Study On Preparation Of Cyclic Di-p-xylyene And Its Chlorine Substituted Derivatives

Xylene polymer is a conformal protective polymer coating material, and has been widely applied in such fields as those of spaceflight and aviation, biomedical engineering. Cyclic di-p-xylyene and substituted derivatives thereof are the monomer of the preparation of xylene polymer. The preparation methods and conditions were studied in the paper.An method for synthesizing cyclic di-p-xylyene by Gorham was developed. The influences on the preparation technicwere described: include experimental device, reaction temperature, molar ratio of water vapour. The result show that the optimum conditions are n(water vapor):n(parylene)=150~200:l, reaction temperature 950℃～ 970℃. But because of the restrict of experimental conditions, the yield was not more than 10%. The structure of the product was characterized by means of IR spectroscopy and ~1HNMR. The melting point and density of the product were respectively 290℃, 1.22g/cm~3.An improved method for preparing quaternary ammomium salt using p-methyl-benzyl chloride and trimethylamine, preparing cyclic di-p-xylyene by Hofmann elimination was developed. The fluences of reaction temperature, reation time, etc., on the yield of two products were discussed. The result showed the optimum conditions for preparing quaternary ammomium salt were n(p-methyl-benzyl chloride): n(trimethylamine) =1:1.1, ethanol as solvent, reaction temperature 20℃ and reaction time 2h, and the yield were 94%. For cyclic di-p-xylyene, the optimum conditions are n(NaOH) : n(quaternary ammomium salt)=5:1, reaction temperature 110℃ , reaction time 7～9h, the yield of product wre 20%. The structure of the product was characterized by means of IR spectroscopy and ~1HNMR. The melting point and density of the product were respectively 286℃, 1.22g/cm~3.Based on these facts, a method for preparing the chlorine substituted derivative of cyclic di-p-xylyene was studied. The result showed that the reaction conditions were n (cyclic di-p-xylyene): n (chlorine) =1:2,(?).reaction temperature 20°C, carbon tetrachloride as solvent, iron powder reduced as catalyst. The structure of the product was characterized by means of IR spectroscopy and ~1HNMR. The melting point and...