• Journal of the Korean Society of Tobacco Science
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• v.30 no.1
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• pp.33-38
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• 2008

This study was carried out to determine the analytical methods for heterocyclic amines(HAs) of the tobacco smoke by LC/MS/MS. HAs have been found in pyrolysate of protein and cooked food including protein, were known the Sugimura compound. HAs content of the smoke were known to exist very low ppb level. Especially, some of HAs are mutagenic and carcinogenic compounds. In according to IARC, the toxicity of N-heterocyclic amines classified IARC class 2A or 2B group. Precursors of these compounds are glutamic acid, protein and free amino acids including tryptophan, therefore, the precursors have been proved in cooked food continuously. This study was investigate multiple analysis methods for HAs and HAs contents of some commercial products. In this study, we used the linear type smoking machine for HAs analysis. At the ISO conditions, mainstream smoke was collected on cambridge filter pad, and then cambridge filter pad was extracted by 0.1% acetic acid. The extracted solution were passed cation exchange SPE cartridge to remove matrix, samples were analyzed using LC/MS/MS on MRM mode. From the result that optimized this methods, the correlation coefficient(R) of the individual compounds were good linearity over 0.999, recovery rate over 96% and the limit of detection were good values between 0.06 to 0.37 ng/mL, In addition, HAs content of some commercial products were in range of 0.02 to 43.8 ng/cig.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3815-3817
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• 2010

• Bulletin of the Korean Chemical Society
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• v.24 no.10
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• pp.1429-1432
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• 2003

A novel fused thiouracil containing a heterocyclic ring system, dipyrimidinopyridine (3), has been prepared through the cyclization of compound 2. Compound 2 was formed by the formylation of 6-amino-2-thiouracil 1, pyrazolopyrimidines 8-10 via the heating of 6-arylhydrazono-2-thiouracils 5-7, compound 11, using Vilsmeier reagent with compound 4, pyrazolylpyrimidine 12, indolodiazinopyrimidine 14 and pyridazinopyrimidine 15. Pyridazino-pyrimidine 15 was formed by the condensation of compound 4 with acetylacetone, isatin and benzyl, respectively.

• Archives of Pharmacal Research
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• v.29 no.10
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• pp.826-833
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• 2006

Previously, we synthesized and evaluated several benzofuran derivatives containing heterocyclic ring substituents linked to the benzofuran nucleus at C-2 by a two- to four-atom spacer as potential anti-HIV-1, anticancer and antimicrobial agents. Among these derivatives, NSC 725612 and NSC 725716 exhibited interesting anti-HIV-1 activity. To further investigate the structure-activity relationship, we synthesized several new benzofuran derivatives derived from 2-acetylbenzofuran (2, 3a-c) and 2-bromoacetylbenzofuran (6; 7a,b; 8a,b). The compounds were designed to comprise the heterocyclic substituents directly linked to the benzofuran nucleus at C-2. Moreover, various related benzimidazoles derived from 2-acetylbenzimidazole and from 2-cyanomethylbenzimidazole (12a,b; 13a,b; 15; 16a,b) were also prepared as isosteres. The synthesized compounds were preliminarily evaluated for their in vitro anti-HIV-1, anticancer and antimicrobial activity. Compounds 2, 3a, 3b, and 12b showed weak anti-HIV-1 activity. Compound 6 exhibited mild activity against S. aureus, while compound 15 had mild activity towards S. aureus and C. albicans. However, no significant anticancer activity was observed with any of the tested compounds. From these results, we conclude that the presence of the spacer between the heterocyclic substituent and the benzofuran nucleus may be essential for the biological activity.

• Bulletin of the Korean Chemical Society
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• v.29 no.2
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• pp.377-380
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• 2008

Ground state structures and ring flipping transition states of eight- and seven-membered silicon containing heterocyclic compounds such as dithienodisilacyclooctatriene and oxadithienodisilacycloheptadiene derivatives, respectively have theoretically been investigated. Although the bithienylene moiety of the derivatives does not change the ground state structures, they significantly increase the ring flipping barrier by 13-17 kcal/mol in the case of the eight-membered rings (2, 3, and 4) in comparison with that of silicon containing heterocyclic compound 6, chosen as a model. The same moiety increases the flipping barrier of seven-membered ring (5) is only slightly (3.3 kcal/mol) in comparison with that of model compound 7. Hence, it has been concluded that not only the existing ring strain of eight-membered ring but also the bithienylene moiety collectively increases the ring flipping barrier so as to prevent such conformational changes explaining anomalous NMR behaviour of dithienodisilacyclooctatriene derivatives (2-4). In contrast, the effect of substituents R1 and R2 at the olefinic carbons of the eight-membered ring on the flipping barrier turned out to be mild.

