• Title/Summary/Keyword: carboxylic acid

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Addition Polymerization of 5-Norbornene-2-carboxylic Acid Esters Using Palladium Catalyst System: Synthesis of Monomers, Effect of Their Stereochemistry on Polymerization Behavior (Palladium 촉매를 이용한 5-Norbornene-2-carboxylic Acid Esters의 부가 중합: 단량체의 합성, 단량체의 Stereochemistry(Endo-, Exo-이성질체)가 고분자의 중합 거동에 미치는 영향)

  • Chung, Hae-Kang;Shim, Hyoug-Sub;Jeon, Seung-Ho;Kim, Ji-Heung;Nam, Sung Woo;Jeon, Boong Soo;Kim, Young Jun
    • Polymer(Korea)
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    • v.39 no.3
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    • pp.487-492
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    • 2015
  • The effects of chemical structure of alkyl groups of norbornene carboxylic alkyl esters(methyl, octyl, 4-chlorobenzyl) and endo/exo ratios of norbornene monomers on activity of palladium catalyst and polymerization behavior were investigated. Norbornene ester monomers were synthesized from the reaction of 5-norborene-2-carboxylic acid and various alcohols. Polymerization catalyst, di-${\mu}$-chloro-bis(-methoxybicyclo[2,2,1]-hept-2-ene)palladium(II) (DCBMP), was synthesized according to the literature procedure and silver hexafluoroantimonate ($AgSbF_6$) was used as a conjugate anion source. Gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) were the principal techniques for polymer characterization and $^1H$ NMR spectroscopy was used for chemical structures determination of monomers and polymers. For all of the norbonene alkyl esters GPC data showed that when the amounts of endo isomers exceeded those of exo isomers decreased molecular weight polymers were obtained probably due to the decreased catalyst activity. Polymerizations were conducted by varying the monomer/catalyst mole ratios (100:1, 200:1, 300:1). When 300:1 monomer/catalyst ratio was employed it was possible to synthesize high molecular weight ($M_n=27500g/mol$), film forming polymer from exo-norbornene carboxylic acid octyl ester.

Cyclocondensation of 2-Substituted-4-hydroxy-2H-1, 2-benzothiazine-3-carboxylic acid 1, 1-dioxides with Dicyclohexylcarbodiimide (2-치환 4-Hydroxy-2H-1, 2-benzothiazine-3-carboxylic acid 1, 1-dioxidies와 Dicyclohexylcarbodiimide의 축합환화 반응)

  • 서정진;홍유화
    • YAKHAK HOEJI
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    • v.31 no.1
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    • pp.40-41
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    • 1987
  • 4-Hydroxy-2H-1, 2-benzothiazine-3-carboxylic acid 1a was reacted with 2 equivalents of dicyclohexylcarbodiimide (DCC) to give 2-cyclohexyl-3-cyclohexylimino-4,5-dihydro-1H-imidazo [1,5-b][1,2] benzothiazine-10, 10a-dyhydro-1,10-dione 5,5-dioxide 2a and dicyclohexylurea (DCU). On the other hand 2-substituted-4-hydroxy-2H-1, 2-benzothiazine-3-carboxylic acid 1,1-dioxide 1b or c was reacted with DCC to give 2-cyclohexylimino-3-cyclohexyl-5-alkyl-4-oxo-2,5H-1,3-oxazino [5,6-c]-1,2-benzothiazine 6,6-dioxide 2b or c and DCU.

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Synthesis of 6- Hydroxy-7 -methoxychroman-2-carboxylic Acid Dialkylaminoalkylamides (6-하이드록시-7-메톡시크로만-2-카복실산 디알킬아미노알킬아마이드 합성)

  • Kwak, Jae-Hwan;Lee, Keum-Ho;Jung, Jae-Kyeong;Cho, Jung-Sook;Lee, Hee-Soon
    • YAKHAK HOEJI
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    • v.50 no.5
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    • pp.322-325
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    • 2006
  • In the course of developing novel antioxidants, we synthesized four of 6-hydroxy-7-methoxy-4-oxochroman-2carboxylic acid dialkylamides (3a-d) $(13{\sim}18%)$ and four of 6-hydroxy-7-methoxychroman-2-carboxylic acid dialkylamides (4a-d) $(52{\sim}89%)$, incorporating the basic amine functionality. None of these compounds exhibited significant antioxidant activity possibly due to the hydrophilic character of the basic amine side chains.

