Difluorooxymethylene-Bridged Liquid Crystals: A Novel Synthesis Based on the Oxidative Alkoxydifluorodesulfuration of Dithianylium Salts

Abstract

Insertion of a difluorooxymethylene bridge into the mesogenic core structure of phenylcyclohexane‐based liquid crystals results in a class of materials that exhibits a surprising and unprecedented improvement of essentially all application‐relevant properties (see scheme). A novel synthetic procedure allows the convenient large‐scale preparation of a variety of compounds based on α,α‐difluoroalkyl ether structures.

Single crystal X-ray structural features of aromatic compounds having a pentafluorosulfuranyl (SF5) functional group

“…In particular, compounds containing the trifluoromethyl (CF3) group or sulfurpentafluoride (SF5) group have a key role in organofluorine chemistry due to their special properties such as low surface energy, hydrophobicity, high chemical resistance, high thermal stability and electronegativity. Compounds containing fluorinated groups have been also used as materials, polymers and organic superconductors [13][14][15][16][17][18]. Although SF5 bearing aromatic compounds have been getting huge attention, their crystal structures have been sparsely reported.…”

Site directed synthesis of mono and disubstituted SF5-polyfluoroalkyl benzenes

“…The addition of SF 5 Br to the trifluorostyrenes proceeded fast with alkyl or halogen substituents ( p-CH 3 , o-CH(CH 3 ) 2 , o-F, m-Br, p-Br and p-Cl) and less readily with electron withdrawing substituents (o-CF 3 , p-CF 3 , p-NO 2 ). Similar reactivity patterns were found in the fluorination step.…”

“…Although a large body of work has been published with compounds containing perfluoroalkyl groups, only a small number of compounds containing an F 5 S-group or F 5 S(CF 2 ) n -groups have been prepared and investigated, even though useful properties ranging from the fields of liquid crystals to pesticides to dielectrics are enhanced by incorporation of the F 5 S-moiety [4]. The F 5 S-group as a polar terminal group has produced a new class of liquid crystals that have very strong dielectric anisotropy with some having monotropic nematic and smectic phases [5,6].…”

6.06 Synthesis of Fluorides

“…Nucleophilic fluorination of ester thioacetal with triethylamine-hydrogen fluoride in the presence of bromine can also be used synthesize α,α-difluorinated ethers (Scheme 19). 82 When carbonates are treated with SF 4 , bis(alkoxy) difluoromethane products are formed. 83 Benzyl alcohols treated with XeF 2 84 or aryl difluoro-λ 3 -bromane (Scheme 20) 85 undergo oxidative rearrangement through phenonium intermediates.…”