• Bulletin of the Korean Chemical Society
• /
• v.23 no.10
• /
• pp.1477-1480
• /
• 2002

• Proceedings of the Korean Fiber Society Conference
• /
• 1993.06a
• /
• pp.59-59
• /
• 1993

• Bulletin of the Korean Chemical Society
• /
• v.19 no.10
• /
• pp.1080-1083
• /
• 1998

An efficient method for construction of 2-arylfiirans has been developed by ceric(IV) ammonium nitratemediated oxidative cycloaddition of cyclic and acyclic 1,3-dicarbonyl compounds to several alkynes. Reactions of 1,3-cyclohexanedione, 1,3-cyclopentanedione, and 2,4-pentanedione with several alkynes furnish 2-arylfurans in 26-75% yields. Extension of this technology to more complex 4-hydroxy-2-quinolone and 3-hydroxy-lH-phenalen-l-one with phenylacetylene also affords furoquinolinone and ftirophenalenone derivative in moderate yields. Reaction of 4-hydroxycoumarins with phenylacetylene give linear and angular furocoumarin derivatives as a mixture of regioisomer in good yields. The mechanistic pathway for the formation of 2-arylfurans has been also described.

• Nuclear Engineering and Technology
• /
• v.48 no.3
• /
• pp.727-732
• /
• 2016

A simple and rapid spectrophotometric method has been developed to enable the determination of plutonium concentration in an irradiated fuel solution in the presence of all fission products. An excess of ceric ammonium nitrate solution was employed to oxidize all the valence states of plutonium to +6 oxidation state. Interference due to the presence of fission products such as ruthenium and zirconium, and corrosion products such as iron in the envisaged concentration range, as in the irradiated fuel solution, was studied in the determination of plutonium concentration by the direct spectrophotometric method. The stability of plutonium in +6 oxidation state was monitored under experimental conditions as a function of time. Results obtained are reproducible, and this method is applicable to radioactive samples resulting before the solvent extraction process during the reprocessing of fast reactor spent fuel. An analysis of the concentration of plutonium shows a relative standard deviation of <1.2% in standard as well as in simulated conditions. This reflects the fast reactor fuel composition with respect to uranium, plutonium, fission products such as ruthenium and zirconium, and corrosion products such as iron.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.7 no.2
• /
• pp.83-92
• /
• 1999

Chitosan was prepared from chitin which was abstracted from wasted crab shells. Then itaconic acid was graft-copolymerized onto chitosan using ceric ammonium nitrate as a reaction initiator. To investigate the optimal grafting conditions, the influences of several factors on the grafting were studied, i. e., the concentrations of CAN and itaconic acid, the reaction temperature and time. And to find out its flocculation ability. the flocculation test was carried out with a metal plating factory waste water. The state of graft-copolymer was identified through IR spectra analysis. The optimal grafting conditions and flocculation results were shown to be : concentration of ceric ammonium nitrate is $3.5{\times}10^3M$, reaction temperature is $40^{\circ}C$ and reaction time is 4hrs with 0.25M of the monomer(itaconic acid). Though flocculation tests using chitosan, grafted chitosan and cation, CODcr. metal ions removal rates were measured. The order of superiority is Itaconic acid grafted chitosan>Chitosan>Cationic polymer.

• Journal of the Korean Applied Science and Technology
• /
• v.25 no.4
• /
• pp.459-468
• /
• 2008

Methyl methacrylate(MMA) was grafted onto microcrystalline cellulose(MCC) with ceric ammonium nitrate(CAN) as a redox initiator at the various conditions. The cellulose triacetate(CTA) composite films added MCC and MMA-grafted MCC powders were prepared on a glass plate. The graft yield(GY) and graft efficiency(GE) of the grafted MCC were calculated with the simple equations by the weight balance method. The double bond of C=O on the grafted MCC surfaces was confirmed by the fourier transform infrared spectroscopy with attenuated total reflection(FT-IT ATR) spectrophotometer. After grafting, the degree of crystallinity of cellulose powders was decresed by judging from x-ray diffraction(XRD) data. Scanning electron microscope(SEM) photos showed the only solvent and CAN solution could change the roughness of MCC powders and the effect of powder dispersions in composite matrix. The tensile strength of MCC/CTA composite films was decreased with increase of MCC powder contents. When 5% grafted MCC was added, the tensile strength of grafted MCC/CTA composite films was increased from 82.3 MPa to 97.2 MPa. The thermal property of powders was also analyzed by the thermogravimetric analysis(TGA).