Phenazine 1-carboxylic acid resistance in phenazine 1-carboxylic acid producing Bacillus sp. B-6

  • Kim, Kyoung-Ja
    • BMB Reports
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    • v.33 no.4
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    • pp.332-336
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    • 2000
  • Phenazine 1-carboxylic acid (PCA) is an antifungal antibiotic isolated from a culture filtrate of Bacillus sp. B-6 producing an acyl CoA synthetase inhibitor. This antibiotic is reported as an inhibitor of an acyl CoA synthetase from Pseudomonas sp.. Bacillus sp. B-6 was resistant to PCA up to 350 ${\mu}g/ml$. We investigated the mechanism of the resistance of Bacillus sp. B-6 to PCA. The rate of growth in a medium containing up to 100 ${\mu}g/ml$ was as rapid as the PCA-free medium. At a PCA concentration of 300 ${\mu}g/ml$, the growth rate was more than half that of the control. In this work, we purified acyl CoA synthetase from Bacillus sp. B-6 and found that this acyl CoA synthetase was much less sensitive to PCA than the acyl CoA synthetase from other source. These findings suggested that the insensitivity of Bacillus sp. B-6 acyl CoA synthetase plays an important role in the PCA resistance of this bacterium.

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Sensitive and Mild Fluorogenic Reagents for Biogenic Carboxylic Acids in HPLC

  • Ushijima, Tamano;Saito, Mikihiko;Sasamoto, Kazumi;Ohkura, Yosuke;Ueno, Keiyu
    • Analytical Science and Technology
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    • v.8 no.4
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    • pp.545-551
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    • 1995
  • Five acid hydrazides as precolumn fluorescence derivatization reagents for carboxylic acids in HPLC, which have the benzofuran or benzothiazole moiety conjugated to a furan, thiophene or oxazoline ring, were synthesized and examined in view of reactivity, separability and sensitivity. Of these hydrazides, 2-(5-hydrazinocarbonyl-2-oxazolyl)-5,6-dimethoxybenzothiazole (BTOH) was most favorable. The detection limit of lauric acid as a model acid was 0.1 pmol per $10-{\mu}l$ injection volume at S/N=3, which was roughly equal to that of an analogous compound, 2-(5-hydrazinocarbonyl-2-furyl)-5,6-dimethoxybenzothiazole. The reagent allowed rapid assays of carboxylic acids ($C_{12:0}-C_{20:4}$) within 20 min with satisfactory scparability. The method was applied to the determination of fatty acids in human sera from healthy volunteers as well as from patients with diabetes or thyroid dysfunction.

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Mechanisms of Carboxylic Acid Attraction in Drosophila melanogaster

  • Shrestha, Bhanu;Lee, Youngseok
    • Molecules and Cells
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    • v.44 no.12
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    • pp.900-910
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    • 2021
  • Sour is one of the fundamental taste modalities that enable taste perception in animals. Chemoreceptors embedded in taste organs are pivotal to discriminate between different chemicals to ensure survival. Animals generally prefer slightly acidic food and avoid highly acidic alternatives. We recently proposed that all acids are aversive at high concentrations, a response that is mediated by low pH as well as specific anions in Drosophila melanogaster. Particularly, some carboxylic acids such as glycolic acid, citric acid, and lactic acid are highly attractive to Drosophila compared with acetic acid. The present study determined that attractive carboxylic acids were mediated by broadly expressed Ir25a and Ir76b, as demonstrated by a candidate mutant library screen. The mutant deficits were completely recovered via wild-type cDNA expression in sweet-sensing gustatory receptor neurons. Furthermore, sweet gustatory receptors such as Gr5a, Gr61a, and Gr64a-f modulate attractive responses. These genetic defects were confirmed using binary food choice assays as well as electrophysiology in the labellum. Taken together, our findings demonstrate that at least two different kinds of receptors are required to discriminate attractive carboxylic acids from other acids.

Electrochemical Oxidation of Glucose at Nanoporous Gold Surfaces Prepared by Anodization in Carboxylic Acid Solutions (카복실산 용액에서 양극산화에 의해 형성된 나노다공성 금 표면상의 전기화학적 글루코오스 산화)

  • Roh, Seongjin;Jeong, Hwakyeung;Lee, Geumseop;Kim, Minju;Kim, Jongwon
    • Journal of the Korean Electrochemical Society
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    • v.16 no.2
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    • pp.74-80
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    • 2013
  • We investigate the formation of nanoporous gold (NPG) surfaces by anodization in three carboxylic acid (formic acid, acetic acid, and propionic acid) solutions and the electrochemical oxidation of glucose at NPG surfaces. Among three carboxylic acids, formic acid provided the most efficient conditions for NPG formation towards glucose oxidation. The optimized conditions during anodization in formic acid for glucose oxidation were 5.0 V of applied potential and 4 hour of reaction time. Electrocatalytic activities for glucose oxidation at NPG surfaces prepared by anodization in carboxylic acids were examined under the absence and presence of chloride ions, which were compared to those observed at NPG prepared in oxalic acid solutions. The application NPG prepared by optimized anodization conditions in formic acid to the amperometric detection of glucose was demonstrated.