Ethers, Alcohols, Esters, Sulfides, and Selenides

An oxygen bound to a trifluoromethyl group has much less effect upon its chemical shift than a chlorine substituent. Thus, the fluorines of trifluoromethyl ethers (—58 ppm) are not as deshielded as those of CF3C1 (—28 ppm). Those of CF3 sulfides and selenides are deshielded still further (—42 and -37 ppm, respectively). Also, aryl and alkyl trifluoromethyl ethers have similar fluorine chemical shifts, as do aryl and alkyl trifluoromethyl sulfides. 

Because of the high reactivity of such compounds toward acyl substitution, CF3 carboxylate esters are rarely encountered. Nevertheless, 

Interestingly, the trifluoromethyl oxonium compound is deshielded relative to the analogous ether, whereas those of the sulfonium CF3 groups are actually shielded compared to the simple sulfides. 

Continuing the trend observed going from CH2F to CF2H to CF3 carbons, the 13 C chemical shift of a trifluoromethyl ether is actually more shielded (by about 5 ppm) than that of a trifluoromethyl hydrocarbon. 

The proton at carbon 2 appears as a septet at 4.14 ppm, which indicates that all of the three-bond couplings must be virtually the same (about 6 Hz). This includes the observed coupling of the OH proton, which appears as a doublet at 2.13 ppm. The CH3 protons also appear as a doublet at 1.40 ppm. 

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