Abstract:

3-Butenyl-based liquid crystals are a new series of liquid crystals with low melting point and high clearing point. A new synthetic method for key intermediate aryl boric acid was improved via Arbuzov, Wittig-Horner, catalytic hydrogenation and lithiation-boric acid 4-step reactions by using 3-fluorobenzyl chloride as the starting material. Isomerization of trans-cyclohexane and defluorination side reactions were avoided. After optimization the total yield was improved from 4.5% to 30%, which is valuable for industrial production. Physical properties test indicates that the new compounds have virtual clearing point of 127.7 ℃ and a large splay elastic constant K₁₁ value of 19.7. Transmittance-voltage test shows that the compound can shorten the total response time by 10%, which coincides with its low elastic-viscosity value. The new 3-butenyl-based liquid crystals have potential applications in developing high performance liquid crystal mixtures.

Key words: fluorinated liquid crystal, butenyl group, synthesis, property