Synthesis And Characterization Of Retinyl Schiff Base

Retinyl Schiff base salts will be developed to an important kind of new materials for stealth and electromagnetic protection for their ability of wave absorption. In this paper, several kinds of retinyl Schiff base salts were synthesized and characterized.The retinal was prepared by selective oxidation under existence of a mixture oxidizer (CrO₃·R₁R₂NH₂·HX) from vitamin-A that was obtained by phase transfer catalytical hydrolysis of vitamin-A acetate.The retinyl Schiff base was synthesized by retinal and di-amine, and the retinyl Schiff base salt was prepared by dripping the solution of FeCl₃ in alcohol to the product of retinyl Schiff base and di-amine. The elemental analysis and IR spectra were used to confirm the samples' structure. The electromagnetic parameters were tested, and the reflectivity curves of the samples were simulated, which gave the results that retinyl Schiff base ethylene di-amine and retinyl Schiff base p-phenylene di-amine had reflectivities of -9dB in the frequency of 13GHz～14GHz and -10dB in the frequency of 11GHz～12GHz, respectively.Poly-p-phenylene terephthamide (PPTA) with end groups of primary amine and viscosity average molecular weight of about 800 was prepared by reaction of p-phenylene diamine (PDA) with terephthaloyl chloride (TPC) under the conditions of -10℃and excessive usage of PDA. Polymeric structured retinyl schiff base was synthesized from the as-prepared retinal and PPTA, and the structures of the products were characterized by elemental analysis, FT-IR, thermal analysis, etc. The results showed that the product was the designed retinyl Schiff base, and the temperature of heat decomposition is 340℃. The electromagnetic parameters were tested, and the reflectivity curves of the samples were simulated, which demonstratedthat the retinyl Schiff base polyamide appeared worse effect of microwaveabsorption than that of retinyl Schiff base ethylene di-amine and retinylSchiff base p-phenylene di-amine.