TRI FLUOROMETHANE

The aldol reactions introduced thus far have been performed under basic conditions where enolate species are involved as the reactive intermediate. In contrast to the commonly accepted carbon-anion chemistry, Mukaiyama developed another practical method in which enol species can be used as the key intermediates. He is the first chemist to successfully demonstrate that acid-catalyzed aldol reactions using Lewis acid (such as TiCU) and silyl enol ether as a stable enol equivalent can work as well.17 Furthermore, he developed the boron tri-fluoromethane sulfonate (triflate)-mediated aldol reactions via the formation of formyl enol ethers. 

The enhancement in the receptor capacity to host anions has been successfully achieved by the design of double-cavity ligands. This is reflected in the conductometric titration curve (Fig. 4c) for the fluoride anion when titrated with receptor 7. In fact, in A/,A/-dimethylformamide, this receptor takes up two anions per unit of ligand while discriminating against other spherical (chloride, bromide and iodide) and non-spherical (hydrogen sulphate, perchlorate, nitrate and tri-fluoromethane sulphonate) anions except H2POj. With this anion only the formation of a 1 1 complex was observed. 

Excess trifluoroiodomethane (2mL) was condensed into a 5-mL flask containing (EtO)3P (I 1.93 g, 12 mmol, freshly distilled from Na metal). The mixture was irradiated for 10 h with a Black-Ray Long Wavelength Ultraviolet source (350.0 nin). After evaporation of unreacted trifluoroiodomethane and tri-fluoromethane byproduct, distillation of the remaining residue gave diethyl trifluoromethyl phosphonate (5) yield 1.2 g (51 %) bp 65-67.5 C/8 Torr. 

The continuous photochemical decomposition of trifluoroacetaldehyde closely resembles that of acetaldehyde, the main products at A 3130 A being tri-fluoromethane and carbon monoxide. A chain reaction involving trifluoromethyl radicals is probably involved... 

CgHeNeOfi mw 258.18 N 32.56% OB to COj —55.78% It yel triclinic cryst mp, not fixed, however, instantaneous hot-bar decompn temp is 450—51° (thermal decompn is rapid above 320°) d 1.93 0.0/g/cc (cryst observed), 1.937 g/cc (calcd from X-ray data). > 20% wt/vol sol in superacids such as coned sulfuric acid, chlorosulfonic acid, fluorosulfonic acid and tri-fluoromethane sulfonic acid Ml.1% wt/vol sol in solvents such as aniline, dimethylformamide, phenylhydrazine, ethylenediamine, gammabutyro-lactone and NB insol in benz, chlf, ethanol, eth, and gl acetic acid (Refs 6,9,12, 34, 56 and 66). 

The flammability of halogenated hydrocarbons shows wide variation. While compounds such as carbon tettachloride and chloroform are noncombustible liquids, there are substances such as Halons which are used for fire-extinguishing purposes. Several low-molecular-weight halocarbons are flammable gases or liquids. Many Ci and C2 fluorocarbons are flammable gases. These include tri-fluoromethane [75-46-7], 1,1-difluoroethane [75-37-6], chlorodifluoroethane [25497-29-4], chlorotrifluoroethylene [79-38-9],... 

All 1,3-dialkylimidazolium ILs reported to date are hygroscopic, and their miscibility with water is largely controlled by the nature of the anion. While those salts containing the nitrate, chloride and perchlorate anions are usually miscible with water in all proportions, those associated with hexafluorophosphate and bis(tri-fluoromethane) sulfonylamidate anions are almost completely immiscible with water [93]. Interestingly, the miscibility with water of those containing the tetraf lu-oroborate anion is temperature dependent (Fig. 3.5-7) [36]. It is also known that an increase of the N-alkyl chain lengths increases the hydrophobicity for a series of 1-alkyl-3-methylimidazolium hexafluorophosphate ILs [94] The miscibility of water with ILs can be increased by the addition of short-chain alcohols [95] or diminished by the addihon of salts (salting-out effect) [96]. 

K Akao, Y Yoshimura. Keto-enol tautomeric equilibrium of acetylacetone in tri-fluoromethane near the critical temperature. J Chem Phys 94 5243, 1991. 

Around the same time, the photocatalytic trifluoromethylation of electron-rich heteroarenes such as indole, furan, pyrrole, and thiophene using CF3I as the tri-fluoromethane source was reported by Cho and coworkers (Eq. (13.24)) [66b]. 

Treatment of sulfoxide 20 with Me2SiCl2 and alcohols a-f gave the mixed silyl acetals 21a-21f in good yields (Scheme 7). Activation of the sulfoxide with tri-fluoromethane sulfonic acid anhydride (TfjO) and base, presumably resulting in the five-membered intermediates 22a-22f responsible for exclusive glycosidation at the P face, gave P-mannopyranosides 23a-23f. 

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