• 제목/요약/키워드: Pyridyl

검색결과 202건 처리시간 0.021초

[3,6-bis(6'-methyl-2'pyridyl)pyridazine]$ZnCl_2 (C_{16}H_{16}N_4\cdotZnCl_2)$의 결정 구조 (The Crystal Structure of [3,6-bis(6'-methyl-2'pyridyl)pyridazine]$ZnCl_2,(C_{16}H_{16}N_4\cdotZnCl_2)$)

  • 김문집;이재혁;이한준;성낙도
    • 한국결정학회지
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    • 제10권2호
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    • pp.119-124
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    • 1999

  • X-선 회절법을 이용하여 3,6-bis(6'-methyl-2'pyridyl)pyridazine을 리간드로 한 Zn(Ⅱ) 착물인 [3,6-bis(6'-methyl-2'pyridyl)pyridazine]ZnCl2 (C16H16N4·ZnCl2)의 결정구조를 규명하였다. 이 결정의 결정계는 Monoclinic이며 공간군은 P21/a이다. 단위포 상수는 a=15.053(7) Å, b=14.594(7) Å, c=7.628(3) Å이며, β=93.92(4)°, V=1671.9(13) Å3, T=293(2)K, Z=4, Dc=1.594 Mgm-3이다. 회절반점들의 세기는 Enraf-Nonius CAD-4 diffractometer로 얻었으며 Mo Kα선(λ=0.71073 Å)을 사용하였다. 분자구조는 직접법으로 풀었으며, Fo>4σ (Fo)인 1750개의 독립 회절 데이터에 대하여 최소승자법으로 정밀화하여 최종 신뢰도 값 R=8.31%을 얻었다.

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N,N'-Oxalylbis(2-pyridyl-3'-sulphobenzoylhydrazone)을 이용한 철의 형광광도법 정량 (Fluorimetric Determination of Iron with N,N'-Oxalylbis(2-pyridyl-3'-sulphobenzoylhydrazone))

  • 박기민;김용남
    • 대한화학회지
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    • 제37권6호
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    • pp.585-589
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    • 1993

  • N,N'-oxalylbis(2-pyridyl-3'-sulphobenzoyl hydrazone)(OPSH)를 발광시약으로 사용하여 형광광도법으로 Fe(Ⅲ)을 정량하는 방법을 개발하였다. pH 3인 수용액에서 290 nm를 들뜸 파장으로 하여 367 nm에서 Fe(Ⅲ) 착물의 형광세기를 측정하여 정량하였다. Fe(Ⅲ)의 농도가 2000~10ng/ml인 범위에서 정량이 가능하였으며 이 방법을 합성시료 및 수도물의 분석에 적용하였다.

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Aminolysis of Benzyl 2-Pyridyl Thionocarbonate and t-Butyl 2-Pyridyl Thionocarbonate: Effects of Nonleaving Groups on Reactivity and Reaction Mechanism

  • Kim, Min-Young;Lee, Jae-In;Um, Ik-Hwan
    • Bulletin of the Korean Chemical Society
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    • 제34권4호
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    • pp.1115-1119
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    • 2013

  • A kinetic study is reported for nucleophilic substitution reactions of benzyl 2-pyridyl thionocarbonate (5b) and t-butyl 2-pyridyl thionocarbonate (6b) with a series of alicyclic secondary amines in $H_2O$ at $25.0^{\circ}C$. General-base catalysis, which has often been reported to occur for aminolysis of esters possessing a C=S electrophilic center, is absent for the reactions of 5b and 6b. The Br${\o}$nsted-type plots for the reactions of 5b and 6b are linear with ${\beta}_{nuc}$ = 0.29 and 0.43, respectively, indicating that the reactions of 5b proceed through a stepwise mechanism with formation of a zwitterionic tetrahedral intermediate ($T^{\pm}$) being the rate-determining step while those of 6b proceed through a concerted mechanism. The reactivity of 5b and 6b is similar to that of their oxygen analogues (i.e., benzyl 2-pyridyl carbonate 5a and t-butyl 2-pyridyl carbonate 6a, respectively), indicating that the effect of modification of the electrophilic center from C=O to C=S (i.e., from 5a to 5b and from 6a to 6b) on reactivity is insignificant. In contrast, 6b is much less reactive than 5b, indicating that the replacement of the $PhCH_2$ in 5b by the t-Bu in 6b results in a significant decrease in reactivity as well as a change in the reaction mechanism (i.e., from a stepwise mechanism to a concerted pathway). It has been concluded that the contrasting reactivity and reaction mechanism for the reactions of 5b and 6b are not due to the electronic effects of $PhCH_2$ and t-Bu but are caused by the large steric hindrance exerted by the bulky t-Bu in 6b.

  • https://doi.org/10.5012/bkcs.2013.34.4.1115 인용 PDF KSCI

A Kinetic Study on Aminolysis of Benzyl 2-Pyridyl Thionocarbonate and t-Butyl 2-Pyridyl Thionocarbonate: Effects of Polarizability and Steric Hindrance on Reactivity and Reaction Mechanism

  • Kim, Min-Young;Bae, Ae Ri;Um, Ik-Hwan
    • Bulletin of the Korean Chemical Society
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    • 제34권8호
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    • pp.2325-2329
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    • 2013

  • Second-order rate constants $k_N$ have been measured for reactions of benzyl 2-pyridyl thionocarbonate (4b) and t-butyl 2-pyridyl thionocarbonate (5b) with a series of cyclic secondary amines in MeCN at $25.0{\pm}0.1^{\circ}C$. The $k_N$ values for the reactions of 4b and 5b have been compared with those reported previously for the corresponding reactions of benzyl 2-pyridyl carbonate (4a) and t-butyl 2-pyridyl carbonate (5a) to investigate the effect of changing the electrophilic center from C=O to C=S on reactivity and reaction mechanism. The thiono compound 4b is more reactive than its oxygen analogue 4a. The Br${\o}$nsted-type plots for the reactions of 4a and 4b are linear with ${\beta}_{nuc}=0.57$ and 0.37, respectively. The reactions of 4a were previously reported to proceed through a concerted mechanism, while those of 4b in this study have been concluded to proceed through a stepwise mechanism with formation of an intermediate being the rate-determining step on the basis of the ${\beta}_{nuc}$ value of 0.37. Enhanced polarizability upon changing the C=O in 4a by C=S has been suggested to be responsible for the reactivity order and the contrasting reaction mechanisms. In contrast, the reactivity of 5a and 5b is similar, but they are much less reactive than 4a and 4b. Furthermore, the reactions of 5a and 5b have been concluded to proceed through the same mechanism (i.e., a concerted mechanism) on the basis of linear Bronsted-type plots with ${\beta}_{nuc}=0.45$ or 0.47. It has been concluded that the strong steric hindrance exerted by the t-Bu in 5a and 5b causes a decrease in their reactivity and forces the reactions to proceed through a concerted mechanism.

  • https://doi.org/10.5012/bkcs.2013.34.8.2325 인용 PDF KSCI