Study On The Synthesis Of Chitosan Derivatives And Their Properties

With increasing environmental pollution, the wide use of synthetic polymeric materials gives advantages of great convenience and benefits. However, their difficult biodegradability causes great destruction to our survival environment. Chitosan's merits of good enviromental compatibility, renewability, rich resources, and low cost make it under observation. The paper describes the development of chitosan and its derivatives, researching state, and application. The paper also provides methods of modification or derivation for magnifing the applied scope of functional chitosan material.The main contents and conclusions are described as follows: (1) The crosslinked chitosan grafted by 4' -formal benzo-15-crown-5 obtained crosslinked chitosan with 4'-formal benzo-15-crown-5 (CCTS-N=CH-B-15-C-5) . Then it was loaded with palldium chloride to gain the heterogeneous catalyst, which was easily isolated from the reaction system. The influences of the Pd content of the catalyst, solvent, and temperature on asymmetric hydrogenation of α -phenylethanone have been studied. The catalyst has been found to catalyze the hydrogenation of α -phenylethanone into the chiral alcohol, α -phenyl ethanol under the mild condition. The optical yield of (R)-l-phenylethanol could be obtained in 97.1 % on the following conditions: temperature, 30°C; solvent, ethanol; Pd content, 1.43 mmol/g; substrate concentration, 0.02 g·mL^-1 thanks to cooperative effect of crown ether and chitosan polymer. The stability of this catalyst was also studied at the same time. This chiral natural crosslinked chitosan-palladium complex catalyst could be reused without appreciable change in optical catalytic activity, which will be useful for designing crosslinked-chitosan-based adsorption for metal ions for asymmetric hydrogenation.(2)New di-Schiff base type crown ethers crosslinked chitosan (CCTS-1) was synthesized by the reaction of 4, 4'-diformyldibenzo-18-c-6 crown ether with crosslinked chitosan. New di-secondary amine type crown ethers crosslinked chitosan(CCTS-2) was prepared by the reaction between CCTS-1 and sodium borohydride. Their structures were confirmed by Fourier transform infrared spectral analysis, X-ray powder diffraction analysis and elemental analysis. The adsorption rates by CCTS-2 for Ag+ for 1 h were 96% at pH 6.0, Ag+ initial concentration 0.5 mmol'L"1. The complexes of CCTS (Ohga, Kurauchi & Yanase, 1987), CCTS-2 and silver ion against three bacteria were studied. The bacteriostasis zone diameters of the complex of CCTS-2 and Ag+ (CCTS-2—Ag+) containing 0.00355 mmol Ag+ against Staph. Aureus, E.coli and Pseudomonas aeruginona are 11, 10 and 7.5 millimeter accordingly while those of the complex of CCTS and Ag+ (CCTS— Ag+) at the same condition are 11, 10 and 6.0 millimeter accordingly. This research will be useful for designing crosslinked-chitosan-based adsorption for preconcentration of Ag+ for medical bacteriostasis.(3) A new adsorbent for bilirubin, chitosan immobilized with j5-cyclodextrins (CTC), has been prepared by the reaction of chitosan and allyl-substituted j8-cyclodextrins. Its structure has been confirmed by infrared spectra analysis and X-ray diffraction analysis. The experimental results showed this adsorbent for bilirubin has a higher capacity 6.33 mg'g"1 than CTS at initial concentration 14.5 mg* L1 at 20 °C. It was mainly derived from the torus of j?-cyclodextrins on CTC and hydrogen bond between CTC and bilirubin. The adsorption for BR of CTC was accorded with Freundlich isothermal equation. This new adsorbent might be applied as biomedical adsorbents in the removal of bilirubin in medical administration.(4)We first prepared the intermediate hydroxylpropyl chloride of chitosan(CSl). By the reaction of hydroxylpropyl chloride of chitosan and /?