The Synthesis Of Liquid Crystals Containing Fluorine

Using Suzuki cross coupling reaction and Wittig reaction a series of biaryl type liquid crystal containing fluorine and ethane type liquid crystal containing fluorine were synthesized.A series of biaryl type liquid crystal containing fluorine were synthesized from halo-Aromatic compounds and phenylboronic acid containing fluorine with a new type catalysis—Pd(Pph₂COO)₂.The optimal experimental conditions were investigated. The experiments demonstrated that the suitable operation conditions are toluene and water as the reaction solvent with 1:1.4:3:0.1:0.005 mole ratio of halo-Aromatic, phenylboronic acid , K₂CO₃,N (n-bu)₄Br, Pd(Pph₂COO)₂ for 4 hours at 80-90℃, The yield of cross-coupling of aryl bromides with arylboronic acid was about 98 %. The experiments demonstrated that Pd(Pph₂COO)₂ has good catalysis ability. The cause of the catalyst decomposition and appearance of Palladium black were studied. The activity of freshly prepared catalyst was stable after being repeatedly used for 3 times. The results of DSC show that these liquid crystal compounds exhibit broad temperature range of mesomorphic phases and high clear points.A kind of new synthesis route was invented. Cyclohexnone and methoxymethyltriphenyl phosphonium chloride as start materials, A series of ethane type liquid crystal containing fluorine were synthesized by Wittig reaction ,hydrolization,isomerization,Wittig reaction and then hydrogenation reaction, The experiments demonstrated that at 0-10℃, t-BuOK as the base, the yield of Wittig reaction was about 90%.The liquid crystals that have synthesized are favorable to materials for thin film transistor (TFT)-addressed twisted nematic (TN) liquid crystals display.