• Applied Chemistry for Engineering
• /
• v.3 no.2
• /
• pp.296-304
• /
• 1992

Porous polyurethane membrane was prepared by the phase inversion process with variable permeability in response to pH and solvent composition. Hydrophilic polymers were grafted on the surface of the symmetric porous membrane. Porous polyurethane membrane was obtained in DMSO/methanol. It was subsequently grafted with acrylamide on the surface with ceric ammonium nitrate(CAN) as a initiator, followed by the hydrolysis to obtain poly(acrylic acid-g-urethane) (PAA-g-PU) membrane. The change in permeability of vitamine $B_2$(riboflavin) was investigated through PAA-g-PU. For PAA-g-PU membrane, permeability increased with the decrease in pH, and with an increase in solvent content in sink solution.

• Microbiology and Biotechnology Letters
• /
• v.26 no.4
• /
• pp.338-344
• /
• 1998

New type of chitosan derivatives, chitosan-g-MAP, were synthesized by graft copolymerization of mono (2-methacryloyl oxyethyl) acid phosphate (MAP) into chitosan, in order to solubilize chitosan in water. Ceric ammonium nitrate was used as an initiator for graft copolymerization. The optimal conditions for graft copolymerization were determined on the basis of reaction temperature, time, and the concentration of initiator and monomer. The reaction conditions for the highest percentage of grafting were as follows: an initiator concentration, 3.5${\times}$10$\^$-3/ M; monomer concentration, 0.19 M; and reaction temperature, 40$^{\circ}C$ The reaction rate reached the maximum value after 4 hrs of reaction. Antifungal activity was tested against Candida albicans, Trichophyton rubrum and Trichophyton violaceum by using chitosan-g-MAP and two other chitosan samples which have degree of deacetylation of 70% (DA-7) and 90% (DA-90). Their antifungal activities were investigated in weak acidic range. Maximum antifungal activity of them was observed at pH 5.75. Chitosan-g-MAP inhibited thoroughly the growth of Candida albicans and Trichophyton violaceum. Howerver, DA-70 and DA-90 showed higher antifungal activities on Trichophyton rubrum than that of chitosan-g-MAP.

• Journal of the Korean Chemical Society
• /
• v.20 no.4
• /
• pp.309-315
• /
• 1976

An efficient separation method and the utilization of sericin are searched. Sericin was extracted with hot water from cocoons under atmospheric pressure. The separated sericin was gel-filtrated with Sephadex G-75 and G-150 at room temperature and at $70^{\circ}C$. The results indicated that sericin is consisted of only one fraction in elution diagram. In the graft copolymerization of acrylonitrile to sericin ceric ammonium nitrate was chosen as an initiatior. A maximum yield was obtained at certain concentration of the initiator confirming our previous experiments. Viscosity measurement of alkali-hydrolyzed graft copolymers indicated that the polyacrylonitrile graft had the molecular weight in the range of 7,000.

• Journal of the Korean Chemical Society
• /
• v.20 no.4
• /
• pp.299-308
• /
• 1976

Cerium (Ⅳ) ion-initiated graft copolymerizations of acrylamide and of acrylonitirile to silk fibroins were investigated. When acrylamide was used, the change in ceric ammonium nitrate concentration exhibited a maximum in degree of grafting at 0.01 M. Also observed was that the change in acetic acid content in reaction media gave a maximum in degree of grafting at 7% acetic acid in water. Degree of grafting was increased generally with increase in acrylamide concentration reaction time and reaction temperature. When acrylonitrile monomer was used for grafting,different results were obtained. Addition of nitric acid was more effective in enhancing the degree of grafting than the addition of acetic acid.Generally the grafting of acrylonitrile to silk fibroins was less efficient than the grafting of acrylamide. The portion of grafted silk fibroins insoluble in Lowe's reagent exhibited the IR absorption bands characteristics to both vinyl polymers and silk fibroins, indicating the grafting of vinyl monomers to silk fibroins. To examine the molecular weight of graft vinyl polymer, a sample of grafted silk was hydrolyzed by 10% sodium hydroxide. Viscosity measurements indicated that the molecular weight of the graft polymer was in the range of 105.