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Other electrophilic aromatic substitution reactions can also be promoted with trifluoroacetic anhydride, including nitration, sulfonation and nitrosylation. [2] Similar to acetic anhydride, trifluoroacetic anhydride can be used as a dehydrating agent and as an activator for the Pummerer rearrangement. [4]
Trifluoroacetic acid in a beaker. TFA is the precursor to many other fluorinated compounds such as trifluoroacetic anhydride, trifluoroperacetic acid, and 2,2,2-trifluoroethanol. [4] It is a reagent used in organic synthesis because of a combination of convenient properties: volatility, solubility in organic solvents, and its strength as an ...
As the anhydride will form trifluoroacetic acid in contact with water, an excess of the anhydride also serves to remove the solvent from the peroxide reactant: [9] CF 3 COOCOCF 3 + H 2 O → 2 CF 3 COOH. A more dilute hydrogen peroxide solution (30%) can be used to form trifluoroperacetic acid for some reactions from trifluoroacetic acid. [2] CF
When using oxalyl chloride as the dehydration agent, the reaction must be kept colder than −60 °C to avoid side reactions. With cyanuric chloride [11] or trifluoroacetic anhydride [12] instead of oxalyl chloride, the reaction can be warmed to −30 °C without side reactions.
When a substituent on the α position can form a stable carbocation, this group rather than the α-hydrogen atom will eliminate in the intermediate step. This variation is called a Pummerer fragmentation. [10] This reaction type is demonstrated below with a set of sulfoxides and trifluoroacetic anhydride (TFAA): Pummerer fragmentation
The mechanism of the Boekelheide reaction begins by an acyl transfer from the trifluoroacetic anhydride to the N-oxide oxygen. The α-methyl carbon is then deprotonated by the trifluoroacetate anion. This sets the molecule up for a [3.3]-sigmatropic rearrangement which furnishes the trifluoroacetylated methylpyridine. Hydrolysis of the ...
Triflic acid catalyzes the reaction of aromatic compounds with sulfonyl chlorides, probably also through the intermediacy of a mixed anhydride of the sulfonic acid. Triflic acid promotes other Friedel–Crafts-like reactions including the cracking of alkanes and alkylation of alkenes, which are very important to the petroleum industry.
The following figure shows the reaction mechanism: [2] Reaktionsmechanismus Albright-Goldman-Oxidation. First, dimethyl sulfoxide (1) reacts with acetic anhydride to form a sulfonium ion. It reacts with the primary alcohol in an addition reaction. Furthermore, acetic acid is cleaved, so that intermediate 2 is formed. The latter reacts upon ...