• Applied Chemistry for Engineering
• /
• v.9 no.5
• /
• pp.719-725
• /
• 1998

Tridentate Schiff base ligands were prepared by the reactions of salicylaldehyde and 2-hydroxy-1-naphthaldehyde with 2-aminophenol and 2-amino-p-cresol. And then Cu(II) complexes of those ligands were synthesized. The structures and properties of ligands and their complexes were studied by elemental analysis, $^1H$-NMR, IR, UV-visible spectra, and thermogravimetric analysis. The mole ratio of Schiff base to the metal of complexes was found to be 1:1. Cu(II) complexes were contemplated to be four-coordinated square planar configuration containing one water molecule. The redox process of ligands and complexes in DMSO solution containing 0.1 M TBAP as a supporting electrolyte was investigated by cyclic voltammetry and differential pulse voltammetry with glassy carbon electrode. The redox process of the tridentate Schiff base ligands was totally irreversible. The redox process of Cu(II) complexes was quasi-reversible and diffusion-controlled as one electron by one step process Cu(II)/Cu(I). The reduction potentials of the Cu(II) complexes shifted in the positive direction in the order of [Cu(II)(HNIPC)($H_2O$)]>[Cu(II)(HNIP)($H_2O$)]>[Cu(II)(SIP)($H_2O$)]>[Cu(II)(SIPC)($H_2O$)].

• Proceedings of the Korea Concrete Institute Conference
• /
• 1995.04a
• /
• pp.142-147
• /
• 1995

In this study, styrene-maleic anhydride copolymer (SMA) was synthesized from styrene and maleic anhydride and further reacted with sulfuric acid to obtain water-soluble SMA and the flow and strength tests of cement mortar mixed with copolymers were carried out to evaluate the capability of copolymers as high range water reducer for the concrete. It was found from flow experiment that the fluidity of cement mortar mixed with sulfonated SMA (SSMA) was larger than that miced with aminophenol-substituted SSMA (SmSMA). The decreasing rate of the flow of cement mortar mixed with SSMA and SmSMA was decreasing rate of the flow of cement mortar mixed with SSMA and SmSMA was significantly lower than that mixed with naphthalene condensate (NSC). The compressive strength of the hardened cement mortars containing 0.5% copolymers after 28 days curing was examined. The compressive strength of hardened cement mortar containing SSMA and SmSMA was increased up to 32% and 13%, respectively, when compared to the plain. As the results, the copolymers (SSMA and SmSMA) used in this study are greatly expected as a good high range water reducers for the concrete.

• The Korean Journal of Pesticide Science
• /
• v.10 no.1
• /
• pp.66-68
• /
• 2006

New synthetic method of 2-mercaptobenzoxazoles and 2-mercaptobenzimidazoles was established using elemental sulfur, dichloromethane, inorganic base and catalysts in alcohol solvents. This reaction condition gave products in high yields.

• YAKHAK HOEJI
• /
• v.43 no.1
• /
• pp.68-76
• /
• 1999

Phenoxazinone synthase catalyzes the oxidative condensation of two molecules of substituted o-aminophenol to the phenoxazinone chromophore of actinomycin. Mutant strain, Streptomyces sp. V-8-M-1 producing higher phenoxazinone synthase, was obtained from Streptomyces sp. V-8 by treatment of N-methyl-N'-nitro-N-nitrosoguanidine. The phenoxazinone synthase was purified from extract of mutant strain of Streptomyces sp. V-8-M-l by successive steps of streptomycin sulfate, ammonium sulfate precipitation. DEAE-cellulose and Sephadex G-200 column chromatography. Molecular weight of the enzyme was 360,000 daltons. The enzyme was composed of octamer of a single subunit of 45,000 daltons. The Km value and Vmax value for 3-HAA were $14.9{\;}{\mu}M$ and 9.5 mg/U, respectively. The optimal pH and temperature for the enzyme activity were 9.0 and $25~30^{\circ}C$, respectively. Treatment of the enzyme with group specific reagents, phenylglyoxal, p-hydroxymercury-benzoate, Nbromosuccinimide, 5.5'-dithiobis-nitrobenzoic acid and ethylmaleimide resulted in loss of enzyme activity, which shows arginine and cysteine residues are at or near the active site.

• Journal of the Korean Chemical Society
• /
• v.53 no.6
• /
• pp.671-676
• /
• 2009

Described here for the first time is an investigation on geometrical and electronic molecular structure of metol (N-methyl-p-aminophenol sulphate) as corrosion inhibitor of steel using density functional theory (DFT) calculations. Quantum chemical parameters such as highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELUMO), energy gap ((${\Delta}E$), Mulliken charges (($q_M$) and natural atomic (($q_n$) charge have been calculated both for gas and aqueous phases by using B3LYP/6-31G+(d,p) basis set. The relation between the inhibition efficiency and quantum chemical parameters have been discussed in order to elucidate the inhibition mechanism of the title compound.

