Tri fluoroethanol

H2Br (bromoethanol) > —H2CH3 (propanol) > H2C1 (chloroethanol) > Fj (tri-fluoroethanol) > —H2F (fluoroethanol) > —H3 (ethanol)... 

Regarding proton spectra, as was the case with 2,2,2-trifluoroethyl chloride (Scheme 5.7), the chemical shifts of the CH2 protons of 2,2,2-tri-fluoroethanol and of 2,2,2-trifluoroethyl ethers are more affected by the OH or ether substituents than they are by the CF3 group. 

A catalytic asymmetric amination reaction has been developed using Cu(2+) catalysts (246). The azodicarboxylate derivative 392 reacts with enolsilanes in the presence of catalyst 269c to provide the adducts in high enantioselectivity, Eq. 213. As observed in the Mukaiyama Michael reactions, alcoholic addends proved competent in increasing the rate of this reaction. Indeed, in the presence of tri-fluoroethanol as additive, the reaction time decreases from 24 to 3 h. 

The alcoholysis rate decreases by either increasing the steric bulk of the alcohol or decreasing its nucleophUicity (i.e., MeOH > EtOH > PrOH > BuOH 2,2,2-tri-fluoroethanol). Parallel to the decrease of the chain-transfer rate, the molecular weight of the copolymer increases. An effective role of water as hydrolysis agent in alcoholic media appears very unlikely as HOOC-terminated polyketone or oligo-ketone have never been observed. Obviously, in neat water, hydrolysis is a feasible chain-transfer path, leading to acid-terminated materials [13]. 

A good example of the fact that a considerable number of fluorinated chemicals are not toxic per se, but elicit toxicity only after metabolic modifications, is the toxic behavior of tri-fluoroethanol and/or its derivatives, e.g. the anesthetic Fluoroxene (CF3CH2OCH = CH2)4 43 and analogs, 2.2,2-trifluoroethyl ethyl ether and others.44,45... 

Novotny found that neat trifluoroacetic acid could be hydrogenated to 2,2,2-tri-fluoroethanol in the presence of rhodium or iridium catalyst under much milder con-... 

Finally, in a recent paper DeLucca and Paquette have examined the solvolyses of several trimethylsilyl-substituted cyclopropylcarbinyl trifluoroacetates in 2,2,2-tri-fluoroethanol. This study was initiated to learn of the nature of trimethylsilyl substituent effects in cyclopropylcarbinyl systems. The kinetic results obtained are shown below... 

The triad distribution in the copolymer was found to be bernoullian and is accounted for by a one-parameter model therefore, chain end control of the stereochemistry was assumed [80]. For the systems based on bipyridine, no influence of the counter-ion on the stereochemistry of the produced copolymers was found however, the catalytic activity was highest with the weakest coordinating anion [81]. Bis-chelated complexes of 2,2 -bipyridine or 1,10-phenanthroline [ Pd(N-N)2 X2 ] were efficient catalyst precursors, particularly when used in 2,2,2-tri-fluoroethanol as the solvent [82] under these conditions stabilization of the catalytic system by an oxidant is unnecessary, and very high molecular weights were obtained [83]. 

A similar difference in coupling constants is shown by the nonequivalent methylene protons in the tetrahydropyranyl ether of tri-fluoroethanol (26). Non-equivalent ethyl and benzyl methylene... 

Acceleration of the reaction has been achieved by the use of the polar solvent tri-fluoroethanol and also by the addition of silver triflat thus, it can be assumed that cationic rhodium complexes act as the active catalyst. Eight-membered metallacycles such as 9 are probably key intermediates. [6] Cyclopropyl-substituted five-membered metallacycles 8 and homoallyl complexes 10 can be considered as precursors of 9 [7] (Scheme 4). 

Fqgure 2. Absorption spectra of (A) styrene radical cation in 2,2,2-tri-fluoroethanol (TFE), (B) p-melhyl tyrene radical cation in TFE, (C) 4-methoxystyrene radical cation in acetonitrile, arxl (D) a-rnethyl-4 meiboxystyrene radical cation in acetonitrile. Each radical cation was generated by 266 nnn laser irradiation of the correspoixling styrene. 

Various membranes of 2, 2, and nylon 6 were cast from the 5% solutions of the respective polymers in 2,2,2-tri-fluoroethanol-chloroform (1 1 wt.) mixture under the following different conditions ... 

Activated esters of halogenated alcohols such as 2-chloroethanol, 2,2,2-tri-fluoroethanol, and 2,2,2-trichloroethanol have often been used as substrate for enzymatic synthesis of esters, owing to the increase in the electrophilicity (reactivity) of the acyl carbonyl and to the need to avoid significant alcoholysis of the products by decreasing the nucleophihcity of the leaving alcohols [ 1 ]. 

Figure 4 Association of racemic sulfoxides and lactones with 2,2,2-trifluoro-1-phenyl ethanol [14] and 1-(9-anthryl)-2,2,2-tri-fluoroethanol [15].

Harmata et al. have applied their [4+3] cycloaddition/quasi-Favorskii rearrangement to several different classes of natural products. One of these are the sterpuranes, which are sesquiterpenes represented by sterpurene 103 (Scheme 19.27) [57]. Treatment of diene 97 with a shght stoichiometric excess of 2,5-dibromocyclopentanone 98 and triethylamine using tri-fluoroethanol and benzene as the solvent resulted in the formation of cycloadduct 99. This is a relatively rare example of an intermolecular [4+3] cycloaddition in which the diene is used stoichiometrically. Typically, the diene is used in excess relative to the ally lie cation precursor. Reduction of the ketone 99 with lithium aluminum hydride, followed by treatment with potassium hydride to effect the quasi-Favorskii rearrangement, gave aldehyde 101, presumably through intermediate 100. Reduction of aldehyde 101 gave alcohol 102 in 91% yield from ketone 99. Alcohol 102 was subsequently converted into sterpurene 103. 

The high solubility of the MTO catalyst in almost any solvent opens up the options for a broad spectrum of reaction media to choose from when performing epoxida-tions. The most commonly used solvent, however, is stiU dichloromethane. From an environmental point of view this is certainly not the most appropriate solvent in large scale epoxidations. Interesting solvent effects for the MTO-catalyzed epoxida-tion were reported by Sheldon and coworkers, who performed the reaction in tri-fluoroethanol [77]. The change from dichoromethane to the fluorinated alcohol allowed for a further reduction of the catalyst loading down to 0.1 mol%, even for terminal alkene substrates. It should be pointed out that this protocol does require 60% aqueous hydrogen peroxide for efficient epoxidations. 

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