• Macromolecular Research
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• 제15권6호
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• pp.541-546
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• 2007

The combination of atom transfer radical polymerization (ATRP) and click chemistry was employed for the efficient preparation of well-defined block copolymers. Bromo terminated poly(methyl acrylate) (pMA-Br) was prepared by an ATRP initiator, ethyl-2-bromoisobutyrate (EBiB). Subsequently, the bromine chain end of pMA-Br was converted to an azide group by simple nucleophilic substitution reaction. ${\alpha}-Alkyn-{\omega}-bromo-functionalized$ polystyrene was also synthesized by ATRP using the alkyn-functionalized initiator, propargyl-2-bromoisobutyrate (PgBiB). In both cases, the conversion was limited to a low level to ensure a high degree of chain end functionality. Then the coupling reaction between the azide end group in $pMA-N_3$ and alkyn-functionalized PgBiB-pSt was performed by Cu(I)catalysis. This coupling reaction was monitored by gel permeation chromatography (GPC). The synthesized block copolymer was characterized by FT-IR, $^1H-NMR$ spectroscopy and $^1H-^1H$ COSY correlation spectroscopy.

• 한국결정학회지
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• 제15권1호
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• pp.5-8
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• 2004

Copper(I) bromide(CuBr) 와 pyrazine($C_4H_4N_2$, pyz)의 수열 반응으로 2차원 배위 고분자 [CuBr(pyz)] (1)이 얻어졌다. X-ray 구조 결정 결과, 고분자 1은 4.0${\times}$5.7 ${\AA}$ 크기를 갖는 직사각형 격자들을 토대로 한 2차원 그물 망 구조를 갖고 있었다. 고분자 1은 b-축 방향으로 통로(channel)를 갖고 있다.

• 대한화학회지
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• 제16권5호
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• pp.290-297
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• 1972

메탄올(95%) 용매내 $0{\sim}40^{\circ}C$에서 푸르푸랄, 5-메틸 및 5-브로모푸르푸랄의 알코올성 수산화칼륨에 의한 Cannizzaro 반응은 4차반응이며 푸르푸랄은 5-메틸푸르푸랄보다 3배, 5-브로모푸르푸랄은 푸르푸랄보다 10배 빠르게 진행된다. 그리고 이 반응에서 푸르푸랄, 5-메틸푸르푸랄, 5-브로모푸르푸랄의 활성화에너지는 각각 10.46 Kcal/mole, 16.27 Kcal/mole, 9.62 Kcal/mole이며 ${\Delta}H^{\neq}$ 와 ${\Delta}S^{\neq}$를 계산한 바 5-브로모푸르푸랄, 푸르푸랄, 5-메틸푸르푸랄의 순으로 증가 되었다.

• Biomolecules & Therapeutics
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• 제14권2호
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• pp.119-124
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• 2006

This study was performed to investigate the influence of the spinal adenosine $A_1$ receptors on the central regulation of blood pressure (BP) and heart rate (HR), and to define whether its mechanism is mediated by cyclic AMP (cAMP), cyclic GMP (cGMP) or potassium channel. Intrathecal (i.t.) administration of drugs at the thoracic level were performed in anesthetized, artificially ventilated male Sprague-Dawley rats. I.t. injection of adenosine $A_1$ receptor agonist, $N^6$-cyclohexyladenosine (CHA; 1, 5 and 10 nmol) produced dose dependent decrease of BP and HR and it was attenuated by pretreatment of 50 nmol of 8-cyclopentyl-1,3-dimethylxanthine, a specific adenosine $A_1$ receptor antagonist. Pretreatment with a cAMP analogue, 8-bromo-cAMP, also attenuated the depressor and bradycardiac effects of CHA (10 nmol), but not with cGMP analogue, 8-bromo-cGMP. Pretreatment with a ATP-sensitive potassium channel blocker, glipizide (20 nmol) also attenuated the depressor and bradycardiac effects of CHA (10 nmol). These results suggest that adenosine $A_1$ receptor in the spinal cord plays an inhibitory role in the central cardiovascular regulation and that this depressor and bradycardiac actions are mediated by cAMP and potassium channel.

• Natural Product Sciences
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• 제21권4호
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• pp.278-281
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• 2015

Chemical investigation on a colonial marine tunicate, Didemnum sp. led to the isolation of a series of indole alkaloids including a new (1) and two known metabolites (2-3). Based on the spectroscopic analysis including 1D and 2D NMR along with MS spectra, the structure of 1 (16-epi-18-acetyl herdmanine D) was elucidated as a new amino acid derivative. The absolute configuration of 1 was determined by comparison of specific rotation with the known compound. The structures of compounds 2 and 3 were also identified as bromoindole containing compounds N-(6-bromo-1H-indole-3-carbonyl)-L-arginine and (6-bromo-^1H-indol-3-yl) oxoacetamide, respectively, based on $^1H$ and $^{13}C$ NMR data, MS data and specific rotation value. Their pharmacological potentials as antibacterial agents and FXR antagonists were investigated, but no significant activity was found. However, the structural similarity of compound 1 to compound 4 suggested the anti-inflammatory potential of compound 1.

