an equimolecular mixture of acetic anhydride and trifluoroacetic anhydride, or (b) the addition of pyridine to a mixture of acetic acid and trifluoroacetic anhydride, and fractional distillation of the filtrate. Acetyl trifluoroacetate is a colorless liquid, b.p. 95°, which gradually becomes colored on standing. In solution in carbon tetrachloride or other inert solvent, no coloration occurs and the solutions are stable. Similar methods of preparation have been used by other workers, and several different acyl trifluoroacetates have been reported. A different procedure for the preparation of acyl trifluoroacetates is the addition of the appropriate acyl chloride to a solution of silver trifluoroacetate in ether. The unsymmetrical anhydrides were found to be stable during the subsequent distillation, but disproportionation occurs in the presence of silver trifluoroacetate. 

Silver trifluoroacetate. For use in combination with iodine for the 4-iodination of veratrole," the salt is prepared by adding trifluoroacetic acid to a suspension of precipitated silver oxide in water, filtering, and evaporating the filtrate to dryness. Extraetion of the dry salt with ether in a Soxhiet and evaporation of the solvent gives colorless, crystalline material in 88% yield. 

The preferred procedure for iodination of veratrole employs silver trifluoroacetate. An aqueous solution of the salt is prepared from the acid and silver oxide, filtered, and evaporated to dryness the salt is purified by Soxhlet extraction with ether. A solution of iodine in chloroform is added with stirring under reflux to a mixture of... 

Trifluoroacetyl hypohalites, CFaCOzX. Prepared by interaction of bromine or iodine with silver trifluoroacetate. ... 

Siphonodicidine, a natural sesquiterpene containing a 2,4-disubstituted furan as a substructure, was synthesized in a regioselectivity-controlled manner. The key intermediate was prepared by the coupling of a silyloxyfuran with a bromogeranyl acetate in the presence of silver trifluoroacetate followed by reduction and hydrolysis as depicted in the following scheme <04JNP1383>. 

Preparation of silver trifluoroacetate from silver oxide and trifluoroacetic acid in water, and purification of the crude evaporation residue by extraction with ether, are described in Organic Syntheses 1 ... 

The most useful method is reaction of ketone (and ester) hthium enolates, usually prepared by deprotonation of ketones with LDA, with either Ce H5 SeBr or Ce Hs SeCl. Enol acetates can be converted into a-phenylseleno ketones by reaction with phenylselenenyl trifluoroacetate, prepared in situ by treatment of CeHsSeCl or CeHsSeBr with silver trifluoroacetate or by conversion to the lithium enolate and reaction with CeHsSeBr. It is sometimes possible to obtain isomeric a-phenylseleno ketones by use of these two methods (equations 1 and II). 

Although one might expect thiol (RSH) complexes to be more stable than HjS complexes, only a few well characterized examples have been reported. The analogs of the Ru" compounds (1) and (2) with EtSH have been prepared. By oxidation with silver trifluoroacetate the corresponding pentaammine-Ru complex can be obtained. Spectral evidence for the formation of thiol complexes has also been given, e.g. for the systems Fe"/PrSH and PhSH, Zn /BuSH and [Pt(pyz)Cl2]/ PhSH however, no further descriptions of the complexes were given,... 

Nickel-coated poly-p-phenylene terephthalamide film was prepared as follows. A section of poly-p-phenylene terephthalamide film was immersed momentarily in a 0.1 M solution of K+ 0-t-Bu in DHSO and then in a 0.1 M solution of silver trifluoroacetate in DHSO. The film was washed liberally with water and dried. Nickel was plated onto this silver-activated film using a known method of electroless plating as follows a section of film weighing 0.038 g was immersed in a solution of 5.0 g of nickel chloride hydrate and 0.2 g of dimethyl amine borane in a mixture of 50 mL of water and 50 mL of dimethyl formamide for 1.5 hrs. The film was then rinsed liberally with water and dried in a vacuum oven at 110 C for 2 hrs. The resulting nickel coated film weighed 0.095 g and was electrically conductive. 

Copper-coated poly-p-phenylene terephthalamide fibers and films were prepared by the following procedure. The fibers and films were immersed in a solution of 0.1 a K+-CH2S (0)CH3 in DHSO for several seconds at room temperature and then into a solution of 0.1 U silver trifluoroacetate for several seconds at room temperature. The fibers and films were rinsed with water and dried by means of a vacuum. The fibers and films were then immersed for several seconds into a copper electroless plating bath consisting of 22.7 g of copper sulfate penta-hydrate, 12.5 g of sodium carbonate, 70.0 g of sodium potassium tartrate, and 9.0 g of ethylene diamine tetraacetic acid all in 400 mL of deionized water to which was added a Solution of 20.0 g of sodium hydroxide in 100 mL Of water and 65 mL of a 37% formaldehyde solution. The fibers and films were then rinsed with water and dried. 

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