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With cyanuric chloride [11] or trifluoroacetic anhydride [12] instead of oxalyl chloride, the reaction can be warmed to −30 °C without side reactions. Other methods for the activation of DMSO to initiate the formation of the key intermediate 6 are the use of carbodiimides ( Pfitzner–Moffatt oxidation ), a sulfur trioxide pyridine complex ...
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
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 ...
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 ...
The reaction is often carried out without a solvent (particularly when a large reagent excess of the alcohol reagent is used) or in a non-polar solvent (e.g. toluene, hexane) that can facilitate Dean–Stark distillation to remove the water byproduct. [4] Typical reaction times vary from 1–10 hours at temperatures of 60–110 °C.
Reaction with the nearby cis alcohol is the key obstruction, and can be inhibited by pretreatment with trifluoroacetic anhydride in pyridine: [9] Picrotoxin has also been used as a starting material in several synthetic processes, including the creation of dl -picrotoxadiene, which retains certain features of the picrotoxin skeleton.