Borohydride Exchange Resin Is Applied In Preparation Of Liquid Crystal Material

Liquid crystal is a kind of electronic optical organic material. It acted a very important role in modern display field. It is an important intermediate which contain hydroxyl group in liquid crystal molecule. Many crystal compounds which have excellent behavior have been synthesized from hydroxyl containing intermediate. It has a limitation, although the synthetic methods have been developed for long ages. Liquid crystal of tolan-type compounds can be synthesized from hydroxyl intermediate, while exhibits good optical, enthusiastic and chemical stability, and has wide application. At the same time, it is also used for improving birefringence and clearing point of the liquid crystal mixture, for descending viscosity and rising response time of the liquid crystal mixture. Therefore, the synthesis of tolan liquid crystal compound has a great practical value.The thesis consists of two chapters, and the main contents are as follows:1. Carbonyl group, ester and carboxyl compounds are reduced by Polymer-supported borohydride anion exchange resin, Hydroxyl intermediate of liquid crystal were synthesized. The purity of all these compounds was tested by GC, and their structures of the title compounds were identified by MS, IR and ~1H NMR. Reaction conditions were optimized based on these facts. Experiment showed that carbonyl and ester compounds can be reduced by BER, the reaction is available in protic solvent; the speed of the reaction increased and the yield improved with the raise of reaction temperature; carbonyl compound were reduced easier than ester compound, the higher yield of ester compound can be reached with more reducing agent; carboxyl compounds can not be reduced by the system of BER/ katalyst. Besides, steric hindrance influenced the reaction greatly, reaction were harder with increase of the substituted group.2. 4-(propylcyclohexyl)- 4' -methyl tolan-type were synthesized by a method consisting of six steps: reducing reaction, chloride replaced, elimination HCl, bromic addition, elimination and palladium-catalysed Sonogashira cross-coupling reaction. The purities of all these compounds were tested by GC, and their structures of the title compounds and important intermediates were identified by MS, IR and ~1H NMR. The results are consistence to each other. Their reaction conditions and synthetic methods were discussed as well.