• Elastomers and Composites
• /
• v.53 no.3
• /
• pp.141-149
• /
• 2018

A series of aromatic poly(o-hydroxyamide)s (PHAs) were synthesized by the direct polycondensation reaction of 4,4′-(2,3-quinoxalinedioxy) dibenzoic acid and/or 4,4′-(2,3-pyridinedioxy) dibenzoic acid with bis(o-aminophenol) including 2,2-bis-(amino-4-hydroxyphenyl)hexafluoropropane. The PHAs exhibited inherent viscosities in the range of 0.17-0.35 dL/g at $35^{\circ}C$ in a DMAc solution. These polymers showed low inherent viscosities and yielded brittle films. All the PHAs showed excellent solubility in aprotic solvents such as DMAc, DMSO, NMP, and DMF at room temperature and in less polar solvents such as pyridine and THF. However, all the PBOs were only partially soluble in $H_2SO_4$. The PBOs exhibited 10% weight loss at temperatures in the range of $537-551^{\circ}C$. The maximum weight loss temperature increased with an increase in the content of the quinoxaline-containing monomer. The residue of the PBOs showed a weight loss of 45.8-56.7% at $900^{\circ}C$ in a nitrogen atmosphere.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.12
• /
• pp.4109-4116
• /
• 2012

An efficient solid-phase methodology has been developed for the synthesis of 2-amino and 2-amidobenzo[d]-oxazole derivatives. The key step in this procedure involves the preparation of polymer-bound 2-aminobenzo-[d]oxazole resins 4 by cyclization reaction of 2-hydroxy-phenylthiourea resin 3. The resin-bound 2-hydroxyphenylthiourea 3 is produced by the addition of 2-aminophenol to the isothiocyanate-terminated resin 2 and serve as a key intermediate for the linker resin. This core skeleton 2-aminobenzo[d]oxazole resin 4 undergoes functionalization reaction with various electrophiles, such as alkylhalides and acid chlorides to generate 2-amino and 2-amidobenzo[d]oxazole resins 5 and 6 respectively. Finally, 2-amino and 2-amidobenzo[d]oxazole derivatives 7 and 8 are then generated in good yields and purities by cleavage of the respective resins 5 and 6 under trifluoroacetic acid (TFA) in dichloromethane ($CH_2Cl_2$).

• Bulletin of the Korean Chemical Society
• /
• v.31 no.12
• /
• pp.3663-3667
• /
• 2010

Acetaminophen (N-acetyl-p-aminophenol) is one of the most popular analgesic and antipyretic drugs. An isotope dilution mass spectrometric method based on LC/MS was developed as a candidate reference method for the accurate determination of acetaminophen in pharmaceutical product. After spiking an isotope labeled acetaminophen (acetyl-$^{13}C_2$, $^{15}N$-acetaminophen) as an internal standard, tablet extracts were analyzed by LC/MS in a selected reaction monitoring (SRM) mode to detect ions at m/z $152{\rightarrow}110$ and m/z $155{\rightarrow}111$ for acetaminophen and acetyl-$^{13}C_2$, $^{15}N$-acetaminophen, respectively. The repeatability and reproducibility of the developed ID/LC-MS method were tested for the validation and assessment of metrological quality of the method.

• Magazine of the Korea Concrete Institute
• /
• v.7 no.3
• /
• pp.156-163
• /
• 1995

In the previous study, styrene mdleic dnhydride copolymer(SMA) as synthesized flom styrene and rnale~c dnhydr~de and further redcted with sulfuric acid to obtam water soluble SMA. In thls study, the flow dnd strcngth tests of cement mortar rmxed wth copolymers wele carried out to evaluate the capability of copolymers as high range water reducer for the con crete. It was found from flow exper~ment that the fluidity of cenient mortar rmxed wth sulfonated SMA(SSMAj was larger thdn that mxed ulth amnophenol substituted SSMA (SmSMAj. The decreasing rate of the flow of cement mortar rmxed ulth SSMA and SmSMA was significantly lower than that mixed ulth naphthalene condensate(NSC) The compressslve strength of the hardened cement mortars containing 0.5% copolymers after 28 dys curing was exarmned. 'The compressive strength of hdrdened cement mortar containing SSMA and SmSMA was mcreased up to 31% and 13%, respectively, when omp pared to the plain. As the results, the copolyniers(SSMA and SrnSMA) used in thls study are greatly expected as a good high range water reducers for the concrete.

• Journal of the Korean Chemical Society
• /
• v.34 no.2
• /
• pp.189-196
• /
• 1990

8-Acyl-2-hydroxyphenazine-5,10-dioxides and 8-acyl-2-aminophenazine-5,10-dioxides were synthesized by the reaction of hydroquinone and 4-aminophenol with 6-acylbenzofuroxans which had been obtained from acetanilide and n-acyl chlorides bearing butanoyl, hexanoyl and octanoyl groups. The antimicrobial activities of these phenazine dioxide derivatives were investigated in terms of minimum inhibitory concentration by the common twofold dilution technique. It was observed that the antimicrobial activity of the phenazine dioxide derivatives bearing octanoyl group was stronger than that of those bearing butanoyl and hexanoyl groups in gram positive microorgamisms, but it was observed that the antimicrobial activity and the number of the carbon atom of acyl groups did not have any relation in gram negative microorganisms. When the activity of xanthine oxidase which is the key enzyme in the generation of superoxide anion radical ($O_2^-$), was measured in the presence of phenazine dioxide derivatives, the inhibitory action of the enzyme activity of 8-acyl-2-hydroxyphenazine-5,10-dioxides was increased in accordance with the number of the carbon atom of acyl groups.