- REACTIONS OF BROMORTRIFLUOROMETHANE WITH ACID DERIVATIVES IN THE PRESENCE OF ZINC.
-
Reaction of zinc with bromotrifluoromethane in pyridine gives poorly reactive trifluoromethyl zinc derivatives in the presence of ethyl benzoate whereas the Barbier condensation occurs with activated esters, like ethyl trifluoroacetate or ethyl oxalate, and cyclic anhydrides.
- Francese, C.,Tordeux, M.,Wakselman, C.
-
-
Read Online
- Practical Processes for Producing Fluorinated alpha-Ketocarboxylic Esters and Analogues Thereof
-
It is possible to produce a fluorine-containing α-ketocarboxylic ester hydrate by reacting a fluorine-containing α-hydroxycarboxylic ester with sodium hypochlorite or calcium hypochlorite of 21 mass % or greater in mass percentage of composition. Furthermore, it is possible to produce a fluorine-containing α-ketocarboxylic ester by reacting the hydrate with a dehydrating agent. Furthermore, it is possible to produce a fluorine-containing α-ketocarboxylic ester hemiketal by reacting the fluorine-containing α-ketocarboxylic ester hydrate with a lower alcohol or a trialkyl orthocarboxylate. Moreover, it is possible to produce a fluorine-containing α-ketocarboxylic ester by reacting the hemiketal with a dealcoholization agent.
- -
-
Paragraph 0143; 0144; 0145; 0146; 0147; 0148; 0149; 0150
(2018/03/10)
-
- Synthesis of fluorinated 1,2,3-butatrienes from α-halovinyl organometallic reagents
-
The thermal stability and dimerization reaction of fluorinated α-halovinyl zinc and copper reagents, RR'C=CYM (Y = F, Cl, Br; M = ZnX, Cu), have been explored in detail. Dimerization of these vinyl carbenoids to betatrienes occurred when R was an aromatic (C6H5 or C6F5) and R' was a perfluoroalkyl group (CF3, C2F5, C3F7). The role of the α-halogen was determined; the α-F vinyl copper reagent (R = C6H5, R' = CF3) decomposed by oxidative dimerization to 1,3-dienes while the α-Br and -Cl copper reagents dimerized to butatrienes. The fluorinated butatrienes prepared in this study, (E)- and (Z)-R1R2C==C=C=CR1R2 (R1 = CF3, R2 = C6H5; R1 = C2F5, R2 = C6H5; R1 = n-C3F7, R2 = C6H5; R1 = CF3, R2 = C6F5) are available on a multigram scale and readily obtained with high isomeric purity. The geometry of one member of each isomeric pair of butatrienes was characterized by X-ray crystallography. The mechanism of the dimerization reaction has been determined to be a nucleophilic displacement/β-elimination process. Diels-Alder (1,2-addition), bromination (1,2-addition), and isomerizatioa reactions are described.
- Morken,Bachand, Patrick C.,Swenson, Dale C.,Burton, Donald J.
-
p. 5430 - 5439
(2007/10/02)
-
- Reactions of Trifluoromethyl Bromide and Related Halides: Part 9. Comparison between Additions to Carbonyl Compounds, Enamines, and Sulphur Dioxide in the Presence of Zinc
-
A Barbier procedure, under moderate pressure, was used for the trifluoromethylation of various carbonyl compounds, starting from trifluoromethyl bromide and zinc in pyridine.Trifluoromethyl methanols were obtained from aldehydes and trifluoromethyl ketones from activated esters.Ethyl benzoate, or acetone, induced the formation of the solvated trifluoromethylzinc derivatives which did not react with carbonyl cpompounds.Consequently, the Barbier condensation in that case was considered to involve nascent organometallics reacting near the zinc surface.The reaction with sulphur dioxide, leading to trifluoromethanesulphinate, showed striking differences from that of carbonyl compounds.It was shown that the main pathway occcured in solution.This condensation was interpreted by the initial formation of sulphur dioxide radical anion, which reacts with trifluoromethyl bromide by a single-electron-transfer process.Attempts to condense iminium salts failed when a hydrogen atom was lacking in the α position.When the iminium ion can be transformed in situ to an enamine, a reaction occured, leading to α-trifluoromethyl ketones.This condensation was interpreted by a chain mechanism involving trifluoromethyl radicals.
- Tordeux, Marc,Francese, Catherine,Wakselman, Claude
-
p. 1951 - 1957
(2007/10/02)
-
- Process for the preparation of perfluoroalkyl ketones
-
A process for the preparation of a perfluoroalkyl ketone. A perfluoroalkyl halide, zinc and an ester are brought into contact with one another. Preferably a polar aprotic solvent and/or a pyridine is also present.
- -
-
-
- Catalytic Conversion of Fluoroalkyl Alkyl Ethers to Carbonyl Compounds
-
Fluoroalkyl alkyl ethers are generally available by attack of alkoxide ion on fluoro olefins.In the presence of Lewis acid catalysts, such methyl and ethyl ethers have now been found to lose methyl or ethyl fluoride, respectively, to give fluorinated carbonyl compounds.The carbonyl compounds include acid fluoride, ketone, keto ester, vinyl ketone, acyl ketene, ketene, and acryloyl fluoride.
- England, David C.
-
p. 4007 - 4008
(2007/10/02)
-
- Preparation of fluorocarbonyl compounds
-
Fluorinated carbonyl compounds are prepared by contacting a fluorinated methyl or ethyl ether containing at least one methoxylated carbon atom-containing group selected from: --CF2 OR3, =CFOR3, STR1 wherein R3 is CH3 or C2 H5, with a catalyst selected from: SbX5, TaX5, NbX5, AsX5, BiX5, TiX4, ZrX4, HfX4, FeX3, mixtures of SbX3 and SbX5, ZM'X'6, and mixtures of ZM'X'6 and M'X5 where X, independently, is F, Cl, Br or I, X' is F or Cl; and Z is H, NO, O2, alkali metal or NY4 where Y, independently, is H or alkyl of 1 to 6 carbon atoms, and M' is Sb or As at a temperature of -20° to 200° C.
- -
-
-
