Preparation Of Asymmetric Biphenyl Liquid Crystal And The Process Improvement Of Celecoxib

The structures of the liquid crystal core have much impact on the properties inthermotropic LC. Especially, the clear point is much higher and the physical andchemical performance is excellent when the structure of LC core with a biphenyl unit.Directly to the current biphenyl as a bridge bond centre to biphenyl syntheticelement with the liquid crystal monomer has not been reported. In this thesis, designand synthesis of novel rode-like crystalline monomers. The research not only enrichedthe study of crystal monomers, but also for our further synthetic liquid crystalpolymers and performance and application of research provides an important basis. Inthis thesis, the process research of celecoxib also was optimized which providesreliable technical parameters for the scale production of generic drug.In this thesis, four monomers M1~M4were synthesized, which include threecompounds centered methylene biphenyldiol, one asymmetric compound centeredbiphenyl. Biphenyl liquid crystals were prepared from3,3′,5,5′-tetramethyl-diphenoland1-brompentane by Williamson ether reaction, acylation, esterification.The structures and optical and thermodynamic properties of the obtained liquidcrystalline monomers were investigated by FT-IR spectroscopy, differential scanningcalorimetry (DSC), thermo gravimetric analyzer (TGA) and polarizing opticalmicroscopy (POM).Results of experiment and analyses indicated that the clearing point of M4wasobserved when heated to210.1℃. The classical nematic of liquid crystalline isbecoming brighter with the incline of temperature. The sample lose weight5%at351℃，this indicates that this compound have excellent thermal stability. Therefore, itmay have potential applied value.In later content of this thesis, the reaction time, solvent, temperature of celecoxiband crystallization process were screened, the optimized process conditions andindustrial process design were developed for scale production of celecoxib. Thedeveloped process decreased the cost of solvent significantly (partly in place ofethanol with water) and increased product quality for further industrial production.