Trifluoroacetone, reaction

Fluoroolefins may he prepared by the reaction of Wittig reagents and other pho sphorus-containtng y tides with fluorinated carbonyl compounds. (A discussion of the fluorinated Wittig reagents or other fluonnated phosphorus reagents with nonfluorinated carbonyl compounds is on page 581.) Tnphenylphosphoranes, derived from alkyltriphenyl phosphonium salts, react with 1,1,1-trifluoroacetone [3/] or other trifluoromethyl ketones [32, iJ] (equation 26) (Table 10). 

Other ketones besides acetone can be used for in situ generation of dioxi-ranes by reaction with peroxysulfate or another suitable peroxide. More electrophilic ketones give more reactive dioxiranes. 3-Methyl-3-trifluoromethyldioxirane is a more reactive analog of DMDO.99 This reagent, which is generated in situ from 1,1,1-trifluoroacetone, can oxidize less reactive compounds such as methyl cinnamate. 

In their original paper, Sieger and Calvert proposed the second of these routes as the predominant primary step. This is unlikely to be the case because no trace of products which could arise by the reactions of the trifluoroacetyl radical have been observed in the photolysis of either trifluoro- or hexafluoroacetone and it is assumed that this radical is unstable. In support of this is the evidence that the yield of ethane rises steadily with increase in temperature whereas that of hexafluoroethane remains approximately constant. Finally, in a recent re-investigation, Dawidowicz and Patrick49 have identified biacetyl in the products of the photolysis of trifluoroacetone. The most probable primary step is, therefore, the former, which provided the acetyl radical and a trifluoro-methyl radical. 

Smith and Calvert54 have provided evidence that at high temperatures, the photodecomposition of trifluoroacetone proceeds by a chain mechanism in which an alkyl radical is added to the ketone, the adduct then decomposing to form an ethane and a further radical. No satisfactory reaction scheme was advanced and an ingenious attempt to investigate the process by photolyzing mixtures of trifluoroacetone and 1,1,1-trifluoroacetophenone provided equivocal results. 

Organoaluminum reagents, 202 1,1,1-Trifluoroacetone, 323 Trityllithium, 338 Zinc chloride, 349 Stereoselective aldol reactions With boron enolates Boron trichloride, 43 Chlorodimethoxyborane, 73 9-(Phenylseleno)-9-borabicyclo-[3.3.1]nonane, 245 With silyl enol ethers... 

Ketones can be converted to dioxiranes by Oxone (2KHSO5 KHSO4 K2SO4) under shghtly alkaline conditions (pH 7-8) (400). The dioxirane of 1,1,1-trifluoroacetone is a powerful yet selective oxidant under mild conditions, typically at temperatures below 313 K (10). Exemplary reactions are stereospecific olefin epoxidation and hydroxylation of tertiary C-H groups, or ketonization of CH2 groups. With chiral ketones, even enantioselective reactions are possible (401). Although the reactions are often performed in excess ketone, it is actually possible to use the ketone in a catalytic fashion, for example, for 1,1,1-trifluoroacetone (Scheme 5). 

In a thermal reaction hexafluoroacetone [65] and several trifluoroacetones [66] also react with butadienes in a straightforward fashion. 

The probable mechanism of the reaction is first addition of piperidine to formaldehyde to form /V-hydroxymethylpiperidine. This reacts with acidic hydrogens of the methyl group of 1,1,1-trifluoroacetone, which is hydrated because the trifluoromethyl group next to carbonyl stabilizes the hydrated form of the carbonyl compound. The resulting dihydrate is further stabilized by hydrogen bonds to the piperidine nitrogen 103. ... 

Recently, Mello et al. have disclosed a simple and robust protocol for the generation of methyl(trifluoromethyl)-dioxirane from an aqueous solution of 1,1,1-trifluoroacetone hydrate, sodium bicarbonate, and peroxomonosulfate on a preparative scale (typically <2 g the authors suggest multiple iterations for larger scales). The methyl(trifluoro-methyl)dioxirane is removed from the reaction mixture by the evolved gases (O2, CO2) and has been applied to the oxidation of substrates in a second reaction zone (e.g., the epoxidation of cyclohexenone Scheme 33) <2007S47>. 

