Development Of Diphenol Products And Study On Synthesis Of Biphenyl Liquid Crystals

3,3′,5,5′-tetramethyl-diphenol(TMBP) is an important organic intermediate of dye which can be used as modified monomers of polyester, polyurethane, polycarbonate, polysulphone, epoxy resin and so on. Also used for the stabilizer of rubber, emulsion, plastic and some petroleum products. This experiment provided a new synthetic route of TMBP. It was synthesized from 2,6-dimethylphenol by two-step method which are oxidative coupling and reduction reaction, hydrogen peroxide was used as oxidant in the water. The effect of oxidant and catalyst on product was studied, The optimum process was determined and was that 2, 6-dimethylphenol: oxydol: catalyst= 1: 2: 0.00018 (molar ratio), the temperature and time of oxidative coupling are 80℃and 3h, the temperature and time of reduction reaction are 80℃and 0.5h, the yield and purity are above 80% and 99% respectively. The method is very useful from the industrial point of view.Epoxy resin containing biphenyl structure is a kind of liquid crystal epoxy resin. 3,3′,5,5′-tetramethyl-4,4′-di(2-hydroxyethanyoxy)-biphenyl as a modified monomer of epoxy resin was synthesized by a new synthesis method in this article. Also 3,3′,5,5′-tetramethyl- diphenyldiglycidyl ether was synthesized by three methods. Reaction steps, raw material, reaction conditions, yield and treatment processes of three methods were studied. Then two epoxy resins containing biphenyl structure were synthesized, They are 4,4′-bis(2-hydroxylethyl)-3,3′,5,5′-tetramethylbiphenyl(BP1) and 4, 4′-bis( 4-hydroxybenzoyloxy ) -3,3′,5,5′-tetramethylbiphenyl (BP2).At present biphenyl liquid crystals are widely used. Eight symmetrical diphenylnate liquid crystals were prepared from 3,3′,5,5′-tetramethyl-diphenol in this article. Their liquid crystal properties were tested by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and hot stage polarizing microscop (POM). The crystal structure ofâ…¢a was detemfined by single crystal X-ray diffraction techniques,â…¢a is a monoclinic crystal system, space group P2₁/C with the unit cell parameters: a=18.525(3)(A|°), b=12.196(2)(A|°), c=12.195(2)(A|°),(A|°)=97.142(2)°, V=2733.7(9)(A|°)³, Z=4, D_c=1.163 Mg/m³, R=0.0521, R_W=0.1161. The results showed that molecules lead thermotropic liquid crystals properties. The relations among the mesomorphism, oxygen atoms, terminal unsaturated bond, the flexible chain length were investigated.