• Journal of the Korean Ceramic Society
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• v.24 no.6
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• pp.561-571
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• 1987

In case of glass ceramics and powder preparation from the metalakoxide solutions, metalakoxide solutions with a various species of alkoxy groups have unique characteristics. Therefore, in this study, the mixing ability of homogeneous sol, gel morphology and physical properties of gels were investigated by the changes in terms of the different four alkoxy groups, CH3-, C2H5-, i-C3H7-n-C4H9-, along with the catalyst for the purpose of the observation about the homogenous transition range from sol to gel. As a result, when the fixed condition was mol ratio of H2O/Si(OR)4=2.0 and variables were batch composition and addition amount of catalyst, the characteristics of Tetra-normal-Butoxysilane and Tetra-iso-propoxysilane systems had very narrow sol-gel conversion region than Tetramethoxysilane and Tetraethoxysilane system. And silicon-alkoxide, systems having narrow sol-gel conversion region were enlarged by addition of catalyst. In viewpoint of the weight loss of gel produced by hydrolysis of silicon alkoxide systems with different four alkoxy groups, the amounts of weight loss of gel containing large molecular alkoxy groups were much more than those of small molecular alkoxy group.

• Journal of the Korean Society of Industry Convergence
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• v.12 no.3
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• pp.143-147
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• 2009

The enantioselective reduction of representative prochiral alkyl-aryl ketones with a new chiral alkoxy-amine-aluminum derivatives from aluminum hydride and ${\alpha},{\alpha}$-diphenyl-${\beta}$-amino alcohols, such as (S)-(-)-2-amino-3-methyl-1,1-diphenylbutan-1-ol(AMDPB) and (S)-(-)-2-(diphenylhydroxy-methyl)pyrrolidine(DPHMP), in THF at $0^{\circ}C$ was studied. In the reduction of alkoxy-amine-aluminum derivatives, acetophenone, propiophenone, isopropiophenone, and butyrophenone are reduced to corresponding aromatic secoundary alcohols with 34~60 % enantiomeric excess of (S)-isomers. For such ketones, the optical induction was enhanced by increasing a size of alkyl groups.

• YAKHAK HOEJI
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• v.46 no.3
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• pp.155-160
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• 2002

Through a modification of allicin structure a disagreeable odor and chemical instability of allicin can be improved. 3-Alkoxy-6-allylthiopyridazine derivatives exhibit a superior effect for prevention and treatment of hepatic diseases induced by carbon tetrachloride and aflatoxin B1 and for prevention of human tissues from radiation. These compounds inhibit also efficiently SK-Hep-1 cell proliferation through induction of apoptosis. So another 4,5-mono- or di-substituted 3-alkyloxy-6-allylthiopyridazine derivatives were synthesized on purpose to find out SAR of allylthiopyridazine in hepatoprotective and hepatotherapeutic acitivitis and to develop more effective drug candidate.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2471-2476
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• 2007

A series of titanium complexes containing terdentate β-ketoiminate ligands were found to be efficient for the ring-opening polymerization of ε-caprolactone (ε-CL), producing poly(ε-caprolactone) (PCL) with bimodal distribution. Steric factors imposed by methyl substituents on the back bone of the alkoxy group affected significantly the polymerization rate and physical properties of the resulting PCL. Intra- and intermolecular transesterifications rather than disproportional rearrangements were responsible for the bimodal behavior and for the change in the molecular weight (Mw). Dilution with toluene reduced yield, and lowered polydispersity (PDI) and Mw of PCL, while the catalytic activities of the dimeric complex, [Ti(Oi-Pr)2(N-alkoxy-β- ketoiminate)]2 and Ti(Oi-Pr)4 were not sensitive to the added solvent. The dimeric complex showed living character, while other catalysts suffered from chain termination reactions.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.172.2-173
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• 2003

3-Alkoxy-6-allylthiopyridazine derivatives showed the strongest protective effect against oxidative stress and their anticancer effect determined on the growth of SK-Hep-l hepatocellular carcinomar cells. The allythio group as a pharmacologically active group was introduced into pyridazine nucleus and a substituent such as halogen or alkoxy was also introduced into paraposition of allylthio group. Five kinds of 3-alkoxy-6-allylthiopyridazine derivatives were synthesized and their chemoprotective activities examined in rats exposed to aflatoxin $B_1$-toxicant. (omitted)

• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.1067-1070
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• 2012

• Bulletin of the Korean Chemical Society
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• v.27 no.10
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• pp.1671-1673
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• 2006

• Journal of the Korean Chemical Society
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• v.48 no.3
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• pp.331-334
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• 2004

• Bulletin of the Korean Chemical Society
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• v.20 no.1
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• pp.42-48
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• 1999

We have performed a quantum-chemical investigation on the conformations and electronic properties of a variety of methoxy-substituted poly(p-phenylenevinylenes) (PPVs) to elucidate the effects of alkoxy substitution. Geometrical parameters for the polymers were fully optimized through Austin Model I (AM I) semi-empirical Hartree-Fock (HF) band calculations. Electronic properties of the polymers were obtained by applying the AM I optimized structures to the modified extended Huckel method. To confirm validity of the AM I conformational results, we also carried out ab initio HF calculations with the 6-31G (d) basis set for a variety of methoxy-substituted divinylbenzenes. It is found that the potential energy surfaces of alkoxy-substituted PPVs are quite shallow around the planar conformations, suggesting that the prepared films possess a variety of conformations with different torsion angle in the solid state, depending on the synthetic conditions. When two alkoxy groups are concurrently substituted at the adjacent sites in the phenylene ring, these groups are subject to rotating around the C(sp2)-O bonds by 70-80° to avoid the strong steric repulsion between them. Consequently, the overlap between the π-type p orbital of oxygen and the π molecular orbitals of the polymer decreases. This leads to a wide gap and a high oxidation potential for tetramethoxy-substituted PPV, compared to those of dialkoxy-substituted PPV.

• Journal of Microbiology and Biotechnology
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• v.13 no.4
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• pp.632-635
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• 2003

Novel poly(3-hydroxyalkanoates), PHAs, having either methoxy or ethoxy groups as the terminal hydrophilic moieties, were biosynthesized by Pseudolnons oleovorans. grown either solely with 11-alkoxyundecanoic acid or 8-alkoxyoctanoic acid, or grown with a mixture of 6-alkoxyhexanoic acid and nonanoic acid. The PHA synthesized from 11-methoxyundecanoic acid consisted of 88 mol% 3-hydroxy-7-methoxyheptanoate and 12 mol% 3-hydroxy-9-methoxynonanoate. However, the PHA produced from 11-ethoxyundecanoic acid consisted of 56 mol% 3-hydroxy-5-ethoxypentanoate and 44 mol% 3-hydroxy-7-ethoxyheptanoate. The high solubility of the PHAs in methanol and ethanol indicated that the alkoxy groups in the side chains resulted in the formation of PHAs with an enhanced hydrophilicity.