The Synthesis Of New Chitosan-based Organotin Compounds And Their Molluscicidal Activity

Chitosan was modified through three chemical ways in this paper. The various kinds of chitosan organotin esters were synthesized by the reaction of modified chitosan with organotin compounds accordingly. The experiments of molluscicidal activity of various kinds of chitosan organotin esters were carded out.Main results as follows were gotten in this paper:Chitosan can be modified by CS₂ in the presence of base.The best conditions of xanthonation is that the concentration of NaOH is 35%and the alkalized time is ld.The dosage ration of chitosan and CS₂ is 1:4[weight(g)to volume(mL)]in the mixed solvents of methanol and water,and the best reaction temperatue is 55℃,the best reation time is 6h.Chitosan xanthogenate can adsorb Cu²⁺efficiently.The results show that the higher the degree of substitution,the better the adsorbing capacity. The optimum pH range of Cu²⁺adsorption is 6.0～7.0,the optimum adsorption temperature is 40℃,the optimum adsorption time is 0.5h.Under such conditions,the adsorbing content of DTC-CTS for Cu²⁺ is 349.5mg/g,and it is 7%more than that of CTS.Adsorbed Cu²⁺can be quantitatively eluted from DTC-CTS with 10%ammonia with the washed off rate of 96%.DTC-CTS can be used repeatedly three times and adsorbing content decline venially.Chitosan xanthogenate was swelled adequately in 90%CH₃OH,then methanol solution contained Ph₃SnCl were dropwised.Triphenyltin chitosan xanthogenate which doesn't dissolve in organic solvent and water was synthesized after two day's fast mixing and characterized by UV,IR,NMR,TG-DTA and X-ray diffraction methods etc.Phosphorylatedchitosan was synthesized by the reaction of monosodium orthophosphate with urea in the presence of HAc.The degree of substitution of phosphorylatedchitosan is 1.57 by acid-base titration.Three new kinds of compounds- triphenyltin phosphorlatedchitosan,tributyltin phosphorlatedchitosan and tribenzyltin phosphorlatedchitosan-were further prepared by the nucleophilic substitution reaction of chitosan phosphate with organotin in the presence of 85%CH₃OH.These compounds were characterized and analyzed by IR,NMR,TG-DTA and X-ray diffraction means etc.N-methylene phosphonic chitosan was synthesized by the reaction of chitosan with phosphoric acid and foermaldehyde in the presence of HAc. The degree of substitution of Phosphorylatedchitosan is 1.22 by elementary analysis.Three new kinds of compounds- N-methylene phosphonic chitosan triphenyltin ester,N-methylene phosphonic chitosan tributyltin ester and N-methylene phosphonic chitosan tribenzyltin ester-were further synthesized by the reaction of N-methylene phosphonic chitosan with organotin in the presence of benzene or toluene and characterized by IR,NMR,TG-DTA and X-ray.The experiments of molluscicidal activity show that molluscicidal activity of chitosan tributyltin ester is the most active.The oncomelania death rate is 100%when the concentration of the chitosan tributyltin ester reaches above 0.5mg/L and the soaking time is 24h.The molluscicidal activity of chitosan triphenyltin ester is like that of chitosan tribenzyltin ester.The oncomelania death rate is 100%when the concentration of those reaches above 0.5mg/L and the soaking time is 72h.