General synthesis method of alkyl–alkoxy multi-fluorotolanes for negative high birefringence nematic mixtures

Convenient new methods for the synthesis of 4'-alkyl-, 4'-alkylcyclohexyl or 4'-alkylphenyl monofluoro-, difluoro- and tetrafluoro-substituted 4-alkoxy- or 4-alkyltolanes are proposed. The temperature and enthalpy of the phase transition for the homologues of the eight series, as well as the examples of the mixtures with negative dielectric anisotropy (Δϵ < −5) and high birefringence (Δn ≥ 0.3), are given.