• Fisheries and Aquatic Sciences
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• 제7권4호
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• pp.215-218
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• 2004

Marine sediments and bivalves were sampled at 20 stations from coastal regions of Korea, to investigate the levels and patterns of some chlorobenzene isomers. Total chlorobenzenes were in the range of 0.32-3.55 ng/g dry weight in marine sediments and 0.26-0.84 ng/g wet weight in bivalves. Hexachlorobenzene levels in marine sediments and bivalves were lower thar or comparable to those levels of reported in other countries. Isomeric patterns of some chlorobenzenes in marine sediments and bivalves were slightly different. However, the pre-dominant isomer in marine sediments and bivalves was 1,2,4-trichlorobenzene. Hexachlorobenzene contribution to total concentrations was higher in sediments than in bivalves.

• 대한화학회지
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• 제32권6호
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• pp.549-556
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• 1988

이미 합성된 N-benzylisonitrosoacetylacetone $imine^1$의 유기용매내에서의 구조변화를 측정하기 위하여 여러가지 유기용매에서의 핵자기공명스펙트럼 및 Carbon-13 핵자기공명 DEPT 스펙트럼 등의 분광학적인 자료를 이용하였다. 그 결과 이 시약은 monoxime의 일종으로 용매 중에서 syn- 형과 anti- 형의 기하이성질체가 공존하고 있으며 각각이 토우토메리 현상을 일으키고 있다.

• Archives of Pharmacal Research
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• 제28권3호
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• pp.294-296
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• 2005

Repeated chromatography of the n-hexane-soluble fraction of the MeOH extract of the rhizomes of Zingiber zerumbet led to the isolation of two isomers of 6-methoxy-2E,9E-humula-dien-8-one (1 and 2) and stigmast-4-en-3-one. The structures of 1 and 2 were determined by spectroscopic methods including 10 and 2D-NMR elucidated by analysis of spectroscopic data as well as by comparison with published values. This is the first report on the isolation of compounds 1 and 2 from the nature. Stigmast-4-en-3-one was first isolated from this plant.

• Archives of Pharmacal Research
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• 제22권5호
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• pp.507-514
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• 1999

6-(1-azidoalkyl)-DMNQ derivatives compared to 2-(1-azidoalkyl)-DMNQ isomers, exhibited higher cytotoxic activity against L1210 mouse leukemia cells and stronger inhibition of DNA topoisomerase-I (TOPO-I), suggesting involvement of steric hindrance. However, similar antitumor activity against mice bearing S-180 cell was shown by 2-an 6-(1-azidoalkyl)-DMNQ derivatives.

• Archives of Pharmacal Research
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• 제26권2호
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• pp.138-142
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• 2003

From the pulp of Euphoria longana (Longan Arillus), three cerebroside molecular species have been isolated. Six known cerebrosides, soyacerebrosides I and II, 1-Ο-$\beta$-D-glucopyranosyl-(2S,3R,4E,8E)-2-(2 -lignoceroylamino)-4,8-octadecadiene-1,3-diol (long an cerebroside I) and its 8Z isomer (Iongan cerebroside II), momor-cerebroside I, and phytolacca cerebroside, were identified as major components of these cerebroside molecular species. All the cerebrosides were shown to be a mixture of geometrical isomers (8E and 8Z) of sphingosine-type or phytosphingosine-type glucocerebrosides possessing 2-hydroxy fatty acids. The structures of these cerebrosides have been determined on the basis of chemical and spectroscopic evidence.

• Bulletin of the Korean Chemical Society
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• 제33권1호
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• pp.261-269
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• 2012

The cyclic dimers of enkephalin were isolated as minor components during the solution synthesis of the corresponding cyclic monomers. The ratio of cyclic dimer to monomer was approximately 1:4 from the percent of yields. In the receptor binding assay of two cyclic dimmers, ($Tyr_2-C[D-Glu-Phe-gPhe]_2$ 6, $Tyr_2-C[D-Asp-Phe-gPhe-rLeu]_2$ 8), both analogs exhibited the high preference for ${\delta}$ receptor compared to monocyclic counterparts. In the nociceptive activity, both showed about 5 times less potent than the cyclic monomers. The repeated synthesis of 14-membered cyclic analog, Tyr-C[D-Glu-Phe-gPhe-D-rLeu] 14, which was known as having three distinct cis-trans isomers, gave rise to apparently different conformational analog arousing only trans isomer. In the receptor binding assay, it showed tremendously high selectivity toward ${\mu}$ receptor $({\delta}/{\mu}=160)$.

• Bulletin of the Korean Chemical Society
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• 제29권3호
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• pp.604-608
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• 2008

A series of N-alkenyl pyrrolidine-2-thiones were synthesized by the reaction between pyrrolidine-2-thione and various aldehydes such as n-propanal, isopropanal, n-butanal, n-hexanal, n-octanal and phenylacetaldehyde in 32-86% yields using microwave irradiation technique. Only one structural E isomers were predominantly formed within 15 minutes in chlorobenezene?/p-toluenesulfonic acid monohydrate.

• 대한화학회지
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• 제7권2호
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• pp.106-114
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• 1963

The products from polymer pyrolysis at $450^{\circ}$ are cooled with ice, then liquid and gaseous portions are analysed by gas chromatography. Di-2-ethyl hexyl sebacate column, silicone oil column, silica gel column and tetraethyleneglycol dimethylether column, which was most effective for the separation of hydrocarbon gases, are used. Identification of isomers could be secured more effectively by gas chromatography than mass spectrometry. Elucidation of the mechanism for thermal decomposition of polymers could be done through the identification of pyrolysis products. Although more extensive work is needed, some patterns of polymer pyrolysis are discussed.

• 대한화학회지
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• 제7권3호
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• pp.197-202
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• 1963

The ${\alpha}-and\;{\beta}$-isomer of 4-nitroazoxybenzenes have been separated by liquid chromatography and their U.V. spectra were examined. The n${\to}{\pi}^{\ast}$ transition band of the compounds did not appear, likewise the cases of other compounds of the series. Transition band of the new isomer were as usual as those of other azoxy-compounds, whereas the ${\pi}{\to}{\pi}^{\ast}$ transition band of the other isomer which is reported in the literature shown peculier hypochromic shift and hypochromic effect. From the spectroscopic point of view it is very likely that the new isomer (m.p. $184-5^{\circ}C$) is ${\alpha}$-isomer and the other one (m.p. $152^{circ}C$) is ${\beta}$-isomer contrary to the literature.

• Bulletin of the Korean Chemical Society
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• 제29권5호
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• pp.1003-1006
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• 2008

Highly efficient syntheses of cylindol A (1) and the proposed structure of cylindol B (2) have been accomplished using common synthetic transformations from symmetrical starting materials 7 and 11, respectively. The latter synthesis revealed that the proposed structure of the natural cylindol B was assigned incorrectly. Isomers of 2 such as 15 and 16 were synthesized as a possible candidate of the natural cylindol B. However, their spectral data also did not match that of the natural cylindol B. Therefore, the structure of the natural cylindol B is yet to be resolved.