Parallel Synthesis of 4-alkyl-4'-cyanobiphenyl Liquid Crystals

Abstract

In the search for novel nematic liquid crystal materials for display applications, it is common to investigate several different alkyl chain homologues of a particular core structure. It is sometimes possible to develop a synthetic pathway that allows homologous variation in the ultimate step, but the majority of published methods for liquid crystal synthesis begin from an alkyl chain containing intermediate. This results in a separate pathway for each homologue. A “one-pot” technique has been developed for the parallel synthesis of up to five homologues of a given core structure, exemplified by “the 4-alkyl-4′-cyanobiphenyl series, together with their isolation in gram quantities and high purity by preparative high performance liquid chromatography. The technique demonstrates that it is possible to identify and monitor each intermediate throughout the synthetic pathway, using gas chromatography/mass spectrometry. It is also shown that there are no substantive losses in yield for any homologue throughout the pathway. It is concluded that this technique is a viable method for the synthesis of novel liquid crystal materials.