Biomedical subjects

JS Huang

Publications and source records attributed to JS Huang.

At least 19 recordsLinked to original sources

PubMed2000

Amidation of unfunctionalized hydrocarbons catalyzed by ruthenium cyclic amine or bipyridine complexes

Selective amidation of simple hydrocarbons with pre-isolated and in-situ formed iminoiodanes catalyzed by ruthenium complexes [Ru(III)(Me(3)tacn)(CF(3)CO(2))(3).H(2)O] (2b, Me(3)tacn = N,N', N"-trimethyl-1,4,7-triazacyclononane) and cis-[Ru(II)(6, 6'-Cl(2)bpy)(2)Cl(2)] (3, 6,6'-Cl(2)bpy = 6,6'-dichloro-2, 2'-bipyridine) was investigated. With PhI=NTs as nitrogen source, both catalysts efficiently promote the amidation of adamantane, cyclohexene, ethylbenzene, cumene, indan, tetralin, and diphenylmethane to afford N-substituted sulfonamides in 80-93% yields with high selectivity. Competitive amidations of para-substituted ethylbenzenes and kinetic isotope effect for the amidation of cyclohexene/cyclohexene-d(10) suggest that the amidation processes probably proceed via the hydrogen abstraction by a reactive Ru=NTs species to form a carboradical intermediate. The amidation with PhI(OAc)(2)/TsNH(2) gave results comparable to those obtained with PhI=NTs. Extension of the "PhI(OAc)(2)/TsNH(2) + catalyst 2b or 3" protocol to MeSO(2)NH(2) and PhCONH(2) with ethylbenzene as substrate produced the corresponding N-substituted amides in up to 89% yield.

Journal Article↗

PubMed2000

Bis axial ligation of simple imine and methyleneamido groups by ruthenium porphyrins

Bis(N-ethylideneethanamine)ruthenium(ii) porphyrins, [Ru11(Por)(N(Et)=CHMe)2] (Por=TTP, 4-Cl-TPP), were prepared by the reaction of dioxoruthenium(VI) porphyrins with triethylamine in approximately 85% yields. The reaction between dioxoruthenium(VI) porphyrins and benzophenone imine afforded bis(diphenylmethyleneamido)ruthenium(IV) porphyrins, [Ru(IV)(Por)(N=CPh2)2] (Por=TTP, 3,4,5-MeO-TPP), in approximately 65% yields. These new classes of metalloporphyrins were characterized by 1H NMR, UV/Vis, and IR spectroscopy as well as by mass spectrometry and elemental analysis. The X-ray crystallographic structures of [Ru(II)(TTP)(N(Et)=CHMe)2] and [Ru(IV)(3,4,5-MeO-TPP)(N=CPh2)2] revealed an axial Ru-N bond length of 2.115(6) A for the imine complex and 1.896(8) A for the methyleneamido complex. Each of the N=CPh2 axial groups in [Ru(IV)(3,4,5-MeO-TPP)(N=CPh2)2] adopts a linear coordination mode with a corresponding Ru-N-C angle of 175.9(9)degrees. Spectral and structural studies revealed essentially single bonding character for the bis(imine) complexes but a multiple bonding character for the bis(methyleneamido) complexes with respect to their axial Ru-N bonds.

Journal Article↗

PubMed1998

Kinetics of denitritification and denitratification in anoxic filters

Denitritification and denitratification in anoxic filters were performed to generate experimental data. Also, a kinetic model of denitratification that accounts for intrinsic biokinetics and hydrodynamic behavior of the biofilter is proposed. In denitritification, the simulated results are in good agreement with the experimental data; and a higher nitrite influent concentration gives a higher nitrite reduction efficiency if the denitrifying loading is kept the same. In denitratification, the intermediate nitrite tends to accumulate, and a higher denitrifying loading results in a higher nitrite effluent concentration. By inserting biological and physical parameter values into the kinetic model, the variations in distributed fractions of nitrate-reductase (f) and nitrite-reductase (1-f) with different denitrifying loadings can be estimated by fitting in experimental data. The estimated f increased with an increase in denitrifying loading, implying that a higher denitrifying loading results in a higher nitrite effluent concentration. From parametric sensitivity analyses, the parameter f is more sensitive than other biological and physical parameters. Accordingly, the proposed kinetic model of denitratification can be used to predict the treatment performance of anoxic filters appropriately. Copyright 1998 John Wiley & Sons, Inc.

Journal Article↗

PubMed1996