-cyclodextrins, a novel chitosan grafted withj#-cyclodextrins (CC) has been gained. Their structures were characterized by IR and X-ray diffraction, which were in accordance with the designed ones. The apparent grafted amount of j#-cyclodextrins was 25.48 //mol^g"1 by UV-9100 ultraviolet-visible spectrophotometer. The influences of initial concentration, adsorption time, pH, and ion strength on adsorption capacity for salicyclic acid were studied. This kind of modified resin has a higher adsorption capacity for salicyclic acid than chitosan itself (CTS). The maximium adsorption forsalicyclic acid on CC was 55.2% while on CTS was 49.1%. The chitosan grafted with jtf-cyclodextrins (CC) needed about 180 minute to get adsorption equilibrium.(5)The novel chitosan microspheres grafted with jS-cyclodextrins (CMGC) were prepared by means of the reaction of chitosan microspheres which were prepared successfully by phase-inversion method, and mono-(6-p-tosyl)- jS-cyclodextrins ()8-CD-OTs-6) gained by the reaction of /Moluenesulfonyl chloride (TsCl) and j3-cyclodextrin (ji-CD). Their structures were proved by Fourier transform infrared spectral analysis (FT-IR), X-ray powder diffraction analysis, and 13Carbon Nuclear Magnetic Resonnance (13C NMR); the configuration of CMGC was characterized by scanning electron micrograph (SEM) and transmittance electron micrograph (TEM). The inclusion complex of CMGC with iodine was prepared and its inclusion ability was studied. The experimental results showed that some iodine was included with CMGC and formed a stable inclusion. The stable complex of CMGC and iodine (CMGC-I) shows good antibacterial effect.(6)The new diethylene triamine derivative of chitosan was synthesized by the reaction of diethylene triamine and chitosan activated with epoxy. The product contained amino functional groups, secondary amine and polar hydroxyl groups in its skeleton. Its structure was proved by elemental analysis, infraed spectra analysis, and X-ray diffraction analysis. It was in accordance with expected one. The static adsorption properties for Pd2+> Ag\ Ni2\ Cu2\ Co2+andCd2+ were studied. The experimental results demonstrated the new diethylene triamine derivative of chitosan has higher adsorption capacity for metal ions. The adsorption capacities for Ag+ and Pd2+ were 1.29 and 1.15 mmol'g \ respectively. In the coexistence of Cu2+and Ni2+, it had a high adsorption selectivity for Ag+ ion. The selectivity coefficients were K Ag+/CB2+ =11.73 for CTSN and KAg+/c?2+=3.2 for CCTS. The adsorption capacity for Ag+ was greatly influenced by pH and ion strength.The main innovative points are as follows:(l)The crosslinked chitosan with 4' -formal benzo-15-crown-5 loaded withpalldium chloride was first applied in asymmetric hydrogenation. The new catalyst has been found to selectively catalyze the hydrogenation of a -phenylethanone intothe chiral alcohol;a -phenyl ethanol under the mild condition. XPS analysis has been used to characterize the mechanism of 4'-formal benzo-15-crown-5 loaded with palldium chloride and the influences on catalytic hydrogenation were discussed.(2)New di-secondary amine type crown ethers crosslinked chitosan adsorbed silver ion was first used in antibacteria. The antibaterial activity of it was studied;which provided new idea for magnifing the antibacterial activity and application ofchitosan.(3)Considering good inclusive behavour of jS-cyclodextrins and biocompatibility of chitosan;new routes and application about the reaction of /?-cyclodextrins and chitosan are as follows:?The novel chitosan microspheres grafted with jS-cyclodextrins adsorbediodine to obtain the adsorbent which was applied in antibacterial tests. It had thesame antibacterial activity as pure iodion.However;it was more stable than pureiodine.?By means of the new way of the reaction of chitosan and allyl-substitutedj3-cyclodextrins;biocompatible chitosan immobilized with ft — cyclodextrinswas obtained. In the scope of low concentration;its adsorption on bilirubin wasstudied.(3)By the new reaction of hydroxylpropyl chloride of chitosan and fi-cyclodextrins;a novel chitosan grafted with P -cyclodextrins has been gained.It was first applied in the adsorption of salicyclic acid and the influences onadsorbing salicyclic acid were also studied.(4)The new derivative method for chitosan was searched to prepare new diethylene triamine derivative of chitosan. The adsorption on heavy metal ions was discussed.