• Bulletin of the Korean Chemical Society
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• v.19 no.1
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• pp.63-67
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• 1998

The synthesis and characterization of the monomeric group 13 heterocyclic thiosemicarbazone complexes $Me_2M[SC_4H_3CHNNC(S)SCH_3]$ (M=Al (2), Ga (3)) are described. Compounds 2-3 were prepared using $MMe_3$ (M=Al, Ga) in toluene with 2-thiophenecarboxaldehyde-S-methyldithiocarbazat e under anaerobic conditions. These complexes have been characterized by $^1H\;NMR,\; ^{13}C\; NMR$, elemental analyses, and single-crystal X-ray diffraction. 2 crystallizes in the monoclinic space group $P2_1/c$ with unit cell parameters a=10.2930(5) Å, b=18.564 (1) Å, c=7.3812(6) Å, V=1347.9(2) Å3, $D_{calc}=1.342\; gcm^{-3}$ for Z=4, 9281 reflections with $I_o<3{\sigma}\;(I_o),$ R1=0.0500 and wR2=0.0526. 3 crystalizes in the orthorhombic space group $P_{bca}$ with unit cell parameters a=13.340(3) Å, b=19.9070(5) Å, c=11.3690(2) Å, $V=2673.88(9)\;{\AA}^3$, $D_{calc}=1.511\; gcm^{-3}$ for Z=8, 17004 reflections with $I_o>3{\sigma}\;(I_o),$, R1=0.0480 and wR2=0.0524. Compound 3 is a monomeric gallium compound with a weak interaction between the pendant thiophene and the gallium center.

• Bulletin of the Korean Chemical Society
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• v.31 no.5
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• pp.1305-1308
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• 2010

Regioselective perfluorinated isoxazolidine (5 and 7), isoxazoline (9) and 1,2-addition products (6 and 8) having a long alkyl chain functionality have been prepared by 1,3-dipolar cycloaddition between a 1,3-dipole (NH-nitrone or nitrile oxide) and dipolarophile (perfluoro-2-methyl-2-pentene or styrene), respectively. Interestingly, unusual extended conjugated form of isoxazoline adduct (10) was obtained by dehydrofluorinated reaction from the corresponding perfluorinated isoxazoline adduct (9) which was derived from cycloadition between the perfluorinated long alkyl nitrile oxide 1,3-diplole and styrene olefin. This synthetic methodology of heterocyclic compound having a long alkyl chain functionality is useful for the designing of synthetic strategy and potential self-assembled monolayers (SAM) application. These derivatives were characterized by IR, $^1H$ and $^{19}F$ NMR, and MASS analysis.

• Preventive Nutrition and Food Science
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• v.2 no.4
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• pp.360-367
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• 1997

The chemistry background of the Maillard reaction focused on pyrazines and factors affecting the reaction products were reviewed. The Maillard reaction, also called a non-enzymatic browning reaction, is quite complex and generates numerous reaction products. In processed foods, it is generally accepted as a key reaction to produce flavor components. Specially, pyrazines possess an important impact character on the roasted foods with other heterocyclic compounds. The Maillard reaction is initiated by condensation between reducing sugar and amino group, and N-glycosylamines are produced via Schiff base with dehydration of water. After the rearrangement of the N-glycosylamines, they follow transformation into deoxyhexosones which are reactive intermediates. Degradation and fragmentation are facilitated by rearranged compounds. By condensation, pyrazine, one of the final Maillard products, is generated as a relatively stable form to provide specific aromas. During the processes of the reaction, chemical or physical environmental parameters affect the formation of the products.

• Elastomers and Composites
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• v.12 no.1
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• pp.27-32
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• 1977

The kinetics of azo-coupling reaction of N-acetyl-H-acid (1-acetamino-8-hydroxynaphthalene-3, 6-disulfonic acid) with several heterocyclic diasonium compounds such as diazotiged 3-aminopyridine, 3-aminoquinoline, 8-aminoauinoline and aniline was studied. It was found that reactions proceeded at remarkably different rate. Reaction rate was in increasing order; 3-aminopyridine, 3-aminoquinoline, 8-aminoauinoline and aniline. And the activation energies were 9.62, 10.10, 10.39, 10.70 Kcal/mole, respectively. Especially, the rate constant of 3-aminopyridine was 100 times larger than that of benzene diasonium compound even in strong acidity. Hammett plot was also made of the rate constants obtained against the heterocyclic substituent constants reported in the literature. A good linear relationship was obtained and the reaction constant of N-acetyl H-acid was calculated to be 3.14.

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.973-976
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• 2011

The addition of organic ligand (${\beta}$-diketone or heterocyclic compound) to the europium (III)-containing ionic liquid resulted in bright luminescent soft materials with the molar ratio of europium/ionic liquid (IL)/ligand being 1:3:1 that exhibit bright red light under UV lamp. The luminescent properties such as emission features and lifetime of $^5D_0$ $Eu^{3+}$ excited level are dependent on the organic ligands. The materials were characterized by FT-IR and luminescence spectroscopy. The data shows that at least parts of the ILs (carboxylic acid) are replaced with ${\beta}$-diketone ligand rather than the formation of europium complex with the molar ratio of $Eu^{3+}$:IL: ligand being 1:3:1, while no ILs could be replaced by the heterocyclic ligand such as Bpy and Phen.