Sieger and Calvert originally favoured the latter of these as the predominant primary step, but the more recent study of the photolysis by Dawidowicz and Patrick indicates the former as the predominant step, in view of the identification of biacetyl among the products. Some complications in the mechanism are evident from the presence also of acetone, 2,2-difluoropropane, and a dimer of trifluoroacetone in the reaction products. The possibility of a chain reaction at high temperature has been discussed ... 

The primary act for the photochemical decomposition of trifluoroacetophenone (ref. 589) at A 3130 A is believed to be predominantly of Type 1, with the formation of benzoyl and trifluoromethyl radicals. On the other hand, a primary act of Type 2 has been proposed by Pritchard and Thommarson for the photolysis of hepta-fluoropropyl ethyl ketone. Studies on the photolysis of these and other fluorinated ketones showed many features in common with that of trifluoroacetone, but have also led to some interesting observations on radical-radical interactions. For example, Pritchard et identified the following reactions (leading to the formation of vinyl fluoride) during the photolysis of 1,3-difluoroacetone... 

The thermal decomposition of 1,1,1,-trifluoroacetone has been studied by Fekete - , and that of fluoroacetone hemiacetal esters by Newallis et Lewis and Newman have reported on the rearrangements of fluoroesters in the gas phase. Thermal reactions of nitrogen-containing fluoro-compounds have included trifluoromethyl cyanide , hexafluoroazomethane , tetrafluorohydra-zine , fluorodiazirines , perfluoropyridazines , fluorochlorodinitrometh-ane and poly(difluoroamino)fluoromethanes - . ... 

Smith, J. O., Mandai, B. K., Fiiier, R., Beery, J. W. Reaction of ethyi 4,4,4-trifiuoroacetoacetate enoiate with 3-bromo,1,1,1-trifluoroacetone ... 

The extraction of Pa(IV) by benzoylacetone (HBA) from perchloric acid and sodium perchlorate was investigated in a recent study of the equilibria in diketone extraction. The indicated reaction is reported to be the same as that given in Eq. (8), where M = PaO or Pa(0H) + (79). Diketones have also been used in the study of aqueous complexation. Oxalate (80), sulfate, and fluoride complexing of Np(IV), Pu(IV) and Th(IV) have been studied by thenoyl trifluoroacetone (TTA) extraction. The Dj is always higher when TTA is dissolved in benzene than when it is dissolved in ii-hexane (81), which is contrary to the usual observation of higher D s in aliphatic diluents. 

Activation. Hexafluoro-2-propanol, trifluoroacetone, and chiral arenesulfo-nimidoylimidazoles represented by 1 are useful activators of HjOj for oxidation of sulfides, epoxidation of allylic alcohols, and some other reactions. 

Hz) have been isolated, including octahedral Co(R R C=N—NHCOR )X2 (R = H, Me, or C5H10 R = Ph, p-MeOPh, or Me R = Ph, o-HOPh, or p-MeOPh X = NO3, Cl, Br, or SCN) and dimeric five-co-ordinate Co(R R C= NN=C0R )2- Formation constants have been reported for reactions between M bipy (M = Co, Ni, or Cu) and monoanions of the ) -diketonates acac, benzoyl-acetone, dibenzoylmethane and dipivaloylmethane. Cobalt ions have been extracted from an ion exchange resin by formation of Co(tta)2Bn (Htta = 2-thenoyl-trifluoroacetone, B = py base) and the synergistic effect decreased in the order py > > y-pic > a-pic > y-colidine isoquinoline > piperidine > 4-benzoyl-... 

The only example of an N-sulfonyl ketimine participating in an ene reaction involves the tosyl imine of trifluoroacetone 266 [90] [Eq.(62)]. When heated with a terminal olefin such as allyl benzene (265) in refluxing xylene, imine 266 leads to ene product 267 in moderate yields. However, internal alkenes gave significantly lower yields of ene products. The inefficiency of the ene process with more highly substituted olefins was ascribed to unfavorable steric effects due to the bulky trifluoromethyl groups. Interestingly, with /J-methyl styrene and allyl thiophenyl ether, [2+2]-cycloadducts were detected rather than ene products. 

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