Synthesis of internal fluorinated alkenes via facile aryloxylation of substituted phenols with aryl trifluorovinyl ethers

Abstract

Nucleophilic addition-elimination of ortho- or para-substituted phenols to aryl trifluorovinyl ethers (TFVEs) in N,N-dimethylformamide was studied. Using sodium hydride as a base afforded vinyl substitution products R-Ar-O-CF=CF-O-Ar-R', where R or R' = H, Br, OMe, tert-Bu, or Ph. The vinyl substitution products produced mixtures of (Z)/(E)-isomers and this isomer ratio was influenced by substitution with more sterically encumbered phenol nucleophiles. Reactions using caesium carbonate afforded addition products R-Ar-O-CHFCF(2)-O-Ar-R' whereas upon dehydrofluorination using sodium hydride produced vinyl substitution products. The preparation of vinyl substituted and addition products proceeded in overall good isolated yields and were elucidated using (1)H and (19)F NMR, GC-MS, and X-ray analysis. Vinyl substituted products were inert to UV light and chemical reactivity using common polymerization promoters. Thermal activation of the (Z)/(E)-fluoroolefin (-CF=CF-) was observed at an onset of 310 °C in nitrogen using differential scanning calorimetry (DSC) producing insoluble network material. The synthesis, characterization, and mechanism for stereoselectivity are discussed.

Synthesis, Characterization, and Properties of New Fluorosilicone Block Copolymers

“…Figure 3 illustrates an example 19 F NMR of the conversion from the AMX dd-pattern from the aryl TFVE to broadened signals at -82.4 ppm (−CHFCF 2 −) and −140.7 ppm (−CHFCF 2 −) with the PFCB ring intact with a range of multiplicity at −128.7−(−131.9). These results are consistent with small molecule model studies on the investigation of the addition mechanism (17). 1 This optimized methodology was employed for the attempted preparation of the larger PFCB aryl ether block copolymer CS1K-b-PFCB16K as well as subsequent siloxane-extended copolymers CS5K-b-PFCB8K, CS5K-b-PFCB16K, CS10K-b-PFCB8K, and CS10K-b-PFCB16K.…”

AB-type monomers for the preparation of perfluorocycloalkene (PFCA) aryl ether polymers

“…The product distribution observed from the nucleophilic vinylic substitution of TFVE compounds and other fluoro-olefins suggests the formation of a short-lived fluorocarbanion intermediate [42]. A general mechanism for the nucleophilic vinylic substitution of TFVE compounds is shown in Fig.…”

Facile method towards functionalization of partially fluorinated polyarylethers via sequential post-polymerization modification

“…1.3:1 (Z)/(E)-isomers) and 1,2,2-hydrofluoroethane (CHFCF 2 ) groups on the backbone. The polymers produced using NaH as a base primarily possess CF = CF groups on the polymer backbone through an addition-elimination mechanism [42]. When Cs 2 CO 3 was used, the resulting FAVE polymers primarily possess CHFCF 2 groups on the polymer backbone though an addition mechanism.…”

“…The network polymer can be formed via thermal [2 + 2] cycloaddition reaction between aryl TFVE groups at relatively low temperature (N120°C) without requiring any catalyst and no by-products produced [53]. The aromatic TFVE group also can readily react with various nucleophiles (phenols and amines) through addition or addition-elimination processes under very mild conditions, which can be used to introduce functional groups into polymers [42]. The introduction of the TFVE group onto the side chain of the FAVE polymer was readily accomplished by DCC coupling of alcohol containing FAVE polymer P3 with commercially available p-(trifluorovinyloxy) benzoic acid.…”