Fluorinated Diethers

In addition to fluorinated linear diethers of 1,2-dimethoxyethane (DME) [6], fluorinated cyclic diethers such as 2,2-bis(trifluoromethyl)-l,3-dioxolane, 2,2-dimethyl-4,5-difluoro-1,3-dioxolane, and 2,2-dimethyl-4,4,5,5-tetrafluoro-1,3-dioxolane having low melting points were disclosed in a patent [52]. 

Physical and electrochemical properties of partially fluorinated l-ethoxy-2-methoxyethane (EME) and 1,2-diethoxyethane (DEE) derivatives such as 2-fluoroethoxymethoxy ethane (FEME), 2,2-difluoroethoxymethoxy ethane 

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The preparative-scale separation of enantiomers on chiral stationary phases (CSPs) by GC cannot match the overwhelming success achieved in the realm of liquid chromatography (LC) (Francotte, 1994, 1996 and 2001). Modern commercial instrumentation for preparative-scale GC is not readily available. In contrast to LC, separation factors a in enantioselective GC are usually small (a = 1.01 - 1.20). This is beneficial for fast analytical separations but detrimental to preparative-scale separations. Only in rare instances are large chiral separation factors (a > 1.5) observed in enantioselective GC. Only in one instance, a separation factor as high as a = 10 was detected in enantioselective GC for a chiral fluorinated diether and a modified 7-cyclodextrin (Schurig and Schmidt, 2003) (vide supra). 

Section 2.2 mainly reviews the papers on novel fluorinated organic solvents, which include fluorinated lactones, fluorinated linear carboxylates, fluorinated cyclic carbonates, fluorinated linear carbonates, fluorinated monoethers, fluorinated diethers, and others. The physicochemical properties of typical fluorinated compounds are summarized in comparison with nonfluorinated counterparts. 

Reaction in methanol yields the substituted diether 13 whereas, in methylene chloride, intramolecular cyclization to an ether cation takes place and attack by the nucleophilic F from the electrolyte yields a fluorinated cyclic ether 14 (cf also Reference 197). 

In the presence of an excess of potassium ethoxide, the ethoxide anion joins the less negative end of the double bond. Strong electron back-donating power of fluorine increases negativity at the carbon linked to chlorine and causes the addition of the ethoxide ion to the carbon linked to fluorine. Subsequent ejection of fluoride anion restores the double bond, and the final product is a diether, compound P [7/J. 

A Carboxylic add dialkylamides B Carboxylic add esters C Monopropyleneglycol esters D Glycerol acetals and ketals E Glycerol esters F Glycerol diethers G Glycerol triethers H Fluorinated glycerol diethers... 

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