• 대한화학회지
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• 제25권6호
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• pp.390-393
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• 1981

${\beta}$-nitrostyrene 및 그 유도체에 Thioglycoic acid를 첨가시켜 다음과 같은 8가지 새로운 화합물을 합성하였다. s-[2-Nitro-1-phenylethyl]-thioglycolic acid; s-[2-nitro-1-(p-methyl)phenylethyl]-thioglycolic acid; s-[2-nitro-1-(p-methoxy)phenylethyl]-thioglycolic acid; s-[2-nitro-1-(p-chloro)phenylethyl]-thioglycolic acid; s-[2-nitro-1-(p-bromo)phenylethyl]-thioglycolic acid; s-[2-nitro-1-(p-nitro)phenylethyl]-thioglycolic acid; s-[2-nitro-1-(3-methoxy-4-ethoxy)phenylethyl]-thioglycolic acid; s-[2-nitro-1-(3,4,5-trimethoxy)phenylethyl]-thioglycolic acid. 이 물질들의 구조를 원소분석, UV, IR, NMR 스펙트럼등으로 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제25권8호
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• pp.1125-1129
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• 2004

This work assesses the potential of natural Analcime Zeolite as an adsorbent for preconcentration of lead (II) traces. Lead is quantitatively retained on 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol by column method with Analcime in the pH range of 5-6.5 and 2 mL $min^{?1}$ flow rate. Lead was removed from the column with 10.0 mL of 4 M hydrochloric acid and was determined by anodic stripping differential pulse voltammetry. 0.5ppb detection limit was obtained and linear dynamic range was 3 to $1.2{\times}10^5$ ppb in final solution with correlation coefficient of 0.999 and relative standard deviation of ${\pm}$ 1.2% (for eight replicate determination of 2.5 ${\mu}g\;mL^{?1}$ of lead). Various parameters such as the effect of pH, flow rate, instrumental conditions and interferences of some ions on the determination of lead have been studied in detail for optimization of conditions. The method was successfully applied for determination of lead in various samples.

• Bulletin of the Korean Chemical Society
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• 제26권1호
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• pp.51-56
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• 2005

A PVC membrane electrode for lead ion based on 1-phenyl-2-(2-quinolyl)-1,2-dioxo-2-(4-bromo) phenylhydrazone (PQDBP) as ionophore was demonstrated. The optimum composition of the membrane was 30 wt% poly(vinyl chloride), 60 wt% dibutyl phthalate as a plasticizer, 4 wt% ionophore and 6 wt% sodium tetraphenylborate as additive. The electrode exhibits a Nernstian response (28.7 mV decade$^{-1}$) for Pb$^{2+}$ over a wide concentration range (1.0 ${\times}$ 10$^{-1}$ to 1 ${\times}$ 10$^{-6}$ M) with a detection limit of 6.0 ${\times}$ 10$^{-7}$ M. This sensor has a short response time and can be used for at least 2 months without any divergence in potentials. The proposed electrode could be used in a pH range of 3.0-6.0 and revealed good selectivities for Pb$^{+2}$ over a wide variety of other metal ions. It was successfully applied as an indicator electrode for the potentiometric titration of lead ion with potassium chromate and for the direct determination of lead in mine.

• 대한화학회지
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• 제36권3호
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• pp.453-459
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• 1992

염화 삼메틸규소를 첨가하지 않고 에테르나 사염화탄소 중의 3-Aryl-3-bromopropanoyl chloride를 상온에서 2당량의 히드록실아민과 반응시켜 2,5-diarylisoxazolidin-3-ones 을 좋은 수율로 얻을 수 있었다. 그러나 $0^{\circ}C$에서 3-bromohydrocinnamoyl chloride 는 2당량의 벤질히드록실아민과 반응하여 N-benzyl-3-bromo-3-phenylpropanohydroxamic acid (72%) 와 N-benzyl-C-phenylnitrone (12%)을 생성하며 같은 조건하에서 3당량의 벤질히드록실아민을 사용하면 3-phenylisoxazolidin-5-one (41%) 과 2-benzyl-S-phenyl-isoxzolidin-3-one (38%)이 생성된다.

• Bulletin of the Korean Chemical Society
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• 제25권9호
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• pp.1346-1350
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• 2004

Pseudo-first order rate constants $(k_{obs})$ are reported for the following solvolyses in approximately isodielectric mixtures: 3- and 4-methoxybenzyl chloride, bromo- and chlorodiphenylmethane, and 4-chloro-, 4,4'-dichloro and 4-methyl-chlorodiphenylmethane in 0-80% v/v nitromethane-methanol mixtures; and bromo- and chlorodiphenylmethane and 4-methyl-chlorodiphenylmethane in various acetonitrile-methanol mixtures (in the range 0-50% v/v) at$25^{\circ}C.$ These data, and literature data for t-butyl halides (Cl, Br, and I), and for p-methoxybenzoyl chloride, show rate maxima in solvent compositions of ca. 30% aprotic cosolvent, explained by a stoichiometric solvent effect on electrophilic solvation. Linear relationships are observed between $(k_{obs})/[MeOH]^2$ and [AP]/[MeOH], where [AP] refers to the molar concentration of aprotic cosolvent. The results are consistent with competing third order contributions to $k_{obs}$, $k_{MM}[MeOH]^2$ with hydrogen-bonded methanol as electrophile, and $k_{MAP}[MeOH][AP]$ with hydrogen-bonding disrupted by the aprotic solvent.